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Use one-hot encoding for ALU rd sel

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Olof Kindgren
2019-12-07 23:36:36 +01:00
parent eb5d25ea1c
commit 6067b0e684
4 changed files with 11 additions and 25 deletions
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16
rtl/serv_decode.v
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@@ -33,7 +33,7 @@ module serv_decode
output wire o_alu_cmp_uns,
output wire o_alu_sh_signed,
output wire o_alu_sh_right,
output reg [1:0] o_alu_rd_sel,
output wire [3:0] o_alu_rd_sel,
//To RF
output wire o_rf_rd_en,
output reg [4:0] o_rf_rd_addr,
@@ -175,16 +175,10 @@ module serv_decode
reg [4:0] imm24_20;
reg [4:0] imm11_7;
always @(funct3)
casez(funct3)
3'b000 : o_alu_rd_sel = ALU_RESULT_ADD;
3'b001 : o_alu_rd_sel = ALU_RESULT_SR;
3'b01? : o_alu_rd_sel = ALU_RESULT_LT;
3'b100 : o_alu_rd_sel = ALU_RESULT_BOOL;
3'b101 : o_alu_rd_sel = ALU_RESULT_SR;
3'b11? : o_alu_rd_sel = ALU_RESULT_BOOL;
endcase
assign o_alu_rd_sel[0] = (funct3 == 3'b000); // Add/sub
assign o_alu_rd_sel[1] = (funct3[1:0] == 2'b01); //Shift
assign o_alu_rd_sel[2] = (funct3[2:1] == 2'b01); //SLT*
assign o_alu_rd_sel[3] = (funct3[2] & !(funct3[1:0] == 2'b01)); //Bool
always @(posedge clk) begin
if (i_wb_en) begin
o_rf_rd_addr <= i_wb_rdt[11:7];