lm32_cpu.v

// =============================================================================
//                           COPYRIGHT NOTICE
// Copyright 2006 (c) Lattice Semiconductor Corporation
// ALL RIGHTS RESERVED
// This confidential and proprietary software may be used only as authorised by
// a licensing agreement from Lattice Semiconductor Corporation.
// The entire notice above must be reproduced on all authorized copies and
// copies may only be made to the extent permitted by a licensing agreement from
// Lattice Semiconductor Corporation.
//
// Lattice Semiconductor Corporation        TEL : 1-800-Lattice (USA and Canada)
// 5555 NE Moore Court                            408-826-6000 (other locations)
// Hillsboro, OR 97124                     web  : http://www.latticesemi.com/
// U.S.A                                   email: techsupport@latticesemi.com
// =============================================================================/
//                         FILE DETAILS
// Project          : LatticeMico32
// File             : lm32_cpu.v
// Title            : Top-level of CPU.
// Dependencies     : lm32_include.v
//
// Version 3.4
// 1. Bug Fix: In a tight infinite loop (add, sw, bi) incoming interrupts were 
//    never serviced.
//    
// Version 3.3
// 1. Feature: Support for memory that is tightly coupled to processor core, and 
//    has a single-cycle access latency (same as caches). Instruction port has
//    access to a dedicated physically-mapped memory. Data port has access to
//    a dedicated physically-mapped memory. In order to be able to manipulate
//    values in both these memories via the debugger, these memories also
//    interface with the data port of LM32.
// 2. Feature: Extended Configuration Register
// 3. Bug Fix: Removed port names that conflict with keywords reserved in System-
//    Verilog.
//
// Version 3.2
// 1. Bug Fix: Single-stepping a load/store to invalid address causes debugger to
//    hang. At the same time CPU fails to register data bus error exception. Bug
//    is caused because (a) data bus error exception occurs after load/store has
//    passed X stage and next sequential instruction (e.g., brk) is already in X
//    stage, and (b) data bus error exception had lower priority than, say, brk
//    exception.
// 2. Bug Fix: If a brk (or scall/eret/bret) sequentially follows a load/store to
//    invalid location, CPU will fail to register data bus error exception. The
//    solution is to stall scall/eret/bret/brk instructions in D pipeline stage
//    until load/store has completed.
// 3. Feature: Enable precise identification of load/store that causes seg fault.
// 4. SYNC resets used for register file when implemented in EBRs.
//
// Version 3.1
// 1. Feature: LM32 Register File can now be mapped in to on-chip block RAM (EBR)
//    instead of distributed memory by enabling the option in LM32 GUI. 
// 2. Feature: LM32 also adds a static branch predictor to improve branch 
//    performance. All immediate-based forward-pointing branches are predicted 
//    not-taken. All immediate-based backward-pointing branches are predicted taken.
// 
// Version 7.0SP2, 3.0
// No Change
//
// Version 6.1.17
// Initial Release
// =============================================================================

`include "lm32_include.v"

/////////////////////////////////////////////////////
// Module interface
/////////////////////////////////////////////////////

module lm32_cpu (
    // ----- Inputs -------
    clk_i,
`ifdef CFG_EBR_NEGEDGE_REGISTER_FILE
    clk_n_i,
`endif    
    rst_i,
    // From external devices
`ifdef CFG_INTERRUPTS_ENABLED
    interrupt_n,
`endif
    // From user logic
`ifdef CFG_USER_ENABLED
    user_result,
    user_complete,
`endif     
`ifdef CFG_JTAG_ENABLED
    // From JTAG
    jtag_clk,
    jtag_update, 
    jtag_reg_q,
    jtag_reg_addr_q,
`endif
`ifdef CFG_IWB_ENABLED
    // Instruction Wishbone master
    I_DAT_I,
    I_ACK_I,
    I_ERR_I,
    I_RTY_I,
`endif
    // Data Wishbone master
    D_DAT_I,
    D_ACK_I,
    D_ERR_I,
    D_RTY_I,
    // ----- Outputs -------
`ifdef CFG_TRACE_ENABLED
    trace_pc,
    trace_pc_valid,
    trace_exception,
    trace_eid,
    trace_eret,
`ifdef CFG_DEBUG_ENABLED
    trace_bret,
`endif
`endif
`ifdef CFG_JTAG_ENABLED
    jtag_reg_d,
    jtag_reg_addr_d,
`endif
`ifdef CFG_USER_ENABLED    
    user_valid,
    user_opcode,
    user_operand_0,
    user_operand_1,
`endif    
`ifdef CFG_IWB_ENABLED
    // Instruction Wishbone master
    I_DAT_O,
    I_ADR_O,
    I_CYC_O,
    I_SEL_O,
    I_STB_O,
    I_WE_O,
    I_CTI_O,
    I_LOCK_O,
    I_BTE_O,
`endif
    // Data Wishbone master
    D_DAT_O,
    D_ADR_O,
    D_CYC_O,
    D_SEL_O,
    D_STB_O,
    D_WE_O,
    D_CTI_O,
    D_LOCK_O,
    D_BTE_O
    );

/////////////////////////////////////////////////////
// Parameters
/////////////////////////////////////////////////////

parameter eba_reset = `CFG_EBA_RESET;                           // Reset value for EBA CSR
`ifdef CFG_DEBUG_ENABLED
parameter deba_reset = `CFG_DEBA_RESET;                         // Reset value for DEBA CSR
`endif

`ifdef CFG_ICACHE_ENABLED
parameter icache_associativity = `CFG_ICACHE_ASSOCIATIVITY;     // Associativity of the cache (Number of ways)
parameter icache_sets = `CFG_ICACHE_SETS;                       // Number of sets
parameter icache_bytes_per_line = `CFG_ICACHE_BYTES_PER_LINE;   // Number of bytes per cache line
parameter icache_base_address = `CFG_ICACHE_BASE_ADDRESS;       // Base address of cachable memory
parameter icache_limit = `CFG_ICACHE_LIMIT;                     // Limit (highest address) of cachable memory
`else
parameter icache_associativity = 1;    
parameter icache_sets = 512;                      
parameter icache_bytes_per_line = 16;  
parameter icache_base_address = 0;      
parameter icache_limit = 0;                    
`endif

`ifdef CFG_DCACHE_ENABLED
parameter dcache_associativity = `CFG_DCACHE_ASSOCIATIVITY;     // Associativity of the cache (Number of ways)
parameter dcache_sets = `CFG_DCACHE_SETS;                       // Number of sets
parameter dcache_bytes_per_line = `CFG_DCACHE_BYTES_PER_LINE;   // Number of bytes per cache line
parameter dcache_base_address = `CFG_DCACHE_BASE_ADDRESS;       // Base address of cachable memory
parameter dcache_limit = `CFG_DCACHE_LIMIT;                     // Limit (highest address) of cachable memory
`else
parameter dcache_associativity = 1;    
parameter dcache_sets = 512;                      
parameter dcache_bytes_per_line = 16;  
parameter dcache_base_address = 0;      
parameter dcache_limit = 0;                    
`endif

`ifdef CFG_DEBUG_ENABLED
parameter watchpoints = `CFG_WATCHPOINTS;                       // Number of h/w watchpoint CSRs
`else
parameter watchpoints = 0;
`endif
`ifdef CFG_ROM_DEBUG_ENABLED
parameter breakpoints = `CFG_BREAKPOINTS;                       // Number of h/w breakpoint CSRs
`else
parameter breakpoints = 0;
`endif

`ifdef CFG_INTERRUPTS_ENABLED
parameter interrupts = `CFG_INTERRUPTS;                         // Number of interrupts
`else
parameter interrupts = 0;
`endif

/////////////////////////////////////////////////////
// Inputs
/////////////////////////////////////////////////////

input clk_i;                                    // Clock
`ifdef CFG_EBR_NEGEDGE_REGISTER_FILE
input clk_n_i;                                  // Inverted clock
`endif    
input rst_i;                                    // Reset

`ifdef CFG_INTERRUPTS_ENABLED
input [`LM32_INTERRUPT_RNG] interrupt_n;        // Interrupt pins, active-low
`endif

`ifdef CFG_USER_ENABLED
input [`LM32_WORD_RNG] user_result;             // User-defined instruction result
input user_complete;                            // User-defined instruction execution is complete
`endif    

`ifdef CFG_JTAG_ENABLED
input jtag_clk;                                 // JTAG clock
input jtag_update;                              // JTAG state machine is in data register update state
input [`LM32_BYTE_RNG] jtag_reg_q;              
input [2:0] jtag_reg_addr_q;
`endif

`ifdef CFG_IWB_ENABLED
input [`LM32_WORD_RNG] I_DAT_I;                 // Instruction Wishbone interface read data
input I_ACK_I;                                  // Instruction Wishbone interface acknowledgement
input I_ERR_I;                                  // Instruction Wishbone interface error
input I_RTY_I;                                  // Instruction Wishbone interface retry
`endif

input [`LM32_WORD_RNG] D_DAT_I;                 // Data Wishbone interface read data
input D_ACK_I;                                  // Data Wishbone interface acknowledgement
input D_ERR_I;                                  // Data Wishbone interface error
input D_RTY_I;                                  // Data Wishbone interface retry

/////////////////////////////////////////////////////
// Outputs
/////////////////////////////////////////////////////

`ifdef CFG_TRACE_ENABLED
output [`LM32_PC_RNG] trace_pc;                 // PC to trace
reg    [`LM32_PC_RNG] trace_pc;
output trace_pc_valid;                          // Indicates that a new trace PC is valid
reg    trace_pc_valid;
output trace_exception;                         // Indicates an exception has occured
reg    trace_exception;
output [`LM32_EID_RNG] trace_eid;               // Indicates what type of exception has occured
reg    [`LM32_EID_RNG] trace_eid;
output trace_eret;                              // Indicates an eret instruction has been executed
reg    trace_eret;
`ifdef CFG_DEBUG_ENABLED
output trace_bret;                              // Indicates a bret instruction has been executed
reg    trace_bret;
`endif
`endif

`ifdef CFG_JTAG_ENABLED
output [`LM32_BYTE_RNG] jtag_reg_d;
wire   [`LM32_BYTE_RNG] jtag_reg_d;
output [2:0] jtag_reg_addr_d;
wire   [2:0] jtag_reg_addr_d;
`endif

`ifdef CFG_USER_ENABLED
output user_valid;                              // Indicates if user_opcode is valid
wire   user_valid;
output [`LM32_USER_OPCODE_RNG] user_opcode;     // User-defined instruction opcode
reg    [`LM32_USER_OPCODE_RNG] user_opcode;
output [`LM32_WORD_RNG] user_operand_0;         // First operand for user-defined instruction
wire   [`LM32_WORD_RNG] user_operand_0;
output [`LM32_WORD_RNG] user_operand_1;         // Second operand for user-defined instruction
wire   [`LM32_WORD_RNG] user_operand_1;
`endif

`ifdef CFG_IWB_ENABLED
output [`LM32_WORD_RNG] I_DAT_O;                // Instruction Wishbone interface write data
wire   [`LM32_WORD_RNG] I_DAT_O;
output [`LM32_WORD_RNG] I_ADR_O;                // Instruction Wishbone interface address
wire   [`LM32_WORD_RNG] I_ADR_O;
output I_CYC_O;                                 // Instruction Wishbone interface cycle
wire   I_CYC_O;
output [`LM32_BYTE_SELECT_RNG] I_SEL_O;         // Instruction Wishbone interface byte select
wire   [`LM32_BYTE_SELECT_RNG] I_SEL_O;
output I_STB_O;                                 // Instruction Wishbone interface strobe
wire   I_STB_O;
output I_WE_O;                                  // Instruction Wishbone interface write enable
wire   I_WE_O;
output [`LM32_CTYPE_RNG] I_CTI_O;               // Instruction Wishbone interface cycle type 
wire   [`LM32_CTYPE_RNG] I_CTI_O;
output I_LOCK_O;                                // Instruction Wishbone interface lock bus
wire   I_LOCK_O;
output [`LM32_BTYPE_RNG] I_BTE_O;               // Instruction Wishbone interface burst type 
wire   [`LM32_BTYPE_RNG] I_BTE_O;
`endif

output [`LM32_WORD_RNG] D_DAT_O;                // Data Wishbone interface write data
wire   [`LM32_WORD_RNG] D_DAT_O;
output [`LM32_WORD_RNG] D_ADR_O;                // Data Wishbone interface address
wire   [`LM32_WORD_RNG] D_ADR_O;
output D_CYC_O;                                 // Data Wishbone interface cycle
wire   D_CYC_O;
output [`LM32_BYTE_SELECT_RNG] D_SEL_O;         // Data Wishbone interface byte select
wire   [`LM32_BYTE_SELECT_RNG] D_SEL_O;
output D_STB_O;                                 // Data Wishbone interface strobe
wire   D_STB_O;
output D_WE_O;                                  // Data Wishbone interface write enable
wire   D_WE_O;
output [`LM32_CTYPE_RNG] D_CTI_O;               // Data Wishbone interface cycle type 
wire   [`LM32_CTYPE_RNG] D_CTI_O;
output D_LOCK_O;                                // Date Wishbone interface lock bus
wire   D_LOCK_O;
output [`LM32_BTYPE_RNG] D_BTE_O;               // Data Wishbone interface burst type 
wire   [`LM32_BTYPE_RNG] D_BTE_O;

