1.1 --- a/lm32_shifter.v Sun Mar 06 21:17:31 2011 +0000 1.2 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 1.3 @@ -1,134 +0,0 @@ 1.4 -// ============================================================================= 1.5 -// COPYRIGHT NOTICE 1.6 -// Copyright 2006 (c) Lattice Semiconductor Corporation 1.7 -// ALL RIGHTS RESERVED 1.8 -// This confidential and proprietary software may be used only as authorised by 1.9 -// a licensing agreement from Lattice Semiconductor Corporation. 1.10 -// The entire notice above must be reproduced on all authorized copies and 1.11 -// copies may only be made to the extent permitted by a licensing agreement from 1.12 -// Lattice Semiconductor Corporation. 1.13 -// 1.14 -// Lattice Semiconductor Corporation TEL : 1-800-Lattice (USA and Canada) 1.15 -// 5555 NE Moore Court 408-826-6000 (other locations) 1.16 -// Hillsboro, OR 97124 web : http://www.latticesemi.com/ 1.17 -// U.S.A email: techsupport@latticesemi.com 1.18 -// =============================================================================/ 1.19 -// FILE DETAILS 1.20 -// Project : LatticeMico32 1.21 -// File : lm32_shifter.v 1.22 -// Title : Barrel shifter 1.23 -// Dependencies : lm32_include.v 1.24 -// Version : 6.1.17 1.25 -// : Initial Release 1.26 -// Version : 7.0SP2, 3.0 1.27 -// : No Change 1.28 -// Version : 3.1 1.29 -// : No Change 1.30 -// ============================================================================= 1.31 - 1.32 -`include "lm32_include.v" 1.33 - 1.34 -///////////////////////////////////////////////////// 1.35 -// Module interface 1.36 -///////////////////////////////////////////////////// 1.37 - 1.38 -module lm32_shifter ( 1.39 - // ----- Inputs ------- 1.40 - clk_i, 1.41 - rst_i, 1.42 - stall_x, 1.43 - direction_x, 1.44 - sign_extend_x, 1.45 - operand_0_x, 1.46 - operand_1_x, 1.47 - // ----- Outputs ------- 1.48 - shifter_result_m 1.49 - ); 1.50 - 1.51 -///////////////////////////////////////////////////// 1.52 -// Inputs 1.53 -///////////////////////////////////////////////////// 1.54 - 1.55 -input clk_i; // Clock 1.56 -input rst_i; // Reset 1.57 -input stall_x; // Stall instruction in X stage 1.58 -input direction_x; // Direction to shift 1.59 -input sign_extend_x; // Whether shift is arithmetic (1'b1) or logical (1'b0) 1.60 -input [`LM32_WORD_RNG] operand_0_x; // Operand to shift 1.61 -input [`LM32_WORD_RNG] operand_1_x; // Operand that specifies how many bits to shift by 1.62 - 1.63 -///////////////////////////////////////////////////// 1.64 -// Outputs 1.65 -///////////////////////////////////////////////////// 1.66 - 1.67 -output [`LM32_WORD_RNG] shifter_result_m; // Result of shift 1.68 -wire [`LM32_WORD_RNG] shifter_result_m; 1.69 - 1.70 -///////////////////////////////////////////////////// 1.71 -// Internal nets and registers 1.72 -///////////////////////////////////////////////////// 1.73 - 1.74 -reg direction_m; 1.75 -reg [`LM32_WORD_RNG] left_shift_result; 1.76 -reg [`LM32_WORD_RNG] right_shift_result; 1.77 -reg [`LM32_WORD_RNG] left_shift_operand; 1.78 -wire [`LM32_WORD_RNG] right_shift_operand; 1.79 -wire fill_value; 1.80 -wire [`LM32_WORD_RNG] right_shift_in; 1.81 - 1.82 -integer shift_idx_0; 1.83 -integer shift_idx_1; 1.84 - 1.85 -///////////////////////////////////////////////////// 1.86 -// Combinational Logic 1.87 -///////////////////////////////////////////////////// 1.88 - 1.89 -// Select operands - To perform a left shift, we reverse the bits and perform a right shift 1.90 -always @(*) 1.91 -begin 1.92 - for (shift_idx_0 = 0; shift_idx_0 < `LM32_WORD_WIDTH; shift_idx_0 = shift_idx_0 + 1) 1.93 - left_shift_operand[`LM32_WORD_WIDTH-1-shift_idx_0] = operand_0_x[shift_idx_0]; 1.94 -end 1.95 -assign right_shift_operand = direction_x == `LM32_SHIFT_OP_LEFT ? left_shift_operand : operand_0_x; 1.96 - 1.97 -// Determine fill value for right shift - Sign bit for arithmetic shift, or zero for logical shift 1.98 -assign fill_value = (sign_extend_x == `TRUE) && (direction_x == `LM32_SHIFT_OP_RIGHT) 1.99 - ? operand_0_x[`LM32_WORD_WIDTH-1] 1.100 - : 1'b0; 1.101 - 1.102 -// Determine bits to shift in for right shift or rotate 1.103 -assign right_shift_in = {`LM32_WORD_WIDTH{fill_value}}; 1.104 - 1.105 -// Reverse bits to get left shift result 1.106 -always @(*) 1.107 -begin 1.108 - for (shift_idx_1 = 0; shift_idx_1 < `LM32_WORD_WIDTH; shift_idx_1 = shift_idx_1 + 1) 1.109 - left_shift_result[`LM32_WORD_WIDTH-1-shift_idx_1] = right_shift_result[shift_idx_1]; 1.110 -end 1.111 - 1.112 -// Select result 1.113 -assign shifter_result_m = direction_m == `LM32_SHIFT_OP_LEFT ? left_shift_result : right_shift_result; 1.114 - 1.115 -///////////////////////////////////////////////////// 1.116 -// Sequential Logic 1.117 -///////////////////////////////////////////////////// 1.118 - 1.119 -// Perform right shift 1.120 -always @(posedge clk_i `CFG_RESET_SENSITIVITY) 1.121 -begin 1.122 - if (rst_i == `TRUE) 1.123 - begin 1.124 - right_shift_result <= {`LM32_WORD_WIDTH{1'b0}}; 1.125 - direction_m <= `FALSE; 1.126 - end 1.127 - else 1.128 - begin 1.129 - if (stall_x == `FALSE) 1.130 - begin 1.131 - right_shift_result <= {right_shift_in, right_shift_operand} >> operand_1_x[`LM32_SHIFT_RNG]; 1.132 - direction_m <= direction_x; 1.133 - end 1.134 - end 1.135 -end 1.136 - 1.137 -endmodule