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Replace div/rem expressions with divider modules in preparation for pipelining

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wgulian3
2020-02-04 11:54:06 -05:00
parent 0211ca4add
commit 9c7a9d88cf
1 changed files with 50 additions and 17 deletions
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67
rtl/VX_alu.v
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@@ -20,8 +20,10 @@ module VX_alu(
wire[63:0] ALU_in1_mult;
wire[63:0] ALU_in2_mult;
wire[31:0] upper_immed;
wire[31:0] div_result;
wire[31:0] rem_result;
wire[31:0] unsigned_div_result;
wire[31:0] unsigned_rem_result;
wire[31:0] signed_div_result;
wire[31:0] signed_rem_result;
assign which_in2 = in_rs2_src == `RS2_IMMED;
@@ -33,6 +35,37 @@ module VX_alu(
assign upper_immed = {in_upper_immed, {12{1'b0}}};
VX_divide #(
.WIDTHN(32),
.WIDTHD(32),
.SPEED("HIGHEST"),
.PIPELINE(0)
) unsigned_div (
.clk(0),
.aclr(0),
.clken(1), // TODO this could be disabled on inactive instructions
.numer(ALU_in1),
.denom(ALU_in2),
.quotient(unsigned_div_result),
.remainder(unsigned_rem_result)
);
VX_divide #(
.WIDTHN(32),
.WIDTHD(32),
.NREP("SIGNED"),
.DREP("SIGNED"),
.SPEED("HIGHEST"),
.PIPELINE(0)
) signed_div (
.clk(0),
.aclr(0),
.clken(1), // TODO this could be disabled on inactive instructions
.numer(ALU_in1),
.denom(ALU_in2),
.quotient(signed_div_result),
.remainder(signed_rem_result)
);
//always @(posedge `MUL) begin
@@ -42,7 +75,7 @@ module VX_alu(
wire[63:0] alu_in1_signed = {{32{ALU_in1[31]}}, ALU_in1};
wire[63:0] alu_in2_signed = {{32{ALU_in2[31]}}, ALU_in2};
wire[63:0] alu_in2_signed = {{32{ALU_in2[31]}}, ALU_in2};
assign ALU_in1_mult = (in_alu_op == `MULHU || in_alu_op == `DIVU || in_alu_op == `REMU) ? {32'b0, ALU_in1} : alu_in1_signed;
assign ALU_in2_mult = (in_alu_op == `MULHU || in_alu_op == `MULHSU || in_alu_op == `DIVU || in_alu_op == `REMU) ? {32'b0, ALU_in2} : alu_in2_signed;
wire[63:0] mult_result = ALU_in1_mult * ALU_in2_mult;
@@ -57,26 +90,26 @@ module VX_alu(
`SLT: out_alu_result = ($signed(ALU_in1) < $signed(ALU_in2)) ? 32'h1 : 32'h0;
`SLTU: out_alu_result = ALU_in1 < ALU_in2 ? 32'h1 : 32'h0;
`XOR: out_alu_result = ALU_in1 ^ ALU_in2;
`SRL: out_alu_result = ALU_in1 >> ALU_in2[4:0];
`SRL: out_alu_result = ALU_in1 >> ALU_in2[4:0];
`SRA: out_alu_result = $signed(ALU_in1) >>> ALU_in2[4:0];
`OR: out_alu_result = ALU_in1 | ALU_in2;
`AND: out_alu_result = ALU_in2 & ALU_in1;
`OR: out_alu_result = ALU_in1 | ALU_in2;
`AND: out_alu_result = ALU_in2 & ALU_in1;
`SUBU: out_alu_result = (ALU_in1 >= ALU_in2) ? 32'h0 : 32'hffffffff;
`LUI_ALU: out_alu_result = upper_immed;
`AUIPC_ALU: out_alu_result = $signed(in_curr_PC) + $signed(upper_immed);
`MUL: out_alu_result = mult_result[31:0];
`MUL: out_alu_result = mult_result[31:0];
`MULH: out_alu_result = mult_result[63:32];
`MULHSU: out_alu_result = mult_result[63:32];
`MULHU: out_alu_result = mult_result[63:32];
`DIV: out_alu_result = (ALU_in2 == 0) ? 32'hffffffff : $signed($signed(ALU_in1) / $signed(ALU_in2));
`DIVU: out_alu_result = (ALU_in2 == 0) ? 32'hffffffff : ALU_in1 / ALU_in2;
`REM: out_alu_result = (ALU_in2 == 0) ? ALU_in1 : $signed($signed(ALU_in1) % $signed(ALU_in2));
`REMU: out_alu_result = (ALU_in2 == 0) ? ALU_in1 : ALU_in1 % ALU_in2;
`DIV: out_alu_result = (ALU_in2 == 0) ? 32'hffffffff : signed_div_result;
`DIVU: out_alu_result = (ALU_in2 == 0) ? 32'hffffffff : unsigned_div_result;
`REM: out_alu_result = (ALU_in2 == 0) ? ALU_in1 : signed_rem_result;
`REMU: out_alu_result = (ALU_in2 == 0) ? ALU_in1 : unsigned_rem_result;
default: out_alu_result = 32'h0;
endcase // in_alu_op
end
`else
`else
wire which_in2;
wire[31:0] ALU_in1;
@@ -116,10 +149,10 @@ module VX_alu(
`SLT: out_alu_result = ($signed(ALU_in1) < $signed(ALU_in2)) ? 32'h1 : 32'h0;
`SLTU: out_alu_result = ALU_in1 < ALU_in2 ? 32'h1 : 32'h0;
`XOR: out_alu_result = ALU_in1 ^ ALU_in2;
`SRL: out_alu_result = ALU_in1 >> ALU_in2[4:0];
`SRL: out_alu_result = ALU_in1 >> ALU_in2[4:0];
`SRA: out_alu_result = $signed(ALU_in1) >>> ALU_in2[4:0];
`OR: out_alu_result = ALU_in1 | ALU_in2;
`AND: out_alu_result = ALU_in2 & ALU_in1;
`OR: out_alu_result = ALU_in1 | ALU_in2;
`AND: out_alu_result = ALU_in2 & ALU_in1;
`SUBU: out_alu_result = (ALU_in1 >= ALU_in2) ? 32'h0 : 32'hffffffff;
`LUI_ALU: out_alu_result = upper_immed;
`AUIPC_ALU: out_alu_result = $signed(in_curr_PC) + $signed(upper_immed);
@@ -133,7 +166,7 @@ module VX_alu(
`REMU: out_alu_result = (ALU_in2 == 0) ? ALU_in1 : ALU_in1 % ALU_in2;
default: out_alu_result = 32'h0;
endcase // in_alu_op
end
end
`endif
endmodule // VX_alu
endmodule