/////////////////////////////////////////////////////
// Internal nets and registers 
/////////////////////////////////////////////////////

// Pipeline registers

`ifdef LM32_CACHE_ENABLED
reg valid_a;                                    // Instruction in A stage is valid
`endif
reg valid_f;                                    // Instruction in F stage is valid
reg valid_d;                                    // Instruction in D stage is valid
reg valid_x;                                    // Instruction in X stage is valid
reg valid_m;                                    // Instruction in M stage is valid
reg valid_w;                                    // Instruction in W stage is valid
   
wire q_x;
wire [`LM32_WORD_RNG] immediate_d;              // Immediate operand
wire load_d;                                    // Indicates a load instruction
reg load_x;                                     
reg load_m;
wire load_q_x;
wire store_q_x;
wire store_d;                                   // Indicates a store instruction
reg store_x;
reg store_m;
wire [`LM32_SIZE_RNG] size_d;                   // Size of load/store (byte, hword, word)
reg [`LM32_SIZE_RNG] size_x;
wire branch_d;                                  // Indicates a branch instruction
wire branch_predict_d;                          // Indicates a branch is predicted
wire branch_predict_taken_d;                    // Indicates a branch is predicted taken
wire [`LM32_PC_RNG] branch_predict_address_d;   // Address to which predicted branch jumps
wire [`LM32_PC_RNG] branch_target_d;
wire bi_unconditional;
wire bi_conditional;
reg branch_x;                                   
reg branch_predict_x;
reg branch_predict_taken_x;
reg branch_m;
reg branch_predict_m;
reg branch_predict_taken_m;
wire branch_mispredict_taken_m;                 // Indicates a branch was mispredicted as taken
wire branch_flushX_m;                           // Indicates that instruction in X stage must be squashed
wire branch_reg_d;                              // Branch to register or immediate
wire [`LM32_PC_RNG] branch_offset_d;            // Branch offset for immediate branches
reg [`LM32_PC_RNG] branch_target_x;             // Address to branch to
reg [`LM32_PC_RNG] branch_target_m;
wire [`LM32_D_RESULT_SEL_0_RNG] d_result_sel_0_d; // Which result should be selected in D stage for operand 0
wire [`LM32_D_RESULT_SEL_1_RNG] d_result_sel_1_d; // Which result should be selected in D stage for operand 1

wire x_result_sel_csr_d;                        // Select X stage result from CSRs
reg x_result_sel_csr_x;
`ifdef LM32_MC_ARITHMETIC_ENABLED
wire x_result_sel_mc_arith_d;                   // Select X stage result from multi-cycle arithmetic unit
reg x_result_sel_mc_arith_x;
`endif
`ifdef LM32_NO_BARREL_SHIFT    
wire x_result_sel_shift_d;                      // Select X stage result from shifter
reg x_result_sel_shift_x;
`endif
`ifdef CFG_SIGN_EXTEND_ENABLED
wire x_result_sel_sext_d;                       // Select X stage result from sign-extend logic
reg x_result_sel_sext_x;
`endif
wire x_result_sel_logic_d;                      // Select X stage result from logic op unit
reg x_result_sel_logic_x;
`ifdef CFG_USER_ENABLED
wire x_result_sel_user_d;                       // Select X stage result from user-defined logic
reg x_result_sel_user_x;
`endif
wire x_result_sel_add_d;                        // Select X stage result from adder
reg x_result_sel_add_x;
wire m_result_sel_compare_d;                    // Select M stage result from comparison logic
reg m_result_sel_compare_x;
reg m_result_sel_compare_m;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
wire m_result_sel_shift_d;                      // Select M stage result from shifter
reg m_result_sel_shift_x;
reg m_result_sel_shift_m;
`endif
wire w_result_sel_load_d;                       // Select W stage result from load/store unit
reg w_result_sel_load_x;
reg w_result_sel_load_m;
reg w_result_sel_load_w;
`ifdef CFG_PL_MULTIPLY_ENABLED
wire w_result_sel_mul_d;                        // Select W stage result from multiplier
reg w_result_sel_mul_x;
reg w_result_sel_mul_m;
reg w_result_sel_mul_w;
`endif
wire x_bypass_enable_d;                         // Whether result is bypassable in X stage
reg x_bypass_enable_x;                          
wire m_bypass_enable_d;                         // Whether result is bypassable in M stage
reg m_bypass_enable_x;                          
reg m_bypass_enable_m;
wire sign_extend_d;                             // Whether to sign-extend or zero-extend
reg sign_extend_x;
wire write_enable_d;                            // Register file write enable
reg write_enable_x;
wire write_enable_q_x;
reg write_enable_m;
wire write_enable_q_m;
reg write_enable_w;
wire write_enable_q_w;
wire read_enable_0_d;                           // Register file read enable 0
wire [`LM32_REG_IDX_RNG] read_idx_0_d;          // Register file read index 0
wire read_enable_1_d;                           // Register file read enable 1
wire [`LM32_REG_IDX_RNG] read_idx_1_d;          // Register file read index 1
wire [`LM32_REG_IDX_RNG] write_idx_d;           // Register file write index
reg [`LM32_REG_IDX_RNG] write_idx_x;            
reg [`LM32_REG_IDX_RNG] write_idx_m;
reg [`LM32_REG_IDX_RNG] write_idx_w;
wire [`LM32_CSR_RNG] csr_d;                     // CSR read/write index
reg  [`LM32_CSR_RNG] csr_x;                  
wire [`LM32_CONDITION_RNG] condition_d;         // Branch condition
reg [`LM32_CONDITION_RNG] condition_x;          
`ifdef CFG_DEBUG_ENABLED
wire break_d;                                   // Indicates a break instruction
reg break_x;                                    
`endif
wire scall_d;                                   // Indicates a scall instruction
reg scall_x;    
wire eret_d;                                    // Indicates an eret instruction
reg eret_x;
wire eret_q_x;
reg eret_m;
`ifdef CFG_TRACE_ENABLED
reg eret_w;
`endif
`ifdef CFG_DEBUG_ENABLED
wire bret_d;                                    // Indicates a bret instruction
reg bret_x;
wire bret_q_x;
reg bret_m;
`ifdef CFG_TRACE_ENABLED
reg bret_w;
`endif
`endif
wire csr_write_enable_d;                        // CSR write enable
reg csr_write_enable_x;
wire csr_write_enable_q_x;
`ifdef CFG_USER_ENABLED
wire [`LM32_USER_OPCODE_RNG] user_opcode_d;     // User-defined instruction opcode
`endif

`ifdef CFG_BUS_ERRORS_ENABLED
wire bus_error_d;                               // Indicates an bus error occured while fetching the instruction in this pipeline stage
reg bus_error_x;
reg data_bus_error_exception_m;
reg [`LM32_PC_RNG] memop_pc_w;
`endif

reg [`LM32_WORD_RNG] d_result_0;                // Result of instruction in D stage (operand 0)
reg [`LM32_WORD_RNG] d_result_1;                // Result of instruction in D stage (operand 1)
reg [`LM32_WORD_RNG] x_result;                  // Result of instruction in X stage
reg [`LM32_WORD_RNG] m_result;                  // Result of instruction in M stage
reg [`LM32_WORD_RNG] w_result;                  // Result of instruction in W stage

reg [`LM32_WORD_RNG] operand_0_x;               // Operand 0 for X stage instruction
reg [`LM32_WORD_RNG] operand_1_x;               // Operand 1 for X stage instruction
reg [`LM32_WORD_RNG] store_operand_x;           // Data read from register to store
reg [`LM32_WORD_RNG] operand_m;                 // Operand for M stage instruction
reg [`LM32_WORD_RNG] operand_w;                 // Operand for W stage instruction

// To/from register file
`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
reg [`LM32_WORD_RNG] reg_data_live_0;          
reg [`LM32_WORD_RNG] reg_data_live_1;  
reg use_buf;                                    // Whether to use reg_data_live or reg_data_buf
reg [`LM32_WORD_RNG] reg_data_buf_0;
reg [`LM32_WORD_RNG] reg_data_buf_1;
`endif
`ifdef LM32_EBR_REGISTER_FILE
`else
reg [`LM32_WORD_RNG] registers[0:(1<<`LM32_REG_IDX_WIDTH)-1];   // Register file
`endif
wire [`LM32_WORD_RNG] reg_data_0;               // Register file read port 0 data         
wire [`LM32_WORD_RNG] reg_data_1;               // Register file read port 1 data
reg [`LM32_WORD_RNG] bypass_data_0;             // Register value 0 after bypassing
reg [`LM32_WORD_RNG] bypass_data_1;             // Register value 1 after bypassing
wire reg_write_enable_q_w;

reg interlock;                                  // Indicates pipeline should be stalled because of a read-after-write hazzard

wire stall_a;                                   // Stall instruction in A pipeline stage
wire stall_f;                                   // Stall instruction in F pipeline stage
wire stall_d;                                   // Stall instruction in D pipeline stage
wire stall_x;                                   // Stall instruction in X pipeline stage
wire stall_m;                                   // Stall instruction in M pipeline stage

// To/from adder
wire adder_op_d;                                // Whether to add or subtract
reg adder_op_x;                                 
reg adder_op_x_n;                               // Inverted version of adder_op_x
wire [`LM32_WORD_RNG] adder_result_x;           // Result from adder
wire adder_overflow_x;                          // Whether a signed overflow occured
wire adder_carry_n_x;                           // Whether a carry was generated

// To/from logical operations unit
wire [`LM32_LOGIC_OP_RNG] logic_op_d;           // Which operation to perform
reg [`LM32_LOGIC_OP_RNG] logic_op_x;            
wire [`LM32_WORD_RNG] logic_result_x;           // Result of logical operation

`ifdef CFG_SIGN_EXTEND_ENABLED
// From sign-extension unit
wire [`LM32_WORD_RNG] sextb_result_x;           // Result of byte sign-extension
wire [`LM32_WORD_RNG] sexth_result_x;           // Result of half-word sign-extenstion
wire [`LM32_WORD_RNG] sext_result_x;            // Result of sign-extension specified by instruction
`endif

// To/from shifter
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
`ifdef CFG_ROTATE_ENABLED
wire rotate_d;                                  // Whether we should rotate or shift
reg rotate_x;                                    
`endif
wire direction_d;                               // Which direction to shift in
reg direction_x;                                        
reg direction_m;
wire [`LM32_WORD_RNG] shifter_result_m;         // Result of shifter
`endif
`ifdef CFG_MC_BARREL_SHIFT_ENABLED
wire shift_left_d;                              // Indicates whether to perform a left shift or not
wire shift_left_q_d;
wire shift_right_d;                             // Indicates whether to perform a right shift or not
wire shift_right_q_d;
`endif
`ifdef LM32_NO_BARREL_SHIFT
wire [`LM32_WORD_RNG] shifter_result_x;         // Result of single-bit right shifter
`endif

// To/from multiplier
`ifdef LM32_MULTIPLY_ENABLED
wire [`LM32_WORD_RNG] multiplier_result_w;      // Result from multiplier
`endif
`ifdef CFG_MC_MULTIPLY_ENABLED
wire multiply_d;                                // Indicates whether to perform a multiply or not
wire multiply_q_d;
`endif

// To/from divider
`ifdef CFG_MC_DIVIDE_ENABLED
wire divide_d;                                  // Indicates whether to perform a divider or not
wire divide_q_d;
wire modulus_d;
wire modulus_q_d;
wire divide_by_zero_x;                          // Indicates an attempt was made to divide by zero
`endif

// To from multi-cycle arithmetic unit
`ifdef LM32_MC_ARITHMETIC_ENABLED
wire mc_stall_request_x;                        // Multi-cycle arithmetic unit stall request
wire [`LM32_WORD_RNG] mc_result_x;
`endif

// From CSRs
`ifdef CFG_INTERRUPTS_ENABLED
wire [`LM32_WORD_RNG] interrupt_csr_read_data_x;// Data read from interrupt CSRs
`endif
wire [`LM32_WORD_RNG] cfg;                      // Configuration CSR
wire [`LM32_WORD_RNG] cfg2;                     // Extended Configuration CSR
`ifdef CFG_CYCLE_COUNTER_ENABLED
reg [`LM32_WORD_RNG] cc;                        // Cycle counter CSR
`endif
reg [`LM32_WORD_RNG] csr_read_data_x;           // Data read from CSRs

