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Forgot to include a few files in the last few commits.

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Also reorganized the dcache by read cpu path, write cpu path, and bus interface path.
Changed i/o names on subwordread to match signals in dcache.
This commit is contained in:
Ross Thompson 2021-08-25 22:30:05 -05:00
parent 0530047f53
commit 596bc138bc
4 changed files with 968 additions and 188 deletions
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46
wally-pipelined/src/cache/cacheLRU.sv → wally-pipelined/src/cache/cachereplacementpolicy.sv vendored
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@ -24,13 +24,13 @@
`include "wally-config.vh"
module cacheLRU
module cachereplacementpolicy
#(NUMWAYS, INDEXLEN, OFFSETLEN, NUMLINES)
(input logic clk, reset,
input logic [NUMWAYS-1:0] WayIn,
input logic [NUMWAYS-1:0] WayHit,
output logic [NUMWAYS-1:0] VictimWay,
input logic [INDEXLEN+OFFSETLEN-1:OFFSETLEN] MemPAdrM,
input logic [INDEXLEN-1:0] SRAMAdr,
input logic [INDEXLEN-1:0] RAdr,
input logic LRUWriteEn
);
@ -48,7 +48,7 @@ module cacheLRU
for(int index = 0; index < NUMLINES; index++)
ReplacementBits[index] <= '0;
end else begin
BlockReplacementBits <= ReplacementBits[SRAMAdr];
BlockReplacementBits <= ReplacementBits[RAdr];
if (LRUWriteEn) begin
ReplacementBits[MemPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]] <= NewReplacement;
end
@ -62,7 +62,7 @@ module cacheLRU
assign LRUEn[0] = 1'b0;
assign NewReplacement[0] = WayIn[1];
assign NewReplacement[0] = WayHit[1];
assign VictimWay[1] = ~BlockReplacementBits[0];
assign VictimWay[0] = BlockReplacementBits[0];
@ -71,13 +71,13 @@ module cacheLRU
// selects
assign LRUEn[2] = 1'b1;
assign LRUEn[1] = WayIn[3];
assign LRUEn[0] = WayIn[3] | WayIn[2];
assign LRUEn[1] = WayHit[3];
assign LRUEn[0] = WayHit[3] | WayHit[2];
// mask
assign LRUMask[0] = WayIn[1];
assign LRUMask[1] = WayIn[3];
assign LRUMask[2] = WayIn[3] | WayIn[2];
assign LRUMask[0] = WayHit[1];
assign LRUMask[1] = WayHit[3];
assign LRUMask[2] = WayHit[3] | WayHit[2];
for(index = 0; index < NUMWAYS-1; index++)
assign NewReplacement[index] = LRUEn[index] ? LRUMask[index] : BlockReplacementBits[index];
@ -93,21 +93,21 @@ module cacheLRU
// selects
assign LRUEn[6] = 1'b1;
assign LRUEn[5] = WayIn[7] | WayIn[6] | WayIn[5] | WayIn[4];
assign LRUEn[4] = WayIn[7] | WayIn[6];
assign LRUEn[3] = WayIn[5] | WayIn[4];
assign LRUEn[2] = WayIn[3] | WayIn[2] | WayIn[1] | WayIn[0];
assign LRUEn[1] = WayIn[3] | WayIn[2];
assign LRUEn[0] = WayIn[1] | WayIn[0];
assign LRUEn[5] = WayHit[7] | WayHit[6] | WayHit[5] | WayHit[4];
assign LRUEn[4] = WayHit[7] | WayHit[6];
assign LRUEn[3] = WayHit[5] | WayHit[4];
assign LRUEn[2] = WayHit[3] | WayHit[2] | WayHit[1] | WayHit[0];
assign LRUEn[1] = WayHit[3] | WayHit[2];
assign LRUEn[0] = WayHit[1] | WayHit[0];
