Sun, 04 Apr 2010 20:40:03 +0100
add lm32 source
| philpem@0 | 1 | // ============================================================================= |
| philpem@0 | 2 | // COPYRIGHT NOTICE |
| philpem@0 | 3 | // Copyright 2006 (c) Lattice Semiconductor Corporation |
| philpem@0 | 4 | // ALL RIGHTS RESERVED |
| philpem@0 | 5 | // This confidential and proprietary software may be used only as authorised by |
| philpem@0 | 6 | // a licensing agreement from Lattice Semiconductor Corporation. |
| philpem@0 | 7 | // The entire notice above must be reproduced on all authorized copies and |
| philpem@0 | 8 | // copies may only be made to the extent permitted by a licensing agreement from |
| philpem@0 | 9 | // Lattice Semiconductor Corporation. |
| philpem@0 | 10 | // |
| philpem@0 | 11 | // Lattice Semiconductor Corporation TEL : 1-800-Lattice (USA and Canada) |
| philpem@0 | 12 | // 5555 NE Moore Court 408-826-6000 (other locations) |
| philpem@0 | 13 | // Hillsboro, OR 97124 web : http://www.latticesemi.com/ |
| philpem@0 | 14 | // U.S.A email: techsupport@latticesemi.com |
| philpem@0 | 15 | // ============================================================================/ |
| philpem@0 | 16 | // FILE DETAILS |
| philpem@0 | 17 | // Project : LatticeMico32 |
| philpem@0 | 18 | // File : lm32_adder.v |
| philpem@0 | 19 | // Title : Integer adder / subtractor with comparison flag generation |
| philpem@0 | 20 | // Dependencies : lm32_include.v |
| philpem@0 | 21 | // Version : 6.1.17 |
| philpem@0 | 22 | // : Initial Release |
| philpem@0 | 23 | // Version : 7.0SP2, 3.0 |
| philpem@0 | 24 | // : No Change |
| philpem@0 | 25 | // Version : 3.1 |
| philpem@0 | 26 | // : No Change |
| philpem@0 | 27 | // ============================================================================= |
| philpem@0 | 28 | |
| philpem@0 | 29 | `include "lm32_include.v" |
| philpem@0 | 30 | |
| philpem@0 | 31 | ///////////////////////////////////////////////////// |
| philpem@0 | 32 | // Module interface |
| philpem@0 | 33 | ///////////////////////////////////////////////////// |
| philpem@0 | 34 | |
| philpem@0 | 35 | module lm32_adder ( |
| philpem@0 | 36 | // ----- Inputs ------- |
| philpem@0 | 37 | adder_op_x, |
| philpem@0 | 38 | adder_op_x_n, |
| philpem@0 | 39 | operand_0_x, |
| philpem@0 | 40 | operand_1_x, |
| philpem@0 | 41 | // ----- Outputs ------- |
| philpem@0 | 42 | adder_result_x, |
| philpem@0 | 43 | adder_carry_n_x, |
| philpem@0 | 44 | adder_overflow_x |
| philpem@0 | 45 | ); |
| philpem@0 | 46 | |
| philpem@0 | 47 | ///////////////////////////////////////////////////// |
| philpem@0 | 48 | // Inputs |
| philpem@0 | 49 | ///////////////////////////////////////////////////// |
| philpem@0 | 50 | |
| philpem@0 | 51 | input adder_op_x; // Operating to perform, 0 for addition, 1 for subtraction |
| philpem@0 | 52 | input adder_op_x_n; // Inverted version of adder_op_x |
| philpem@0 | 53 | input [`LM32_WORD_RNG] operand_0_x; // Operand to add, or subtract from |
| philpem@0 | 54 | input [`LM32_WORD_RNG] operand_1_x; // Opearnd to add, or subtract by |
| philpem@0 | 55 | |
| philpem@0 | 56 | ///////////////////////////////////////////////////// |
| philpem@0 | 57 | // Outputs |
| philpem@0 | 58 | ///////////////////////////////////////////////////// |
| philpem@0 | 59 | |
| philpem@0 | 60 | output [`LM32_WORD_RNG] adder_result_x; // Result of addition or subtraction |
| philpem@0 | 61 | wire [`LM32_WORD_RNG] adder_result_x; |
| philpem@0 | 62 | output adder_carry_n_x; // Inverted carry |
| philpem@0 | 63 | wire adder_carry_n_x; |
| philpem@0 | 64 | output adder_overflow_x; // Indicates if overflow occured, only valid for subtractions |
| philpem@0 | 65 | reg adder_overflow_x; |
| philpem@0 | 66 | |
| philpem@0 | 67 | ///////////////////////////////////////////////////// |
| philpem@0 | 68 | // Internal nets and registers |
| philpem@0 | 69 | ///////////////////////////////////////////////////// |
| philpem@0 | 70 | |
| philpem@0 | 71 | wire a_sign; // Sign (i.e. positive or negative) of operand 0 |
| philpem@0 | 72 | wire b_sign; // Sign of operand 1 |
| philpem@0 | 73 | wire result_sign; // Sign of result |
| philpem@0 | 74 | |
| philpem@0 | 75 | ///////////////////////////////////////////////////// |
| philpem@0 | 76 | // Instantiations |
| philpem@0 | 77 | ///////////////////////////////////////////////////// |
| philpem@0 | 78 | |
| philpem@0 | 79 | lm32_addsub addsub ( |
| philpem@0 | 80 | // ----- Inputs ----- |
| philpem@0 | 81 | .DataA (operand_0_x), |
| philpem@0 | 82 | .DataB (operand_1_x), |
| philpem@0 | 83 | .Cin (adder_op_x), |
| philpem@0 | 84 | .Add_Sub (adder_op_x_n), |
| philpem@0 | 85 | // ----- Ouputs ----- |
| philpem@0 | 86 | .Result (adder_result_x), |
| philpem@0 | 87 | .Cout (adder_carry_n_x) |
| philpem@0 | 88 | ); |
| philpem@0 | 89 | |
| philpem@0 | 90 | ///////////////////////////////////////////////////// |
| philpem@0 | 91 | // Combinational Logic |
| philpem@0 | 92 | ///////////////////////////////////////////////////// |
| philpem@0 | 93 | |
| philpem@0 | 94 | // Extract signs of operands and result |
| philpem@0 | 95 | |
| philpem@0 | 96 | assign a_sign = operand_0_x[`LM32_WORD_WIDTH-1]; |
| philpem@0 | 97 | assign b_sign = operand_1_x[`LM32_WORD_WIDTH-1]; |
| philpem@0 | 98 | assign result_sign = adder_result_x[`LM32_WORD_WIDTH-1]; |
| philpem@0 | 99 | |
| philpem@0 | 100 | // Determine whether an overflow occured when performing a subtraction |
| philpem@0 | 101 | |
| philpem@0 | 102 | always @(*) |
| philpem@0 | 103 | begin |
| philpem@0 | 104 | // +ve - -ve = -ve -> overflow |
| philpem@0 | 105 | // -ve - +ve = +ve -> overflow |
| philpem@0 | 106 | if ( (!a_sign & b_sign & result_sign) |
| philpem@0 | 107 | || (a_sign & !b_sign & !result_sign) |
| philpem@0 | 108 | ) |
| philpem@0 | 109 | adder_overflow_x = `TRUE; |
| philpem@0 | 110 | else |
| philpem@0 | 111 | adder_overflow_x = `FALSE; |
| philpem@0 | 112 | end |
| philpem@0 | 113 | |
| philpem@0 | 114 | endmodule |
| philpem@0 | 115 |