// To/from instruction unit
wire [`LM32_PC_RNG] pc_f;                       // PC of instruction in F stage
wire [`LM32_PC_RNG] pc_d;                       // PC of instruction in D stage
wire [`LM32_PC_RNG] pc_x;                       // PC of instruction in X stage
wire [`LM32_PC_RNG] pc_m;                       // PC of instruction in M stage
wire [`LM32_PC_RNG] pc_w;                       // PC of instruction in W stage
`ifdef CFG_TRACE_ENABLED
reg [`LM32_PC_RNG] pc_c;                        // PC of last commited instruction
`endif
`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
wire [`LM32_INSTRUCTION_RNG] instruction_f;     // Instruction in F stage
`endif
//pragma attribute instruction_d preserve_signal true
//pragma attribute instruction_d preserve_driver true
wire [`LM32_INSTRUCTION_RNG] instruction_d;     // Instruction in D stage
`ifdef CFG_ICACHE_ENABLED
wire iflush;                                    // Flush instruction cache
wire icache_stall_request;                      // Stall pipeline because instruction cache is busy
wire icache_restart_request;                    // Restart instruction that caused an instruction cache miss
wire icache_refill_request;                     // Request to refill instruction cache
wire icache_refilling;                          // Indicates the instruction cache is being refilled
`endif
`ifdef CFG_IROM_ENABLED
wire [`LM32_WORD_RNG] irom_store_data_m;        // Store data to instruction ROM
wire [`LM32_WORD_RNG] irom_address_xm;          // Address to instruction ROM from load-store unit
wire [`LM32_WORD_RNG] irom_data_m;              // Load data from instruction ROM
wire irom_we_xm;                                // Indicates data needs to be written to instruction ROM
wire irom_stall_request_x;                      // Indicates D stage needs to be stalled on a store to instruction ROM
`endif

// To/from load/store unit
`ifdef CFG_DCACHE_ENABLED
wire dflush_x;                                  // Flush data cache    
reg dflush_m;                                    
wire dcache_stall_request;                      // Stall pipeline because data cache is busy
wire dcache_restart_request;                    // Restart instruction that caused a data cache miss
wire dcache_refill_request;                     // Request to refill data cache
wire dcache_refilling;                          // Indicates the data cache is being refilled
`endif
wire [`LM32_WORD_RNG] load_data_w;              // Result of a load instruction
wire stall_wb_load;                             // Stall pipeline because of a load via the data Wishbone interface

// To/from JTAG interface
`ifdef CFG_JTAG_ENABLED
`ifdef CFG_JTAG_UART_ENABLED
wire [`LM32_WORD_RNG] jtx_csr_read_data;        // Read data for JTX CSR
wire [`LM32_WORD_RNG] jrx_csr_read_data;        // Read data for JRX CSR
`endif
`ifdef CFG_HW_DEBUG_ENABLED
wire jtag_csr_write_enable;                     // Debugger CSR write enable
wire [`LM32_WORD_RNG] jtag_csr_write_data;      // Data to write to specified CSR
wire [`LM32_CSR_RNG] jtag_csr;                  // Which CSR to write
wire jtag_read_enable;                          
wire [`LM32_BYTE_RNG] jtag_read_data;
wire jtag_write_enable;
wire [`LM32_BYTE_RNG] jtag_write_data;
wire [`LM32_WORD_RNG] jtag_address;
wire jtag_access_complete;
`endif
`ifdef CFG_DEBUG_ENABLED
wire jtag_break;                                // Request from debugger to raise a breakpoint
`endif
`endif

// Hazzard detection
wire raw_x_0;                                   // RAW hazzard between instruction in X stage and read port 0
wire raw_x_1;                                   // RAW hazzard between instruction in X stage and read port 1
wire raw_m_0;                                   // RAW hazzard between instruction in M stage and read port 0
wire raw_m_1;                                   // RAW hazzard between instruction in M stage and read port 1
wire raw_w_0;                                   // RAW hazzard between instruction in W stage and read port 0
wire raw_w_1;                                   // RAW hazzard between instruction in W stage and read port 1

// Control flow
wire cmp_zero;                                  // Result of comparison is zero
wire cmp_negative;                              // Result of comparison is negative
wire cmp_overflow;                              // Comparison produced an overflow
wire cmp_carry_n;                               // Comparison produced a carry, inverted
reg condition_met_x;                            // Condition of branch instruction is met
reg condition_met_m;
`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
wire branch_taken_x;                            // Branch is taken in X stage
`endif
wire branch_taken_m;                            // Branch is taken in M stage

wire kill_f;                                    // Kill instruction in F stage
wire kill_d;                                    // Kill instruction in D stage
wire kill_x;                                    // Kill instruction in X stage
wire kill_m;                                    // Kill instruction in M stage
wire kill_w;                                    // Kill instruction in W stage

reg [`LM32_PC_WIDTH+2-1:8] eba;                 // Exception Base Address (EBA) CSR
`ifdef CFG_DEBUG_ENABLED
reg [`LM32_PC_WIDTH+2-1:8] deba;                // Debug Exception Base Address (DEBA) CSR
`endif
reg [`LM32_EID_RNG] eid_x;                      // Exception ID in X stage
`ifdef CFG_TRACE_ENABLED
reg [`LM32_EID_RNG] eid_m;                      // Exception ID in M stage
reg [`LM32_EID_RNG] eid_w;                      // Exception ID in W stage
`endif

`ifdef CFG_DEBUG_ENABLED
`ifdef LM32_SINGLE_STEP_ENABLED
wire dc_ss;                                     // Is single-step enabled
`endif
wire dc_re;                                     // Remap all exceptions
wire exception_x;                               // An exception occured in the X stage
reg exception_m;                                // An instruction that caused an exception is in the M stage
wire debug_exception_x;                         // Indicates if a debug exception has occured
reg debug_exception_m;
reg debug_exception_w;
wire debug_exception_q_w;
wire non_debug_exception_x;                     // Indicates if a non debug exception has occured
reg non_debug_exception_m;
reg non_debug_exception_w;
wire non_debug_exception_q_w;
`else
wire exception_x;                               // Indicates if a debug exception has occured
reg exception_m;
reg exception_w;
wire exception_q_w;
`endif

`ifdef CFG_DEBUG_ENABLED
`ifdef CFG_JTAG_ENABLED
wire reset_exception;                           // Indicates if a reset exception has occured
`endif
`endif
`ifdef CFG_INTERRUPTS_ENABLED
wire interrupt_exception;                       // Indicates if an interrupt exception has occured
`endif
`ifdef CFG_DEBUG_ENABLED
wire breakpoint_exception;                      // Indicates if a breakpoint exception has occured
wire watchpoint_exception;                      // Indicates if a watchpoint exception has occured
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
wire instruction_bus_error_exception;           // Indicates if an instruction bus error exception has occured
wire data_bus_error_exception;                  // Indicates if a data bus error exception has occured
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
wire divide_by_zero_exception;                  // Indicates if a divide by zero exception has occured
`endif
wire system_call_exception;                     // Indicates if a system call exception has occured

`ifdef CFG_BUS_ERRORS_ENABLED
reg data_bus_error_seen;                        // Indicates if a data bus error was seen
`endif

/////////////////////////////////////////////////////
// Functions
/////////////////////////////////////////////////////

`include "lm32_functions.v"

/////////////////////////////////////////////////////
// Instantiations
///////////////////////////////////////////////////// 

// Instruction unit
lm32_instruction_unit #(
    .associativity          (icache_associativity),
    .sets                   (icache_sets),
    .bytes_per_line         (icache_bytes_per_line),
    .base_address           (icache_base_address),
    .limit                  (icache_limit)
  ) instruction_unit (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    // From pipeline
    .stall_a                (stall_a),
    .stall_f                (stall_f),
    .stall_d                (stall_d),
    .stall_x                (stall_x),
    .stall_m                (stall_m),
    .valid_f                (valid_f),
    .valid_d                (valid_d),
    .kill_f                 (kill_f),
    .branch_predict_taken_d (branch_predict_taken_d),
    .branch_predict_address_d (branch_predict_address_d),
`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
    .branch_taken_x         (branch_taken_x),
    .branch_target_x        (branch_target_x),
`endif
    .exception_m            (exception_m),
    .branch_taken_m         (branch_taken_m),
    .branch_mispredict_taken_m (branch_mispredict_taken_m),
    .branch_target_m        (branch_target_m),
`ifdef CFG_ICACHE_ENABLED
    .iflush                 (iflush),
`endif
`ifdef CFG_IROM_ENABLED
    .irom_store_data_m      (irom_store_data_m),
    .irom_address_xm        (irom_address_xm),
    .irom_we_xm             (irom_we_xm),
`endif
`ifdef CFG_DCACHE_ENABLED
    .dcache_restart_request (dcache_restart_request),
    .dcache_refill_request  (dcache_refill_request),
    .dcache_refilling       (dcache_refilling),
`endif        
`ifdef CFG_IWB_ENABLED
    // From Wishbone
    .i_dat_i                (I_DAT_I),
    .i_ack_i                (I_ACK_I),
    .i_err_i                (I_ERR_I),
    .i_rty_i                (I_RTY_I),
`endif
`ifdef CFG_HW_DEBUG_ENABLED
    .jtag_read_enable       (jtag_read_enable),
    .jtag_write_enable      (jtag_write_enable),
    .jtag_write_data        (jtag_write_data),
    .jtag_address           (jtag_address),
`endif
    // ----- Outputs -------
    // To pipeline
    .pc_f                   (pc_f),
    .pc_d                   (pc_d),
    .pc_x                   (pc_x),
    .pc_m                   (pc_m),
    .pc_w                   (pc_w),
`ifdef CFG_ICACHE_ENABLED
    .icache_stall_request   (icache_stall_request),
    .icache_restart_request (icache_restart_request),
    .icache_refill_request  (icache_refill_request),
    .icache_refilling       (icache_refilling),
`endif
`ifdef CFG_IROM_ENABLED
    .irom_data_m            (irom_data_m),
`endif
`ifdef CFG_IWB_ENABLED
    // To Wishbone
    .i_dat_o                (I_DAT_O),
    .i_adr_o                (I_ADR_O),
    .i_cyc_o                (I_CYC_O),
    .i_sel_o                (I_SEL_O),
    .i_stb_o                (I_STB_O),
    .i_we_o                 (I_WE_O),
    .i_cti_o                (I_CTI_O),
    .i_lock_o               (I_LOCK_O),
    .i_bte_o                (I_BTE_O),
`endif
`ifdef CFG_HW_DEBUG_ENABLED
    .jtag_read_data         (jtag_read_data),
    .jtag_access_complete   (jtag_access_complete),
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
    .bus_error_d            (bus_error_d),
`endif
`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
    .instruction_f          (instruction_f),
`endif
    .instruction_d          (instruction_d)
    );

// Instruction decoder
lm32_decoder decoder (
    // ----- Inputs -------
    .instruction            (instruction_d),
    // ----- Outputs -------
    .d_result_sel_0         (d_result_sel_0_d),
    .d_result_sel_1         (d_result_sel_1_d),
    .x_result_sel_csr       (x_result_sel_csr_d),
`ifdef LM32_MC_ARITHMETIC_ENABLED
    .x_result_sel_mc_arith  (x_result_sel_mc_arith_d),
`endif
`ifdef LM32_NO_BARREL_SHIFT    
    .x_result_sel_shift     (x_result_sel_shift_d),
`endif
`ifdef CFG_SIGN_EXTEND_ENABLED
    .x_result_sel_sext      (x_result_sel_sext_d),
`endif    
    .x_result_sel_logic     (x_result_sel_logic_d),
`ifdef CFG_USER_ENABLED
    .x_result_sel_user      (x_result_sel_user_d),
`endif
    .x_result_sel_add       (x_result_sel_add_d),
    .m_result_sel_compare   (m_result_sel_compare_d),
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
    .m_result_sel_shift     (m_result_sel_shift_d),  
`endif    
    .w_result_sel_load      (w_result_sel_load_d),
`ifdef CFG_PL_MULTIPLY_ENABLED
    .w_result_sel_mul       (w_result_sel_mul_d),
`endif
    .x_bypass_enable        (x_bypass_enable_d),
    .m_bypass_enable        (m_bypass_enable_d),
    .read_enable_0          (read_enable_0_d),
    .read_idx_0             (read_idx_0_d),
    .read_enable_1          (read_enable_1_d),
    .read_idx_1             (read_idx_1_d),
    .write_enable           (write_enable_d),
    .write_idx              (write_idx_d),
    .immediate              (immediate_d),
    .branch_offset          (branch_offset_d),
    .load                   (load_d),
    .store                  (store_d),
    .size                   (size_d),
    .sign_extend            (sign_extend_d),
    .adder_op               (adder_op_d),
    .logic_op               (logic_op_d),
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
    .direction              (direction_d),
`endif
`ifdef CFG_MC_BARREL_SHIFT_ENABLED
    .shift_left             (shift_left_d),
    .shift_right            (shift_right_d),
`endif
`ifdef CFG_MC_MULTIPLY_ENABLED
    .multiply               (multiply_d),
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
    .divide                 (divide_d),
    .modulus                (modulus_d),
`endif
    .branch                 (branch_d),
    .bi_unconditional       (bi_unconditional),
    .bi_conditional         (bi_conditional),
    .branch_reg             (branch_reg_d),
    .condition              (condition_d),
`ifdef CFG_DEBUG_ENABLED
    .break_opcode           (break_d),
`endif
    .scall                  (scall_d),
    .eret                   (eret_d),
`ifdef CFG_DEBUG_ENABLED
    .bret                   (bret_d),
`endif
`ifdef CFG_USER_ENABLED
    .user_opcode            (user_opcode_d),
`endif
    .csr_write_enable       (csr_write_enable_d)
    ); 

