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csr cleanup

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This commit is contained in:
David Harris 2023-01-13 21:00:06 -08:00
parent 7358402bc0
commit e4f4b31896
1 changed files with 26 additions and 36 deletions
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20
pipelined/src/privileged/csr.sv
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@ -129,16 +129,8 @@ module csr #(parameter
endcase endcase
/////////////////////////////////////////// ///////////////////////////////////////////
// Trap Vectoring & Returns // Trap Vectoring & Returns; vectored traps must be aligned to 64-byte address boundaries
/////////////////////////////////////////// ///////////////////////////////////////////
//
// POSSIBLE OPTIMIZATION:
// From 20190608 privielegd spec page 27 (3.1.7)
// > Allowing coarser alignments in Vectored mode enables vectoring to be
// > implemented without a hardware adder circuit.
// For example, we could require m/stvec be aligned on 7 bits to let us replace the adder directly below with
// [untested] TrapVectorM = {TVec[`XLEN-1:7], CauseM[3:0], 4'b0000}
// However, this is program dependent, so not implemented at this time.
// Select trap vector from STVEC or MTVEC and word-align // Select trap vector from STVEC or MTVEC and word-align
assign SelMtvecM = (NextPrivilegeModeM == `M_MODE); assign SelMtvecM = (NextPrivilegeModeM == `M_MODE);
@ -150,10 +142,7 @@ module csr #(parameter
logic VectoredM; logic VectoredM;
logic [`XLEN-1:0] TVecPlusCauseM; logic [`XLEN-1:0] TVecPlusCauseM;
assign VectoredM = InterruptM & (TVecM[1:0] == 2'b01); assign VectoredM = InterruptM & (TVecM[1:0] == 2'b01);
// *** Would like you use concat version, but breaks uart test wally64priv when assign TVecPlusCauseM = {TVecAlignedM[`XLEN-1:6], CauseM[3:0], 2'b00}; // 64-byte alignment allows concatenation rather than addition
// mtvec is aligned to 64 bytes.
assign TVecPlusCauseM = TVecAlignedM + {{(`XLEN-2-`LOG_XLEN){1'b0}}, CauseM, 2'b00};
//assign TVecPlusCauseM = {TVecAlignedM[`XLEN-1:6], CauseM[3:0], 2'b00};
mux2 #(`XLEN) trapvecmux(TVecAlignedM, TVecPlusCauseM, VectoredM, TrapVectorM); mux2 #(`XLEN) trapvecmux(TVecAlignedM, TVecPlusCauseM, VectoredM, TrapVectorM);
end else end else
assign TrapVectorM = TVecAlignedM; assign TrapVectorM = TVecAlignedM;
@ -168,6 +157,7 @@ module csr #(parameter
/////////////////////////////////////////// ///////////////////////////////////////////
// CSRWriteValM // CSRWriteValM
/////////////////////////////////////////// ///////////////////////////////////////////
always_comb begin always_comb begin
// Choose either rs1 or uimm[4:0] as source // Choose either rs1 or uimm[4:0] as source
CSRSrcM = InstrM[14] ? {{(`XLEN-5){1'b0}}, InstrM[19:15]} : SrcAM; CSRSrcM = InstrM[14] ? {{(`XLEN-5){1'b0}}, InstrM[19:15]} : SrcAM;
@ -191,6 +181,7 @@ module csr #(parameter
/////////////////////////////////////////// ///////////////////////////////////////////
// CSR Write values // CSR Write values
/////////////////////////////////////////// ///////////////////////////////////////////
assign CSRAdrM = InstrM[31:20]; assign CSRAdrM = InstrM[31:20];
assign UnalignedNextEPCM = TrapM ? ((wfiM & IntPendingM) ? PCM+4 : PCM) : CSRWriteValM; assign UnalignedNextEPCM = TrapM ? ((wfiM & IntPendingM) ? PCM+4 : PCM) : CSRWriteValM;
assign NextEPCM = `C_SUPPORTED ? {UnalignedNextEPCM[`XLEN-1:1], 1'b0} : {UnalignedNextEPCM[`XLEN-1:2], 2'b00}; // 3.1.15 alignment assign NextEPCM = `C_SUPPORTED ? {UnalignedNextEPCM[`XLEN-1:1], 1'b0} : {UnalignedNextEPCM[`XLEN-1:2], 2'b00}; // 3.1.15 alignment
@ -218,8 +209,7 @@ module csr #(parameter
.STATUS_MPP, .STATUS_SPP, .STATUS_TSR, .STATUS_TW, .STATUS_MPP, .STATUS_SPP, .STATUS_TSR, .STATUS_TW,
.STATUS_MIE, .STATUS_SIE, .STATUS_MXR, .STATUS_SUM, .STATUS_MPRV, .STATUS_TVM, .STATUS_MIE, .STATUS_SIE, .STATUS_MXR, .STATUS_SUM, .STATUS_MPRV, .STATUS_TVM,
.STATUS_FS, .BigEndianM); .STATUS_FS, .BigEndianM);
csrc counters(.clk, .reset, csrc counters(.clk, .reset, .StallE, .StallM, .FlushM,
.StallE, .StallM, .FlushM,
.InstrValidNotFlushedM, .LoadStallD, .CSRMWriteM, .InstrValidNotFlushedM, .LoadStallD, .CSRMWriteM,
.DirPredictionWrongM, .BTBPredPCWrongM, .RASPredPCWrongM, .PredictionInstrClassWrongM, .DirPredictionWrongM, .BTBPredPCWrongM, .RASPredPCWrongM, .PredictionInstrClassWrongM,
.InstrClassM, .DCacheMiss, .DCacheAccess, .ICacheMiss, .ICacheAccess, .InstrClassM, .DCacheMiss, .DCacheAccess, .ICacheMiss, .ICacheAccess,