diff options
Diffstat (limited to 'decoder.v')
| -rw-r--r-- | decoder.v | 38 |
1 files changed, 19 insertions, 19 deletions
@@ -18,7 +18,7 @@ module decoder ( output memWriteB, output memWriteW, - output [4:0] setRegCond, // {should set when condition is true, Z doesn't matter, S doesn't matter, Z must be this, S must be this} + output [5:0] setRegCond, // {should set when condition is true, Z condition, combiner, C condition}, condition = (00: must be 0, 01: must be 1, 1x: don't care) output [15:0] imm ); @@ -111,14 +111,14 @@ module decoder ( // b** // 0110 + [which] + 0 + [immediate offset] -// which: 000 eq (Z = 1, S = x) -// 001 ne (Z = 0, S = x) -// 010 gt (Z = 0, S = 0) -// 011 ge (Z = x, S = 0) -// 100 lt (Z = 0, S = 1) -// 101 le (Z = x, S = 1) +// which: 000 eq (Z = 1 and C = 0) +// 001 ne (Z = 0 and C = x) +// 010 gt (Z = 0 and C = 0) +// 011 ge (Z = 1 or C = 0) +// 100 lt (Z = 0 and C = 1) +// 101 le (Z = 1 or C = 1) // 110 ?? -// 111 always (Z = x, S = x) +// 111 always (Z = x, C = x) // jmp // 0111 + 00000 + [reg1] + 00000 @@ -172,14 +172,14 @@ module decoder ( // for instr_branch wire [2:0] branch_cond = instr[11:9]; wire [7:0] branch_offset = instr[7:0]; - wire [4:0] branch_set_cond = - branch_cond == 3'h0 ? 5'b10110 : // EQ - branch_cond == 3'h1 ? 5'b10100 : // NE - branch_cond == 3'h2 ? 5'b10000 : // GT - branch_cond == 3'h3 ? 5'b11000 : // GE - branch_cond == 3'h4 ? 5'b10001 : // LT - branch_cond == 3'h5 ? 5'b11001 : // LE - 5'b11100; + wire [5:0] branch_set_cond = + branch_cond == 3'h0 ? 6'b1_01_1_00 : // EQ + branch_cond == 3'h1 ? 6'b1_00_1_10 : // NE + branch_cond == 3'h2 ? 6'b1_00_1_00 : // GT + branch_cond == 3'h3 ? 6'b1_01_0_00 : // GE + branch_cond == 3'h4 ? 6'b1_00_1_01 : // LT + branch_cond == 3'h5 ? 6'b1_01_0_01 : // LE + 6'b1_10_0_10; assign aluOp = instr_math ? {1'b0, math_op} : @@ -228,10 +228,10 @@ module decoder ( assign memWriteW = instr_mov ? (mov_mem & (!mov_mem_read & mov_word)) : 1'b0; assign setRegCond = - instr_mov ? ((!mov_mem | mov_mem_read) ? 5'b11100 : 5'b00000) : + instr_mov ? ((!mov_mem | mov_mem_read) ? 6'b1_10_0_10 : 6'b000000) : instr_branch ? branch_set_cond : - instr_nop ? 5'b00000 : - 5'b11100; + instr_nop ? 6'b000000 : + 6'b1_10_0_10; assign imm = instr_notneg ? {15'b0, notneg_is_neg} : |