// Load/store unit       
lm32_load_store_unit #(
    .associativity          (dcache_associativity),
    .sets                   (dcache_sets),
    .bytes_per_line         (dcache_bytes_per_line),
    .base_address           (dcache_base_address),
    .limit                  (dcache_limit)
  ) load_store_unit (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    // From pipeline
    .stall_a                (stall_a),
    .stall_x                (stall_x),
    .stall_m                (stall_m),
    .kill_x                 (kill_x),
    .kill_m                 (kill_m),
    .exception_m            (exception_m),
    .store_operand_x        (store_operand_x),
    .load_store_address_x   (adder_result_x),
    .load_store_address_m   (operand_m),
    .load_store_address_w   (operand_w[1:0]),
    .load_x                 (load_x),
    .store_x                (store_x),
    .load_q_x               (load_q_x),
    .store_q_x              (store_q_x),
    .load_q_m               (load_q_m),
    .store_q_m              (store_q_m),
    .sign_extend_x          (sign_extend_x),
    .size_x                 (size_x),
`ifdef CFG_DCACHE_ENABLED
    .dflush                 (dflush_m),
`endif
`ifdef CFG_IROM_ENABLED
    .irom_data_m            (irom_data_m),
`endif
    // From Wishbone
    .d_dat_i                (D_DAT_I),
    .d_ack_i                (D_ACK_I),
    .d_err_i                (D_ERR_I),
    .d_rty_i                (D_RTY_I),
    // ----- Outputs -------
    // To pipeline
`ifdef CFG_DCACHE_ENABLED
    .dcache_refill_request  (dcache_refill_request),
    .dcache_restart_request (dcache_restart_request),
    .dcache_stall_request   (dcache_stall_request),
    .dcache_refilling       (dcache_refilling),
`endif    
`ifdef CFG_IROM_ENABLED
    .irom_store_data_m      (irom_store_data_m),
    .irom_address_xm        (irom_address_xm),
    .irom_we_xm             (irom_we_xm),
    .irom_stall_request_x   (irom_stall_request_x),
`endif
    .load_data_w            (load_data_w),
    .stall_wb_load          (stall_wb_load),
    // To Wishbone
    .d_dat_o                (D_DAT_O),
    .d_adr_o                (D_ADR_O),
    .d_cyc_o                (D_CYC_O),
    .d_sel_o                (D_SEL_O),
    .d_stb_o                (D_STB_O),
    .d_we_o                 (D_WE_O),
    .d_cti_o                (D_CTI_O),
    .d_lock_o               (D_LOCK_O),
    .d_bte_o                (D_BTE_O)
    );      
       
// Adder       
lm32_adder adder (
    // ----- Inputs -------
    .adder_op_x             (adder_op_x),
    .adder_op_x_n           (adder_op_x_n),
    .operand_0_x            (operand_0_x),
    .operand_1_x            (operand_1_x),
    // ----- Outputs -------
    .adder_result_x         (adder_result_x),
    .adder_carry_n_x        (adder_carry_n_x),
    .adder_overflow_x       (adder_overflow_x)
    );

// Logic operations
lm32_logic_op logic_op (
    // ----- Inputs -------
    .logic_op_x             (logic_op_x),
    .operand_0_x            (operand_0_x),

    .operand_1_x            (operand_1_x),
    // ----- Outputs -------
    .logic_result_x         (logic_result_x)
    );
              
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
// Pipelined barrel-shifter
lm32_shifter shifter (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    .stall_x                (stall_x),
    .direction_x            (direction_x),
    .sign_extend_x          (sign_extend_x),
    .operand_0_x            (operand_0_x),
    .operand_1_x            (operand_1_x),
    // ----- Outputs -------
    .shifter_result_m       (shifter_result_m)
    );
`endif

`ifdef CFG_PL_MULTIPLY_ENABLED
// Pipeline fixed-point multiplier
lm32_multiplier multiplier (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    .stall_x                (stall_x),
    .stall_m                (stall_m),
    .operand_0              (d_result_0),
    .operand_1              (d_result_1),
    // ----- Outputs -------
    .result                 (multiplier_result_w)    
    );
`endif

`ifdef LM32_MC_ARITHMETIC_ENABLED
// Multi-cycle arithmetic
lm32_mc_arithmetic mc_arithmetic (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    .stall_d                (stall_d),
    .kill_x                 (kill_x),
`ifdef CFG_MC_DIVIDE_ENABLED                  
    .divide_d               (divide_q_d),
    .modulus_d              (modulus_q_d),
`endif
`ifdef CFG_MC_MULTIPLY_ENABLED        
    .multiply_d             (multiply_q_d),
`endif
`ifdef CFG_MC_BARREL_SHIFT_ENABLED
    .shift_left_d           (shift_left_q_d),
    .shift_right_d          (shift_right_q_d),
    .sign_extend_d          (sign_extend_d),
`endif    
    .operand_0_d            (d_result_0),
    .operand_1_d            (d_result_1),
    // ----- Outputs -------
    .result_x               (mc_result_x),
`ifdef CFG_MC_DIVIDE_ENABLED                  
    .divide_by_zero_x       (divide_by_zero_x),
`endif
    .stall_request_x        (mc_stall_request_x)
    );
`endif
              
`ifdef CFG_INTERRUPTS_ENABLED
// Interrupt unit
lm32_interrupt interrupt (
    // ----- Inputs -------
    .clk_i                  (clk_i), 
    .rst_i                  (rst_i),
    // From external devices
    .interrupt_n            (interrupt_n),
    // From pipeline
    .stall_x                (stall_x),
`ifdef CFG_DEBUG_ENABLED
    .non_debug_exception    (non_debug_exception_q_w), 
    .debug_exception        (debug_exception_q_w),
`else
    .exception              (exception_q_w), 
`endif
    .eret_q_x               (eret_q_x),
`ifdef CFG_DEBUG_ENABLED
    .bret_q_x               (bret_q_x),
`endif
    .csr                    (csr_x),
    .csr_write_data         (operand_1_x),
    .csr_write_enable       (csr_write_enable_q_x),
    // ----- Outputs -------
    .interrupt_exception    (interrupt_exception),
    // To pipeline
    .csr_read_data          (interrupt_csr_read_data_x)
    );
`endif

`ifdef CFG_JTAG_ENABLED
// JTAG interface
lm32_jtag jtag (
    // ----- Inputs -------
    .clk_i                  (clk_i),
    .rst_i                  (rst_i),
    // From JTAG
    .jtag_clk               (jtag_clk),
    .jtag_update            (jtag_update),
    .jtag_reg_q             (jtag_reg_q),
    .jtag_reg_addr_q        (jtag_reg_addr_q),
    // From pipeline
`ifdef CFG_JTAG_UART_ENABLED
    .csr                    (csr_x),
    .csr_write_data         (operand_1_x),
    .csr_write_enable       (csr_write_enable_q_x),
    .stall_x                (stall_x),
`endif
`ifdef CFG_HW_DEBUG_ENABLED
    .jtag_read_data         (jtag_read_data),
    .jtag_access_complete   (jtag_access_complete),
`endif
`ifdef CFG_DEBUG_ENABLED
    .exception_q_w          (debug_exception_q_w || non_debug_exception_q_w),
`endif    
    // ----- Outputs -------
    // To pipeline
`ifdef CFG_JTAG_UART_ENABLED
    .jtx_csr_read_data      (jtx_csr_read_data),
    .jrx_csr_read_data      (jrx_csr_read_data),
`endif
`ifdef CFG_HW_DEBUG_ENABLED
    .jtag_csr_write_enable  (jtag_csr_write_enable),
    .jtag_csr_write_data    (jtag_csr_write_data),
    .jtag_csr               (jtag_csr),
    .jtag_read_enable       (jtag_read_enable),
    .jtag_write_enable      (jtag_write_enable),
    .jtag_write_data        (jtag_write_data),
    .jtag_address           (jtag_address),
`endif
`ifdef CFG_DEBUG_ENABLED
    .jtag_break             (jtag_break),
    .jtag_reset             (reset_exception),
`endif
    // To JTAG 
    .jtag_reg_d             (jtag_reg_d),
    .jtag_reg_addr_d        (jtag_reg_addr_d)
    );
`endif

`ifdef CFG_DEBUG_ENABLED
// Debug unit
lm32_debug #(
    .breakpoints            (breakpoints),
    .watchpoints            (watchpoints)
  ) hw_debug (
    // ----- Inputs -------
    .clk_i                  (clk_i), 
    .rst_i                  (rst_i),
    .pc_x                   (pc_x),
    .load_x                 (load_x),
    .store_x                (store_x),
    .load_store_address_x   (adder_result_x),
    .csr_write_enable_x     (csr_write_enable_q_x),
    .csr_write_data         (operand_1_x),
    .csr_x                  (csr_x),
`ifdef CFG_HW_DEBUG_ENABLED
    .jtag_csr_write_enable  (jtag_csr_write_enable),
    .jtag_csr_write_data    (jtag_csr_write_data),
    .jtag_csr               (jtag_csr),
`endif
`ifdef LM32_SINGLE_STEP_ENABLED
    .eret_q_x               (eret_q_x),
    .bret_q_x               (bret_q_x),
    .stall_x                (stall_x),
    .exception_x            (exception_x),
    .q_x                    (q_x),
`ifdef CFG_DCACHE_ENABLED
    .dcache_refill_request  (dcache_refill_request),
`endif
`endif
    // ----- Outputs -------
`ifdef LM32_SINGLE_STEP_ENABLED
    .dc_ss                  (dc_ss),
`endif
    .dc_re                  (dc_re),
    .bp_match               (bp_match),
    .wp_match               (wp_match)
    );
`endif

// Register file

`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
   /*----------------------------------------------------------------------
    Register File is implemented using EBRs. There can be three accesses to
    the register file in each cycle: two reads and one write. On-chip block
    RAM has two read/write ports. To accomodate three accesses, two on-chip
    block RAMs are used (each register file "write" is made to both block
    RAMs).
    
