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Refactored IEU/ALU logic

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This commit is contained in:
David Harris 2021-12-08 13:48:04 -08:00
parent e14eb9872e
commit a1f8f7babe
3 changed files with 5 additions and 11 deletions
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2
wally-pipelined/src/ieu/controller.sv
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@ -173,7 +173,7 @@ module controller(
assign subD = (Funct3D == 3'b000 & Funct7D[5] & OpD[5]);
assign sraD = (Funct3D == 3'b101 & Funct7D[5]);
assign SubArithD = subD | sraD | sltD | sltuD; // TRUE for R-type subtracts and sra, slt, sltu
assign SubArithD = ALUOpD & (subD | sraD | sltD | sltuD); // TRUE for R-type subtracts and sra, slt, sltu
// assign SubArithD = aluc3D; // ***cleanup
// *** replace all of this

7
wally-pipelined/src/ieu/datapath.sv
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@ -111,14 +111,9 @@ module datapath (
mux3 #(`XLEN) fbemux(RD2E, WriteDataW, ResultM, ForwardBE, ForwardedSrcBE);
mux2 #(`XLEN) writedatamux(ForwardedSrcBE, FWriteDataE, ~IllegalFPUInstrE, WriteDataE);
mux2 #(`XLEN) srcamux(ForwardedSrcAE, PCE, ALUSrcAE, SrcAE);
// mux2 #(`XLEN) srcamux2(SrcAE, PCLinkE, JumpE, SrcAE2);
mux2 #(`XLEN) srcbmux(ForwardedSrcBE, ExtImmE, ALUSrcBE, SrcBE);
// mux2 #(`XLEN) srcbmux2(SrcBE, {`XLEN{1'b0}}, JumpE, SrcBE2); // *** May be able to remove this mux.
alu #(`XLEN) alu(SrcAE/*SrcAE2*/, SrcBE/*SrcBE2*/, ALUControlE, Funct3E, ALUPreResultE, AddressE /*, FlagsE */);
// redo ALUControlE to simplify - jus needs ALUAddE, Funct3E, W64E
alu #(`XLEN) alu(SrcAE, SrcBE, ALUControlE, Funct3E, ALUPreResultE, AddressE);
comparator #(`XLEN) comp(ForwardedSrcAE, ForwardedSrcBE, FlagsE);
// mux2 #(`XLEN) targetsrcmux(PCE, SrcAE, TargetSrcE, TargetBaseE); // *** PCE alsready should be selectable for SrcAE
// assign PCTargetE = ExtImmE + TargetBaseE;
mux2 #(`XLEN) altresultmux(ExtImmE, PCLinkE, JumpE, AltResultE);
mux2 #(`XLEN) aluresultmux(ALUPreResultE, AltResultE, ALUResultSrcE, ALUResultE);

7
wally-pipelined/src/ieu/ieu.sv
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@ -99,7 +99,7 @@ module ieu (
.StallE, .FlushE, .FlagsE,
.PCSrcE, // for datapath and Hazard Unit
.ALUControlE, .ALUSrcAE, .ALUSrcBE,
.TargetSrcE,
.ALUResultSrcE,
.MemReadE, .CSRReadE, // for Hazard Unit
.Funct3E, .MulDivE, .W64E,
.JumpE,
@ -124,12 +124,11 @@ module ieu (
.ImmSrcD, .InstrD,
// Execute stage signals
.StallE, .FlushE, .ForwardAE, .ForwardBE,
.ALUControlE, .ALUSrcAE, .ALUSrcBE,
.TargetSrcE, .JumpE, .IllegalFPUInstrE,
.ALUControlE, .Funct3E, .ALUSrcAE, .ALUSrcBE,
.ALUResultSrcE, .JumpE, .IllegalFPUInstrE,
.FWriteDataE, .PCE, .PCLinkE, .FlagsE,
.PCTargetE,
.ForwardedSrcAE, .ForwardedSrcBE, // *** these are the src outputs before the mux choosing between them and PCE to put in srcA/B
.SrcAE, .SrcBE,
// Memory stage signals
.StallM, .FlushM, .FWriteIntM, .FIntResM,
.SrcAM, .WriteDataM, .MemAdrM, .MemAdrE,