    One limitation of the on-chip block RAMs is that one cannot perform a 
    read and write to same location in a cycle (if this is done, then the
    data read out is indeterminate).
    ----------------------------------------------------------------------*/
   wire [31:0] regfile_data_0, regfile_data_1;
   reg [31:0]  w_result_d;
   reg 	       regfile_raw_0, regfile_raw_0_nxt;
   reg 	       regfile_raw_1, regfile_raw_1_nxt;
   
   /*----------------------------------------------------------------------
    Check if read and write is being performed to same register in current 
    cycle? This is done by comparing the read and write IDXs.
    ----------------------------------------------------------------------*/
   always @(reg_write_enable_q_w or write_idx_w or instruction_f)
     begin
	if (reg_write_enable_q_w
	    && (write_idx_w == instruction_f[25:21]))
	  regfile_raw_0_nxt = 1'b1;
	else
	  regfile_raw_0_nxt = 1'b0;
	
	if (reg_write_enable_q_w
	    && (write_idx_w == instruction_f[20:16]))
	  regfile_raw_1_nxt = 1'b1;
	else
	  regfile_raw_1_nxt = 1'b0;
     end
   
   /*----------------------------------------------------------------------
    Select latched (delayed) write value or data from register file. If 
    read in previous cycle was performed to register written to in same
    cycle, then latched (delayed) write value is selected.
    ----------------------------------------------------------------------*/
   always @(regfile_raw_0 or w_result_d or regfile_data_0)
     if (regfile_raw_0)
       reg_data_live_0 = w_result_d;
     else
       reg_data_live_0 = regfile_data_0;
   
   /*----------------------------------------------------------------------
    Select latched (delayed) write value or data from register file. If 
    read in previous cycle was performed to register written to in same
    cycle, then latched (delayed) write value is selected.
    ----------------------------------------------------------------------*/
   always @(regfile_raw_1 or w_result_d or regfile_data_1)
     if (regfile_raw_1)
       reg_data_live_1 = w_result_d;
     else
       reg_data_live_1 = regfile_data_1;
   
   /*----------------------------------------------------------------------
    Latch value written to register file
    ----------------------------------------------------------------------*/
   always @(posedge clk_i `CFG_RESET_SENSITIVITY)
     if (rst_i == `TRUE)
       begin
	  regfile_raw_0 <= 1'b0;
	  regfile_raw_1 <= 1'b0;
	  w_result_d <= 32'b0;
       end
     else
       begin
	  regfile_raw_0 <= regfile_raw_0_nxt;
	  regfile_raw_1 <= regfile_raw_1_nxt;
	  w_result_d <= w_result;
       end
   
   /*----------------------------------------------------------------------
    Register file instantiation as Pseudo-Dual Port EBRs.
    ----------------------------------------------------------------------*/
   pmi_ram_dp
     #(
       // ----- Parameters -----
       .pmi_wr_addr_depth(1<<5),
       .pmi_wr_addr_width(5),
       .pmi_wr_data_width(32),
       .pmi_rd_addr_depth(1<<5),
       .pmi_rd_addr_width(5),
       .pmi_rd_data_width(32),
       .pmi_regmode("noreg"),
       .pmi_gsr("enable"),
       .pmi_resetmode("sync"),
       .pmi_init_file("none"),
       .pmi_init_file_format("binary"),
       .pmi_family(`LATTICE_FAMILY),
       .module_type("pmi_ram_dp")
       )
   reg_0
     (
      // ----- Inputs -----
      .Data(w_result),
      .WrAddress(write_idx_w),
      .RdAddress(instruction_f[25:21]),
      .WrClock(clk_i),
      .RdClock(clk_i),
      .WrClockEn(`TRUE),
      .RdClockEn(`TRUE),
      .WE(reg_write_enable_q_w),
      .Reset(rst_i), 
      // ----- Outputs -----
      .Q(regfile_data_0)
      );

   pmi_ram_dp
     #(
       // ----- Parameters -----
       .pmi_wr_addr_depth(1<<5),
       .pmi_wr_addr_width(5),
       .pmi_wr_data_width(32),
       .pmi_rd_addr_depth(1<<5),
       .pmi_rd_addr_width(5),
       .pmi_rd_data_width(32),
       .pmi_regmode("noreg"),
       .pmi_gsr("enable"),
       .pmi_resetmode("sync"),
       .pmi_init_file("none"),
       .pmi_init_file_format("binary"),
       .pmi_family(`LATTICE_FAMILY),
       .module_type("pmi_ram_dp")
       )
   reg_1
     (
      // ----- Inputs -----
      .Data(w_result),
      .WrAddress(write_idx_w),
      .RdAddress(instruction_f[20:16]),
      .WrClock(clk_i),
      .RdClock(clk_i),
      .WrClockEn(`TRUE),
      .RdClockEn(`TRUE),
      .WE(reg_write_enable_q_w),
      .Reset(rst_i), 
      // ----- Outputs -----
      .Q(regfile_data_1)
      );
`endif

`ifdef CFG_EBR_NEGEDGE_REGISTER_FILE
   pmi_ram_dp
     #(
       // ----- Parameters -----
       .pmi_wr_addr_depth(1<<5),
       .pmi_wr_addr_width(5),
       .pmi_wr_data_width(32),
       .pmi_rd_addr_depth(1<<5),
       .pmi_rd_addr_width(5),
       .pmi_rd_data_width(32),
       .pmi_regmode("noreg"),
       .pmi_gsr("enable"),
       .pmi_resetmode("sync"),
       .pmi_init_file("none"),
       .pmi_init_file_format("binary"),
       .pmi_family(`LATTICE_FAMILY),
       .module_type("pmi_ram_dp")
       )
   reg_0
     (
      // ----- Inputs -----
      .Data(w_result),
      .WrAddress(write_idx_w),
      .RdAddress(read_idx_0_d),
      .WrClock(clk_i),
      .RdClock(clk_n_i),
      .WrClockEn(`TRUE),
      .RdClockEn(stall_f == `FALSE),
      .WE(reg_write_enable_q_w),
      .Reset(rst_i), 
      // ----- Outputs -----
      .Q(reg_data_0)
      );
   
   pmi_ram_dp
     #(
       // ----- Parameters -----
       .pmi_wr_addr_depth(1<<5),
       .pmi_wr_addr_width(5),
       .pmi_wr_data_width(32),
       .pmi_rd_addr_depth(1<<5),
       .pmi_rd_addr_width(5),
       .pmi_rd_data_width(32),
       .pmi_regmode("noreg"),
       .pmi_gsr("enable"),
       .pmi_resetmode("sync"),
       .pmi_init_file("none"),
       .pmi_init_file_format("binary"),
       .pmi_family(`LATTICE_FAMILY),
       .module_type("pmi_ram_dp")
       )
   reg_1
     (
      // ----- Inputs -----
      .Data(w_result),
      .WrAddress(write_idx_w),
      .RdAddress(read_idx_1_d),
      .WrClock(clk_i),
      .RdClock(clk_n_i),
      .WrClockEn(`TRUE),
      .RdClockEn(stall_f == `FALSE),
      .WE(reg_write_enable_q_w),
      .Reset(rst_i), 
      // ----- Outputs -----
      .Q(reg_data_1)
      );
`endif


/////////////////////////////////////////////////////
// Combinational Logic
/////////////////////////////////////////////////////

`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
// Select between buffered and live data from register file
assign reg_data_0 = use_buf ? reg_data_buf_0 : reg_data_live_0;
assign reg_data_1 = use_buf ? reg_data_buf_1 : reg_data_live_1;
`endif
`ifdef LM32_EBR_REGISTER_FILE
`else
// Register file read ports
assign reg_data_0 = registers[read_idx_0_d];
assign reg_data_1 = registers[read_idx_1_d];
`endif

// Detect read-after-write hazzards
assign raw_x_0 = (write_idx_x == read_idx_0_d) && (write_enable_q_x == `TRUE);
assign raw_m_0 = (write_idx_m == read_idx_0_d) && (write_enable_q_m == `TRUE);
assign raw_w_0 = (write_idx_w == read_idx_0_d) && (write_enable_q_w == `TRUE);
assign raw_x_1 = (write_idx_x == read_idx_1_d) && (write_enable_q_x == `TRUE);
assign raw_m_1 = (write_idx_m == read_idx_1_d) && (write_enable_q_m == `TRUE);
assign raw_w_1 = (write_idx_w == read_idx_1_d) && (write_enable_q_w == `TRUE);

// Interlock detection - Raise an interlock for RAW hazzards 
always @(*)
begin
    if (   (   (x_bypass_enable_x == `FALSE)
            && (   ((read_enable_0_d == `TRUE) && (raw_x_0 == `TRUE))
                || ((read_enable_1_d == `TRUE) && (raw_x_1 == `TRUE))
               )
           )
        || (   (m_bypass_enable_m == `FALSE)
            && (   ((read_enable_0_d == `TRUE) && (raw_m_0 == `TRUE))
                || ((read_enable_1_d == `TRUE) && (raw_m_1 == `TRUE))
               )
           )
       )
        interlock = `TRUE;
    else
        interlock = `FALSE;
end

// Bypass for reg port 0
always @(*)
begin
    if (raw_x_0 == `TRUE)        
        bypass_data_0 = x_result;
    else if (raw_m_0 == `TRUE)
        bypass_data_0 = m_result;
    else if (raw_w_0 == `TRUE)
        bypass_data_0 = w_result;
    else
        bypass_data_0 = reg_data_0;
end

// Bypass for reg port 1
always @(*)
begin
    if (raw_x_1 == `TRUE)
        bypass_data_1 = x_result;
    else if (raw_m_1 == `TRUE)
        bypass_data_1 = m_result;
    else if (raw_w_1 == `TRUE)
        bypass_data_1 = w_result;
    else
        bypass_data_1 = reg_data_1;
end

   /*----------------------------------------------------------------------
    Branch prediction is performed in D stage of pipeline. Only PC-relative
    branches are predicted: forward-pointing conditional branches are not-
    taken, while backward-pointing conditional branches are taken. 
    Unconditional branches are always predicted taken!
    ----------------------------------------------------------------------*/
   assign branch_predict_d = bi_unconditional | bi_conditional;
   assign branch_predict_taken_d = bi_unconditional ? 1'b1 : (bi_conditional ? instruction_d[15] : 1'b0);
   
   // Compute branch target address: Branch PC PLUS Offset
   assign branch_target_d = pc_d + branch_offset_d;

   // Compute fetch address. Address of instruction sequentially after the
   // branch if branch is not taken. Target address of branch is branch is
   // taken
   assign branch_predict_address_d = branch_predict_taken_d ? branch_target_d : pc_f;

// D stage result selection
always @(*)
begin
    d_result_0 = d_result_sel_0_d[0] ? {pc_f, 2'b00} : bypass_data_0; 
    case (d_result_sel_1_d)
    `LM32_D_RESULT_SEL_1_ZERO:      d_result_1 = {`LM32_WORD_WIDTH{1'b0}};
    `LM32_D_RESULT_SEL_1_REG_1:     d_result_1 = bypass_data_1;
    `LM32_D_RESULT_SEL_1_IMMEDIATE: d_result_1 = immediate_d;
    default:                        d_result_1 = {`LM32_WORD_WIDTH{1'bx}};
    endcase
end

`ifdef CFG_USER_ENABLED    
// Operands for user-defined instructions
assign user_operand_0 = operand_0_x;
assign user_operand_1 = operand_1_x;
`endif

`ifdef CFG_SIGN_EXTEND_ENABLED
// Sign-extension
assign sextb_result_x = {{24{operand_0_x[7]}}, operand_0_x[7:0]};
assign sexth_result_x = {{16{operand_0_x[15]}}, operand_0_x[15:0]};
assign sext_result_x = size_x == `LM32_SIZE_BYTE ? sextb_result_x : sexth_result_x;
`endif

`ifdef LM32_NO_BARREL_SHIFT
// Only single bit shift operations are supported when barrel-shifter isn't implemented
assign shifter_result_x = {operand_0_x[`LM32_WORD_WIDTH-1] & sign_extend_x, operand_0_x[`LM32_WORD_WIDTH-1:1]};
`endif

// Condition evaluation
assign cmp_zero = operand_0_x == operand_1_x;
assign cmp_negative = adder_result_x[`LM32_WORD_WIDTH-1];
assign cmp_overflow = adder_overflow_x;
assign cmp_carry_n = adder_carry_n_x;
always @(*)
begin
    case (condition_x)
    `LM32_CONDITION_U1:   condition_met_x = `TRUE;
    `LM32_CONDITION_U2:   condition_met_x = `TRUE;
    `LM32_CONDITION_E:    condition_met_x = cmp_zero;
    `LM32_CONDITION_NE:   condition_met_x = !cmp_zero;
    `LM32_CONDITION_G:    condition_met_x = !cmp_zero && (cmp_negative == cmp_overflow);
    `LM32_CONDITION_GU:   condition_met_x = cmp_carry_n && !cmp_zero;
    `LM32_CONDITION_GE:   condition_met_x = cmp_negative == cmp_overflow;
    `LM32_CONDITION_GEU:  condition_met_x = cmp_carry_n;
    default:              condition_met_x = 1'bx;
    endcase 
end

// X stage result selection
always @(*)
begin
    x_result =   x_result_sel_add_x ? adder_result_x 
               : x_result_sel_csr_x ? csr_read_data_x
`ifdef CFG_SIGN_EXTEND_ENABLED
               : x_result_sel_sext_x ? sext_result_x
`endif
`ifdef CFG_USER_ENABLED
               : x_result_sel_user_x ? user_result
`endif
`ifdef LM32_NO_BARREL_SHIFT
               : x_result_sel_shift_x ? shifter_result_x
`endif
`ifdef LM32_MC_ARITHMETIC_ENABLED
               : x_result_sel_mc_arith_x ? mc_result_x
`endif
               : logic_result_x;
end

// M stage result selection
always @(*)
begin
    m_result =   m_result_sel_compare_m ? {{`LM32_WORD_WIDTH-1{1'b0}}, condition_met_m}
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
               : m_result_sel_shift_m ? shifter_result_m
`endif
               : operand_m; 
end

// W stage result selection
always @(*)
begin
    w_result =    w_result_sel_load_w ? load_data_w
`ifdef CFG_PL_MULTIPLY_ENABLED
                : w_result_sel_mul_w ? multiplier_result_w
`endif
                : operand_w;
end

`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
// Indicate when a branch should be taken in X stage
assign branch_taken_x =      (stall_x == `FALSE)
                          && (   (branch_x == `TRUE)
                              && ((condition_x == `LM32_CONDITION_U1) || (condition_x == `LM32_CONDITION_U2))
                              && (valid_x == `TRUE)
                              && (branch_predict_x == `FALSE)
                             ); 
`endif

// Indicate when a branch should be taken in M stage (exceptions are a type of branch)
assign branch_taken_m =      (stall_m == `FALSE) 
                          && (   (   (branch_m == `TRUE) 
                                  && (valid_m == `TRUE)
                                  && (   (   (condition_met_m == `TRUE)
					  && (branch_predict_taken_m == `FALSE)
					 )
				      || (   (condition_met_m == `FALSE)
					  && (branch_predict_m == `TRUE)
					  && (branch_predict_taken_m == `TRUE)
					 )
				     )
                                 ) 
                              || (exception_m == `TRUE)
                             );

// Indicate when a branch in M stage is mispredicted as being taken
assign branch_mispredict_taken_m =    (condition_met_m == `FALSE)
                                   && (branch_predict_m == `TRUE)
	   			   && (branch_predict_taken_m == `TRUE);
   
// Indicate when a branch in M stage will cause flush in X stage
assign branch_flushX_m =    (stall_m == `FALSE)
                         && (   (   (branch_m == `TRUE) 
                                 && (valid_m == `TRUE)
			         && (   (condition_met_m == `TRUE)
				     || (   (condition_met_m == `FALSE)
					 && (branch_predict_m == `TRUE)
					 && (branch_predict_taken_m == `TRUE)
					)
				    )
			        )
			     || (exception_m == `TRUE)
			    );

// Generate signal that will kill instructions in each pipeline stage when necessary
assign kill_f =    (   (valid_d == `TRUE)
                    && (branch_predict_taken_d == `TRUE)
		   )
                || (branch_taken_m == `TRUE) 
`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
                || (branch_taken_x == `TRUE)
`endif
`ifdef CFG_ICACHE_ENABLED
                || (icache_refill_request == `TRUE) 
`endif
`ifdef CFG_DCACHE_ENABLED                
                || (dcache_refill_request == `TRUE)
`endif
                ;
assign kill_d =    (branch_taken_m == `TRUE) 
`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
                || (branch_taken_x == `TRUE)
`endif
`ifdef CFG_ICACHE_ENABLED
                || (icache_refill_request == `TRUE)     
`endif                
`ifdef CFG_DCACHE_ENABLED                
                || (dcache_refill_request == `TRUE)
`endif
                ;
assign kill_x =    (branch_flushX_m == `TRUE) 
`ifdef CFG_DCACHE_ENABLED                
                || (dcache_refill_request == `TRUE)
`endif
                ;
assign kill_m =    `FALSE
`ifdef CFG_DCACHE_ENABLED                
                || (dcache_refill_request == `TRUE)
`endif
                ;                
assign kill_w =    `FALSE
`ifdef CFG_DCACHE_ENABLED                
                || (dcache_refill_request == `TRUE)
`endif                
                ;

// Exceptions

`ifdef CFG_DEBUG_ENABLED
assign breakpoint_exception =    (   (   (break_x == `TRUE)
				      || (bp_match == `TRUE)
				     )
				  && (valid_x == `TRUE)
				 )
`ifdef CFG_JTAG_ENABLED
                              || (jtag_break == `TRUE)
`endif
                              ;
`endif

`ifdef CFG_DEBUG_ENABLED
assign watchpoint_exception = wp_match == `TRUE;
`endif

`ifdef CFG_BUS_ERRORS_ENABLED
assign instruction_bus_error_exception = (   (bus_error_x == `TRUE)
                                          && (valid_x == `TRUE)
                                         );
assign data_bus_error_exception = data_bus_error_seen == `TRUE;
`endif

`ifdef CFG_MC_DIVIDE_ENABLED
assign divide_by_zero_exception = divide_by_zero_x == `TRUE;
`endif

assign system_call_exception = (   (scall_x == `TRUE)
`ifdef CFG_BUS_ERRORS_ENABLED
                                && (valid_x == `TRUE)
`endif
			       );

`ifdef CFG_DEBUG_ENABLED
assign debug_exception_x =  (breakpoint_exception == `TRUE)
                         || (watchpoint_exception == `TRUE)
                         ;

assign non_debug_exception_x = (system_call_exception == `TRUE)
`ifdef CFG_JTAG_ENABLED
                            || (reset_exception == `TRUE)
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
                            || (instruction_bus_error_exception == `TRUE)
                            || (data_bus_error_exception == `TRUE)
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
                            || (divide_by_zero_exception == `TRUE)
`endif
`ifdef CFG_INTERRUPTS_ENABLED
                            || (   (interrupt_exception == `TRUE)
`ifdef LM32_SINGLE_STEP_ENABLED
                                && (dc_ss == `FALSE)
`endif                            
`ifdef CFG_BUS_ERRORS_ENABLED
 				&& (store_q_m == `FALSE)
				&& (D_CYC_O == `FALSE)
`endif
                               )
`endif
                            ;

assign exception_x = (debug_exception_x == `TRUE) || (non_debug_exception_x == `TRUE);
`else
assign exception_x =           (system_call_exception == `TRUE)
`ifdef CFG_BUS_ERRORS_ENABLED
                            || (instruction_bus_error_exception == `TRUE)
                            || (data_bus_error_exception == `TRUE)
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
                            || (divide_by_zero_exception == `TRUE)
`endif
`ifdef CFG_INTERRUPTS_ENABLED
                            || (   (interrupt_exception == `TRUE)
`ifdef LM32_SINGLE_STEP_ENABLED
                                && (dc_ss == `FALSE)
`endif                            
`ifdef CFG_BUS_ERRORS_ENABLED
 				&& (store_q_m == `FALSE)
				&& (D_CYC_O == `FALSE)
`endif
                               )
`endif
                            ;
`endif

// Exception ID
always @(*)
begin
`ifdef CFG_DEBUG_ENABLED
`ifdef CFG_JTAG_ENABLED
    if (reset_exception == `TRUE)
        eid_x = `LM32_EID_RESET;
    else
`endif     
`ifdef CFG_BUS_ERRORS_ENABLED
         if (data_bus_error_exception == `TRUE)
        eid_x = `LM32_EID_DATA_BUS_ERROR;
    else
`endif
         if (breakpoint_exception == `TRUE)
        eid_x = `LM32_EID_BREAKPOINT;
    else
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
         if (data_bus_error_exception == `TRUE)
        eid_x = `LM32_EID_DATA_BUS_ERROR;
    else
         if (instruction_bus_error_exception == `TRUE)
        eid_x = `LM32_EID_INST_BUS_ERROR;
    else
`endif
`ifdef CFG_DEBUG_ENABLED
         if (watchpoint_exception == `TRUE)
        eid_x = `LM32_EID_WATCHPOINT;
    else 
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
         if (divide_by_zero_exception == `TRUE)
        eid_x = `LM32_EID_DIVIDE_BY_ZERO;
    else
`endif
`ifdef CFG_INTERRUPTS_ENABLED
         if (   (interrupt_exception == `TRUE)
`ifdef LM32_SINGLE_STEP_ENABLED
             && (dc_ss == `FALSE)
`endif                            
            )
        eid_x = `LM32_EID_INTERRUPT;
    else
`endif
        eid_x = `LM32_EID_SCALL;
end

// Stall generation

assign stall_a = (stall_f == `TRUE);
                
assign stall_f = (stall_d == `TRUE);
                
assign stall_d =   (stall_x == `TRUE) 
                || (   (interlock == `TRUE)
                    && (kill_d == `FALSE)
                   ) 
		|| (   (   (eret_d == `TRUE)
			|| (scall_d == `TRUE)
			|| (bus_error_d == `TRUE)
		       )
		    && (   (load_q_x == `TRUE)
			|| (load_q_m == `TRUE)
			|| (store_q_x == `TRUE)
			|| (store_q_m == `TRUE)
			|| (D_CYC_O == `TRUE)
		       )
                    && (kill_d == `FALSE)
		   )
`ifdef CFG_DEBUG_ENABLED
		|| (   (   (break_d == `TRUE)
			|| (bret_d == `TRUE)
		       )
		    && (   (load_q_x == `TRUE)
			|| (store_q_x == `TRUE)
			|| (load_q_m == `TRUE)
			|| (store_q_m == `TRUE)
			|| (D_CYC_O == `TRUE)
		       )
                    && (kill_d == `FALSE)
		   )
`endif                   
                || (   (csr_write_enable_d == `TRUE)
                    && (load_q_x == `TRUE)
                   )                      
                ;
                
assign stall_x =    (stall_m == `TRUE)
`ifdef LM32_MC_ARITHMETIC_ENABLED
                 || (   (mc_stall_request_x == `TRUE)
                     && (kill_x == `FALSE)
                    ) 
`endif
`ifdef CFG_IROM_ENABLED
                 // Stall load/store instruction in D stage if there is an ongoing store
                 // operation to instruction ROM in M stage
                 || (   (irom_stall_request_x == `TRUE)
		     && (   (load_d == `TRUE)
			 || (store_d == `TRUE)
			)
		    )
`endif
                 ;

assign stall_m =    (stall_wb_load == `TRUE)
`ifdef CFG_SIZE_OVER_SPEED
                 || (D_CYC_O == `TRUE)
`else
                 || (   (D_CYC_O == `TRUE)
                     && (   (store_m == `TRUE)
		         /*
			  Bug: Following loop does not allow interrupts to be services since
			  either D_CYC_O or store_m is always high during entire duration of
			  loop.
		          L1:	addi	r1, r1, 1
			  	sw	(r2,0), r1
			  	bi	L1
			  
			  Introduce a single-cycle stall when a wishbone cycle is in progress
			  and a new store instruction is in Execute stage and a interrupt
			  exception has occured. This stall will ensure that D_CYC_O and 
			  store_m will both be low for one cycle.
			  */
		         || ((store_x == `TRUE) && (interrupt_exception == `TRUE))
                         || (load_m == `TRUE)
                         || (load_x == `TRUE)
                        ) 
                    ) 
`endif                 
`ifdef CFG_DCACHE_ENABLED
                 || (dcache_stall_request == `TRUE)     // Need to stall in case a taken branch is in M stage and data cache is only being flush, so wont be restarted
`endif                                    
`ifdef CFG_ICACHE_ENABLED
                 || (icache_stall_request == `TRUE)     // Pipeline needs to be stalled otherwise branches may be lost
                 || ((I_CYC_O == `TRUE) && ((branch_m == `TRUE) || (exception_m == `TRUE))) 
`else
`ifdef CFG_IWB_ENABLED
                 || (I_CYC_O == `TRUE)            
`endif
`endif                               
`ifdef CFG_USER_ENABLED
                 || (   (user_valid == `TRUE)           // Stall whole pipeline, rather than just X stage, where the instruction is, so we don't have to worry about exceptions (maybe)
                     && (user_complete == `FALSE)
                    )
`endif
                 ;      

// Qualify state changing control signals
`ifdef LM32_MC_ARITHMETIC_ENABLED
assign q_d = (valid_d == `TRUE) && (kill_d == `FALSE);
`endif
`ifdef CFG_MC_BARREL_SHIFT_ENABLED
assign shift_left_q_d = (shift_left_d == `TRUE) && (q_d == `TRUE);
assign shift_right_q_d = (shift_right_d == `TRUE) && (q_d == `TRUE);
`endif
`ifdef CFG_MC_MULTIPLY_ENABLED
assign multiply_q_d = (multiply_d == `TRUE) && (q_d == `TRUE);
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
assign divide_q_d = (divide_d == `TRUE) && (q_d == `TRUE);
assign modulus_q_d = (modulus_d == `TRUE) && (q_d == `TRUE);
`endif
assign q_x = (valid_x == `TRUE) && (kill_x == `FALSE);
assign csr_write_enable_q_x = (csr_write_enable_x == `TRUE) && (q_x == `TRUE);
assign eret_q_x = (eret_x == `TRUE) && (q_x == `TRUE);
`ifdef CFG_DEBUG_ENABLED
assign bret_q_x = (bret_x == `TRUE) && (q_x == `TRUE);
`endif
assign load_q_x = (load_x == `TRUE) 
               && (q_x == `TRUE)
`ifdef CFG_DEBUG_ENABLED
               && (bp_match == `FALSE)
`endif
                  ;
assign store_q_x = (store_x == `TRUE) 
               && (q_x == `TRUE)
`ifdef CFG_DEBUG_ENABLED
               && (bp_match == `FALSE)
`endif
                  ;
`ifdef CFG_USER_ENABLED
assign user_valid = (x_result_sel_user_x == `TRUE) && (q_x == `TRUE);
`endif                              
assign q_m = (valid_m == `TRUE) && (kill_m == `FALSE) && (exception_m == `FALSE);
assign load_q_m = (load_m == `TRUE) && (q_m == `TRUE);
assign store_q_m = (store_m == `TRUE) && (q_m == `TRUE);
`ifdef CFG_DEBUG_ENABLED
assign debug_exception_q_w = ((debug_exception_w == `TRUE) && (valid_w == `TRUE));
assign non_debug_exception_q_w = ((non_debug_exception_w == `TRUE) && (valid_w == `TRUE));        
`else
assign exception_q_w = ((exception_w == `TRUE) && (valid_w == `TRUE));        
`endif
// Don't qualify register write enables with kill, as the signal is needed early, and it doesn't matter if the instruction is killed (except for the actual write - but that is handled separately)
assign write_enable_q_x = (write_enable_x == `TRUE) && (valid_x == `TRUE) && (branch_flushX_m == `FALSE);
assign write_enable_q_m = (write_enable_m == `TRUE) && (valid_m == `TRUE);
assign write_enable_q_w = (write_enable_w == `TRUE) && (valid_w == `TRUE);
// The enable that actually does write the registers needs to be qualified with kill
assign reg_write_enable_q_w = (write_enable_w == `TRUE) && (kill_w == `FALSE) && (valid_w == `TRUE);

// Configuration (CFG) CSR
assign cfg = {
              `LM32_REVISION,
              watchpoints[3:0],
              breakpoints[3:0],
              interrupts[5:0],
`ifdef CFG_JTAG_UART_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_ROM_DEBUG_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_HW_DEBUG_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_DEBUG_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_ICACHE_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_DCACHE_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_CYCLE_COUNTER_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_USER_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_SIGN_EXTEND_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef LM32_BARREL_SHIFT_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef CFG_MC_DIVIDE_ENABLED
              `TRUE,
`else
              `FALSE,
`endif
`ifdef LM32_MULTIPLY_ENABLED 
              `TRUE
`else
              `FALSE
`endif
              };

assign cfg2 = {
		     30'b0,
`ifdef CFG_IROM_ENABLED
		     `TRUE,
`else
		     `FALSE,
`endif
`ifdef CFG_DRAM_ENABLED
		     `TRUE
`else
		     `FALSE
`endif
		     };
   
// Cache flush
`ifdef CFG_ICACHE_ENABLED
assign iflush =    (csr_write_enable_d == `TRUE) 
                && (csr_d == `LM32_CSR_ICC)
                && (stall_d == `FALSE)
                && (kill_d == `FALSE)
                && (valid_d == `TRUE);
`endif 
`ifdef CFG_DCACHE_ENABLED
assign dflush_x =  (csr_write_enable_q_x == `TRUE) 
                && (csr_x == `LM32_CSR_DCC);
`endif 

// Extract CSR index
assign csr_d = read_idx_0_d[`LM32_CSR_RNG];

// CSR reads
always @(*)
begin
    case (csr_x)
`ifdef CFG_INTERRUPTS_ENABLED
    `LM32_CSR_IE,
    `LM32_CSR_IM,
    `LM32_CSR_IP:   csr_read_data_x = interrupt_csr_read_data_x;  
`endif
`ifdef CFG_CYCLE_COUNTER_ENABLED
    `LM32_CSR_CC:   csr_read_data_x = cc;
`endif
    `LM32_CSR_CFG:  csr_read_data_x = cfg;
    `LM32_CSR_EBA:  csr_read_data_x = {eba, 8'h00};
`ifdef CFG_DEBUG_ENABLED
    `LM32_CSR_DEBA: csr_read_data_x = {deba, 8'h00};
`endif
`ifdef CFG_JTAG_UART_ENABLED
    `LM32_CSR_JTX:  csr_read_data_x = jtx_csr_read_data;  
    `LM32_CSR_JRX:  csr_read_data_x = jrx_csr_read_data;
`endif
    `LM32_CSR_CFG2: csr_read_data_x = cfg2;
      
    default:        csr_read_data_x = {`LM32_WORD_WIDTH{1'bx}};
    endcase
end

/////////////////////////////////////////////////////
// Sequential Logic
/////////////////////////////////////////////////////

// Exception Base Address (EBA) CSR
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
        eba <= eba_reset[`LM32_PC_WIDTH+2-1:8];
    else
    begin
        if ((csr_write_enable_q_x == `TRUE) && (csr_x == `LM32_CSR_EBA) && (stall_x == `FALSE))
            eba <= operand_1_x[`LM32_PC_WIDTH+2-1:8];
`ifdef CFG_HW_DEBUG_ENABLED
        if ((jtag_csr_write_enable == `TRUE) && (jtag_csr == `LM32_CSR_EBA))
            eba <= jtag_csr_write_data[`LM32_PC_WIDTH+2-1:8];
`endif
    end
end

`ifdef CFG_DEBUG_ENABLED
// Debug Exception Base Address (DEBA) CSR
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
        deba <= deba_reset[`LM32_PC_WIDTH+2-1:8];
    else
    begin
        if ((csr_write_enable_q_x == `TRUE) && (csr_x == `LM32_CSR_DEBA) && (stall_x == `FALSE))
            deba <= operand_1_x[`LM32_PC_WIDTH+2-1:8];
`ifdef CFG_HW_DEBUG_ENABLED
        if ((jtag_csr_write_enable == `TRUE) && (jtag_csr == `LM32_CSR_DEBA))
            deba <= jtag_csr_write_data[`LM32_PC_WIDTH+2-1:8];
`endif
    end
end
`endif

// Cycle Counter (CC) CSR
`ifdef CFG_CYCLE_COUNTER_ENABLED
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
        cc <= {`LM32_WORD_WIDTH{1'b0}};
    else
        cc <= cc + 1'b1;
end
`endif

`ifdef CFG_BUS_ERRORS_ENABLED
// Watch for data bus errors
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
        data_bus_error_seen <= `FALSE;
    else
    begin
        // Set flag when bus error is detected
        if ((D_ERR_I == `TRUE) && (D_CYC_O == `TRUE))
            data_bus_error_seen <= `TRUE;
        // Clear flag when exception is taken
        if ((exception_m == `TRUE) && (kill_m == `FALSE))
            data_bus_error_seen <= `FALSE;
    end
end
`endif
 
// Valid bits to indicate whether an instruction in a partcular pipeline stage is valid or not  

`ifdef CFG_ICACHE_ENABLED
`ifdef CFG_DCACHE_ENABLED
always @(*)
begin
    if (   (icache_refill_request == `TRUE) 
        || (dcache_refill_request == `TRUE)
       )
        valid_a = `FALSE;
    else if (   (icache_restart_request == `TRUE) 
             || (dcache_restart_request == `TRUE) 
            ) 
        valid_a = `TRUE;
    else 
        valid_a = !icache_refilling && !dcache_refilling;
end 
`else
always @(*)
begin
    if (icache_refill_request == `TRUE) 
        valid_a = `FALSE;
    else if (icache_restart_request == `TRUE) 
        valid_a = `TRUE;
    else 
        valid_a = !icache_refilling;
end 
`endif
`else
`ifdef CFG_DCACHE_ENABLED
always @(*)
begin
    if (dcache_refill_request == `TRUE) 
        valid_a = `FALSE;
    else if (dcache_restart_request == `TRUE) 
        valid_a = `TRUE;
    else 
        valid_a = !dcache_refilling;
end 
`endif
`endif

always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
    begin
        valid_f <= `FALSE;
        valid_d <= `FALSE;
        valid_x <= `FALSE;
        valid_m <= `FALSE;
        valid_w <= `FALSE;
    end
    else
    begin    
        if ((kill_f == `TRUE) || (stall_a == `FALSE))
`ifdef LM32_CACHE_ENABLED
            valid_f <= valid_a;    
`else
            valid_f <= `TRUE;
`endif            
        else if (stall_f == `FALSE)
            valid_f <= `FALSE;            

        if (kill_d == `TRUE)
            valid_d <= `FALSE;
        else if (stall_f == `FALSE)
            valid_d <= valid_f & !kill_f;
        else if (stall_d == `FALSE)
            valid_d <= `FALSE;
       
        if (stall_d == `FALSE)
            valid_x <= valid_d & !kill_d;
        else if (kill_x == `TRUE)
            valid_x <= `FALSE;
        else if (stall_x == `FALSE)
            valid_x <= `FALSE;

        if (kill_m == `TRUE)
            valid_m <= `FALSE;
        else if (stall_x == `FALSE)
            valid_m <= valid_x & !kill_x;
        else if (stall_m == `FALSE)
            valid_m <= `FALSE;

        if (stall_m == `FALSE)
            valid_w <= valid_m & !kill_m;
        else 
            valid_w <= `FALSE;        
    end
end

// Microcode pipeline registers
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
    begin
`ifdef CFG_USER_ENABLED
        user_opcode <= {`LM32_USER_OPCODE_WIDTH{1'b0}};       
`endif        
        operand_0_x <= {`LM32_WORD_WIDTH{1'b0}};
        operand_1_x <= {`LM32_WORD_WIDTH{1'b0}};
        store_operand_x <= {`LM32_WORD_WIDTH{1'b0}};
        branch_target_x <= {`LM32_WORD_WIDTH{1'b0}};        
        x_result_sel_csr_x <= `FALSE;
`ifdef LM32_MC_ARITHMETIC_ENABLED
        x_result_sel_mc_arith_x <= `FALSE;
`endif
`ifdef LM32_NO_BARREL_SHIFT    
        x_result_sel_shift_x <= `FALSE;
`endif
`ifdef CFG_SIGN_EXTEND_ENABLED
        x_result_sel_sext_x <= `FALSE;
`endif    
        x_result_sel_logic_x <= `FALSE;
`ifdef CFG_USER_ENABLED
        x_result_sel_user_x <= `FALSE;
`endif
        x_result_sel_add_x <= `FALSE;
        m_result_sel_compare_x <= `FALSE;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
        m_result_sel_shift_x <= `FALSE;
`endif    
        w_result_sel_load_x <= `FALSE;
`ifdef CFG_PL_MULTIPLY_ENABLED
        w_result_sel_mul_x <= `FALSE;
`endif
        x_bypass_enable_x <= `FALSE;
        m_bypass_enable_x <= `FALSE;
        write_enable_x <= `FALSE;
        write_idx_x <= {`LM32_REG_IDX_WIDTH{1'b0}};
        csr_x <= {`LM32_CSR_WIDTH{1'b0}};
        load_x <= `FALSE;
        store_x <= `FALSE;
        size_x <= {`LM32_SIZE_WIDTH{1'b0}};
        sign_extend_x <= `FALSE;
        adder_op_x <= `FALSE;
        adder_op_x_n <= `FALSE;
        logic_op_x <= 4'h0;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
        direction_x <= `FALSE;
`endif
`ifdef CFG_ROTATE_ENABLED
        rotate_x <= `FALSE;

`endif
        branch_x <= `FALSE;
        branch_predict_x <= `FALSE;
        branch_predict_taken_x <= `FALSE;
        condition_x <= `LM32_CONDITION_U1;
`ifdef CFG_DEBUG_ENABLED
        break_x <= `FALSE;
`endif
        scall_x <= `FALSE;
        eret_x <= `FALSE;
`ifdef CFG_DEBUG_ENABLED
        bret_x <= `FALSE;
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
        bus_error_x <= `FALSE;
        data_bus_error_exception_m <= `FALSE;
`endif
        csr_write_enable_x <= `FALSE;
        operand_m <= {`LM32_WORD_WIDTH{1'b0}};
        branch_target_m <= {`LM32_WORD_WIDTH{1'b0}};
        m_result_sel_compare_m <= `FALSE;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
        m_result_sel_shift_m <= `FALSE;
`endif    
        w_result_sel_load_m <= `FALSE;
`ifdef CFG_PL_MULTIPLY_ENABLED
        w_result_sel_mul_m <= `FALSE;
`endif
        m_bypass_enable_m <= `FALSE;
        branch_m <= `FALSE;
        branch_predict_m <= `FALSE;
	branch_predict_taken_m <= `FALSE;
        exception_m <= `FALSE;
        load_m <= `FALSE;
        store_m <= `FALSE;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
        direction_m <= `FALSE;
`endif
        write_enable_m <= `FALSE;            
        write_idx_m <= {`LM32_REG_IDX_WIDTH{1'b0}};
        condition_met_m <= `FALSE;
`ifdef CFG_DCACHE_ENABLED
        dflush_m <= `FALSE;
`endif
`ifdef CFG_DEBUG_ENABLED
        debug_exception_m <= `FALSE;
        non_debug_exception_m <= `FALSE;        
`endif
        operand_w <= {`LM32_WORD_WIDTH{1'b0}};        
        w_result_sel_load_w <= `FALSE;
`ifdef CFG_PL_MULTIPLY_ENABLED
        w_result_sel_mul_w <= `FALSE;
`endif
        write_idx_w <= {`LM32_REG_IDX_WIDTH{1'b0}};        
        write_enable_w <= `FALSE;
`ifdef CFG_DEBUG_ENABLED
        debug_exception_w <= `FALSE;
        non_debug_exception_w <= `FALSE;        
`else
        exception_w <= `FALSE;
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
        memop_pc_w <= {`LM32_PC_WIDTH{1'b0}};
`endif
    end
    else
    begin
        // D/X stage registers
       
        if (stall_x == `FALSE)
        begin
`ifdef CFG_USER_ENABLED
            user_opcode <= user_opcode_d;       
`endif        
            operand_0_x <= d_result_0;
            operand_1_x <= d_result_1;
            store_operand_x <= bypass_data_1;
            branch_target_x <= branch_reg_d == `TRUE ? bypass_data_0[`LM32_PC_RNG] : branch_target_d;            
            x_result_sel_csr_x <= x_result_sel_csr_d;
`ifdef LM32_MC_ARITHMETIC_ENABLED
            x_result_sel_mc_arith_x <= x_result_sel_mc_arith_d;
`endif
`ifdef LM32_NO_BARREL_SHIFT    
            x_result_sel_shift_x <= x_result_sel_shift_d;
`endif
`ifdef CFG_SIGN_EXTEND_ENABLED
            x_result_sel_sext_x <= x_result_sel_sext_d;
`endif    
            x_result_sel_logic_x <= x_result_sel_logic_d;
`ifdef CFG_USER_ENABLED
            x_result_sel_user_x <= x_result_sel_user_d;
`endif
            x_result_sel_add_x <= x_result_sel_add_d;
            m_result_sel_compare_x <= m_result_sel_compare_d;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
            m_result_sel_shift_x <= m_result_sel_shift_d;
`endif    
            w_result_sel_load_x <= w_result_sel_load_d;
`ifdef CFG_PL_MULTIPLY_ENABLED
            w_result_sel_mul_x <= w_result_sel_mul_d;
`endif
            x_bypass_enable_x <= x_bypass_enable_d;
            m_bypass_enable_x <= m_bypass_enable_d;
            load_x <= load_d;
            store_x <= store_d;
            branch_x <= branch_d;
	    branch_predict_x <= branch_predict_d;
	    branch_predict_taken_x <= branch_predict_taken_d;
	    write_idx_x <= write_idx_d;
            csr_x <= csr_d;
            size_x <= size_d;
            sign_extend_x <= sign_extend_d;
            adder_op_x <= adder_op_d;
            adder_op_x_n <= ~adder_op_d;
            logic_op_x <= logic_op_d;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
            direction_x <= direction_d;
`endif
`ifdef CFG_ROTATE_ENABLED
            rotate_x <= rotate_d;
`endif
            condition_x <= condition_d;
            csr_write_enable_x <= csr_write_enable_d;
`ifdef CFG_DEBUG_ENABLED
            break_x <= break_d;
`endif
            scall_x <= scall_d;
`ifdef CFG_BUS_ERRORS_ENABLED
            bus_error_x <= bus_error_d;
`endif
            eret_x <= eret_d;
`ifdef CFG_DEBUG_ENABLED
            bret_x <= bret_d; 
`endif
            write_enable_x <= write_enable_d;
        end
        
        // X/M stage registers

        if (stall_m == `FALSE)
        begin
            operand_m <= x_result;
            m_result_sel_compare_m <= m_result_sel_compare_x;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
            m_result_sel_shift_m <= m_result_sel_shift_x;
`endif    
            if (exception_x == `TRUE)
            begin
                w_result_sel_load_m <= `FALSE;
`ifdef CFG_PL_MULTIPLY_ENABLED
                w_result_sel_mul_m <= `FALSE;
`endif
            end
            else
            begin
                w_result_sel_load_m <= w_result_sel_load_x;
`ifdef CFG_PL_MULTIPLY_ENABLED
                w_result_sel_mul_m <= w_result_sel_mul_x;
`endif
            end
            m_bypass_enable_m <= m_bypass_enable_x;
`ifdef CFG_PL_BARREL_SHIFT_ENABLED
            direction_m <= direction_x;
`endif
            load_m <= load_x;
            store_m <= store_x;
`ifdef CFG_FAST_UNCONDITIONAL_BRANCH    
            branch_m <= branch_x && !branch_taken_x;
`else
            branch_m <= branch_x;
	    branch_predict_m <= branch_predict_x;
	    branch_predict_taken_m <= branch_predict_taken_x;
`endif
`ifdef CFG_DEBUG_ENABLED
	   // Data bus errors are generated by the wishbone and are
	   // made known to the processor only in next cycle (as a
	   // non-debug exception). A break instruction can be seen
	   // in same cycle (causing a debug exception). Handle non
	   // -debug exception first!
            if (non_debug_exception_x == `TRUE) 
                write_idx_m <= `LM32_EA_REG;
            else if (debug_exception_x == `TRUE)
                write_idx_m <= `LM32_BA_REG;
            else 
                write_idx_m <= write_idx_x;
`else
            if (exception_x == `TRUE)
                write_idx_m <= `LM32_EA_REG;
            else 
                write_idx_m <= write_idx_x;
`endif
            condition_met_m <= condition_met_x;
`ifdef CFG_DEBUG_ENABLED
	   if (exception_x == `TRUE)
	     if ((dc_re == `TRUE)
		 || ((debug_exception_x == `TRUE) 
		     && (non_debug_exception_x == `FALSE)))
	       branch_target_m <= {deba, eid_x, {3{1'b0}}};
	     else
	       branch_target_m <= {eba, eid_x, {3{1'b0}}};
	   else
	     branch_target_m <= branch_target_x;
`else
            branch_target_m <= exception_x == `TRUE ? {eba, eid_x, {3{1'b0}}} : branch_target_x;
`endif
`ifdef CFG_TRACE_ENABLED
            eid_m <= eid_x;
`endif
`ifdef CFG_DCACHE_ENABLED
            dflush_m <= dflush_x;
`endif
            eret_m <= eret_q_x;
`ifdef CFG_DEBUG_ENABLED
            bret_m <= bret_q_x; 
`endif
            write_enable_m <= exception_x == `TRUE ? `TRUE : write_enable_x;            
`ifdef CFG_DEBUG_ENABLED
            debug_exception_m <= debug_exception_x;
            non_debug_exception_m <= non_debug_exception_x;        
`endif
        end
        
        // State changing regs
        if (stall_m == `FALSE)
        begin
            if ((exception_x == `TRUE) && (q_x == `TRUE) && (stall_x == `FALSE))
                exception_m <= `TRUE;
            else 
                exception_m <= `FALSE;
`ifdef CFG_BUS_ERRORS_ENABLED
	   data_bus_error_exception_m <=    (data_bus_error_exception == `TRUE) 
`ifdef CFG_DEBUG_ENABLED
					 && (reset_exception == `FALSE)
`endif
					 ;
`endif
	end
                
        // M/W stage registers
`ifdef CFG_BUS_ERRORS_ENABLED
        operand_w <= exception_m == `TRUE ? (data_bus_error_exception_m ? {memop_pc_w, 2'b00} : {pc_m, 2'b00}) : m_result;
`else
        operand_w <= exception_m == `TRUE ? {pc_m, 2'b00} : m_result;
`endif
        w_result_sel_load_w <= w_result_sel_load_m;
`ifdef CFG_PL_MULTIPLY_ENABLED
        w_result_sel_mul_w <= w_result_sel_mul_m;
`endif
        write_idx_w <= write_idx_m;
`ifdef CFG_TRACE_ENABLED
        eid_w <= eid_m;
        eret_w <= eret_m;
`ifdef CFG_DEBUG_ENABLED
        bret_w <= bret_m; 
`endif
`endif
        write_enable_w <= write_enable_m;
`ifdef CFG_DEBUG_ENABLED
        debug_exception_w <= debug_exception_m;
        non_debug_exception_w <= non_debug_exception_m;
`else
        exception_w <= exception_m;
`endif
`ifdef CFG_BUS_ERRORS_ENABLED
        if (   (stall_m == `FALSE)
            && (   (load_q_m == `TRUE) 
                || (store_q_m == `TRUE)
               )
	   )
          memop_pc_w <= pc_m;
`endif
    end
end

`ifdef CFG_EBR_POSEDGE_REGISTER_FILE
// Buffer data read from register file, in case a stall occurs, and watch for
// any writes to the modified registers
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
    begin
        use_buf <= `FALSE;
        reg_data_buf_0 <= {`LM32_WORD_WIDTH{1'b0}};
        reg_data_buf_1 <= {`LM32_WORD_WIDTH{1'b0}};
    end
    else
    begin
        if (stall_d == `FALSE)
            use_buf <= `FALSE;
        else if (use_buf == `FALSE)
        begin        
            reg_data_buf_0 <= reg_data_live_0;
            reg_data_buf_1 <= reg_data_live_1;
            use_buf <= `TRUE;
        end        
        if (reg_write_enable_q_w == `TRUE)
        begin
            if (write_idx_w == read_idx_0_d)
                reg_data_buf_0 <= w_result;
            if (write_idx_w == read_idx_1_d)
                reg_data_buf_1 <= w_result;
        end
    end
end
`endif

`ifdef LM32_EBR_REGISTER_FILE
`else
// Register file write port
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE) begin
        registers[0] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[1] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[2] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[3] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[4] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[5] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[6] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[7] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[8] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[9] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[10] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[11] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[12] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[13] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[14] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[15] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[16] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[17] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[18] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[19] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[20] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[21] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[22] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[23] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[24] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[25] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[26] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[27] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[28] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[29] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[30] <= {`LM32_WORD_WIDTH{1'b0}};
        registers[31] <= {`LM32_WORD_WIDTH{1'b0}}; 
        end
    else begin
        if (reg_write_enable_q_w == `TRUE)
          registers[write_idx_w] <= w_result;
        end
end
`endif

`ifdef CFG_TRACE_ENABLED
// PC tracing logic
always @(posedge clk_i `CFG_RESET_SENSITIVITY)
begin
    if (rst_i == `TRUE)
    begin
        trace_pc_valid <= `FALSE;
        trace_pc <= {`LM32_PC_WIDTH{1'b0}};
        trace_exception <= `FALSE;
        trace_eid <= `LM32_EID_RESET;
        trace_eret <= `FALSE;
`ifdef CFG_DEBUG_ENABLED
        trace_bret <= `FALSE;
`endif
        pc_c <= `CFG_EBA_RESET/4;
    end
    else
    begin
        trace_pc_valid <= `FALSE;
        // Has an exception occured
`ifdef CFG_DEBUG_ENABLED
        if ((debug_exception_q_w == `TRUE) || (non_debug_exception_q_w == `TRUE))
`else
        if (exception_q_w == `TRUE)
`endif
        begin        
            trace_exception <= `TRUE;
            trace_pc_valid <= `TRUE;
            trace_pc <= pc_w;
            trace_eid <= eid_w;
        end
        else
            trace_exception <= `FALSE;
        
        if ((valid_w == `TRUE) && (!kill_w))
        begin
            // An instruction is commiting. Determine if it is non-sequential
            if (pc_c + 1'b1 != pc_w)
            begin
                // Non-sequential instruction
                trace_pc_valid <= `TRUE;
                trace_pc <= pc_w;
            end
            // Record PC so we can determine if next instruction is sequential or not
            pc_c <= pc_w;
            // Indicate if it was an eret/bret instruction
            trace_eret <= eret_w;
`ifdef CFG_DEBUG_ENABLED
            trace_bret <= bret_w;
`endif
        end
        else
        begin
            trace_eret <= `FALSE;
`ifdef CFG_DEBUG_ENABLED
            trace_bret <= `FALSE;
`endif
        end
    end
end
`endif
      
/////////////////////////////////////////////////////
// Behavioural Logic
/////////////////////////////////////////////////////

// synthesis translate_off            

// Reset register 0. Only needed for simulation. 
initial
begin
`ifdef LM32_EBR_REGISTER_FILE
    reg_0.mem[0] = {`LM32_WORD_WIDTH{1'b0}};
    reg_1.mem[0] = {`LM32_WORD_WIDTH{1'b0}};
`else
    registers[0] = {`LM32_WORD_WIDTH{1'b0}};
`endif
end

// synthesis translate_on
        
endmodule