// mask
assign LRUMask[6] = WayIn[7] | WayIn[6] | WayIn[5] | WayIn[4];
assign LRUMask[5] = WayIn[7] | WayIn[6];
assign LRUMask[4] = WayIn[7];
assign LRUMask[3] = WayIn[5];
assign LRUMask[2] = WayIn[3] | WayIn[2];
assign LRUMask[1] = WayIn[2];
assign LRUMask[0] = WayIn[0];
assign LRUMask[6] = WayHit[7] | WayHit[6] | WayHit[5] | WayHit[4];
assign LRUMask[5] = WayHit[7] | WayHit[6];
assign LRUMask[4] = WayHit[7];
assign LRUMask[3] = WayHit[5];
assign LRUMask[2] = WayHit[3] | WayHit[2];
assign LRUMask[1] = WayHit[2];
assign LRUMask[0] = WayHit[0];
for(index = 0; index < NUMWAYS-1; index++)
assign NewReplacement[index] = LRUEn[index] ? LRUMask[index] : BlockReplacementBits[index];

133
wally-pipelined/src/cache/dcache.sv vendored
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@ -90,7 +90,7 @@ module dcache
logic [1:0] SelAdrM;
logic [INDEXLEN-1:0] SRAMAdr;
logic [INDEXLEN-1:0] RAdr;
logic [BLOCKLEN-1:0] SRAMWriteData;
logic [BLOCKLEN-1:0] DCacheMemWriteData;
logic SetValid, ClearValid;
@ -135,84 +135,65 @@ module dcache
logic LRUWriteEn;
// data path
// Read Path CPU (IEU) side
mux3 #(INDEXLEN)
AdrSelMux(.d0(MemAdrE[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d1(MemPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d2(VAdr[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d1(VAdr[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.d2(MemPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.s(SelAdrM),
.y(SRAMAdr));
.y(RAdr));
onehotdecoder #(LOGWPL)
adrdec(.bin(MemPAdrM[LOGWPL+LOGXLENBYTES-1:LOGXLENBYTES]),
.decoded(MemPAdrDecodedW));
assign SRAMWordEnable = SRAMBlockWriteEnableM ? '1 : MemPAdrDecodedW;
cacheway #(.NUMLINES(NUMLINES), .BLOCKLEN(BLOCKLEN), .TAGLEN(TAGLEN), .OFFSETLEN(OFFSETLEN), .INDEXLEN(INDEXLEN))
MemWay[NUMWAYS-1:0](.clk,
.reset,
.RAdr(SRAMAdr),
.MemPAdrM(MemPAdrM[`PA_BITS-1:0]),
.WriteEnable(SRAMWayWriteEnable),
.WriteWordEnable(SRAMWordEnable),
.TagWriteEnable(SRAMBlockWayWriteEnableM),
.WriteData(SRAMWriteData),
.SetValid,
.ClearValid,
.SetDirty,
.ClearDirty,
.SelEvict,
.VictimWay,
.ReadDataBlockWayMaskedM,
.WayHit,
.VictimDirtyWay,
.VictimTagWay);
.reset,
.RAdr,
.MemPAdrM(MemPAdrM[`PA_BITS-1:0]),
.WriteEnable(SRAMWayWriteEnable),
.WriteWordEnable(SRAMWordEnable),
.TagWriteEnable(SRAMBlockWayWriteEnableM),
.WriteData(SRAMWriteData),
.SetValid,
.ClearValid,
.SetDirty,
.ClearDirty,
.SelEvict,
.VictimWay,
.ReadDataBlockWayMaskedM,
.WayHit,
.VictimDirtyWay,
.VictimTagWay);
generate
if(NUMWAYS > 1) begin
cacheLRU #(NUMWAYS, INDEXLEN, OFFSETLEN, NUMLINES)
cacheLRU(.clk, .reset,
.WayIn(WayHit),
.VictimWay,
.MemPAdrM(MemPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.SRAMAdr,
.LRUWriteEn);
cachereplacementpolicy #(NUMWAYS, INDEXLEN, OFFSETLEN, NUMLINES)
cachereplacementpolicy(.clk, .reset,
.WayHit,
.VictimWay,
.MemPAdrM(MemPAdrM[INDEXLEN+OFFSETLEN-1:OFFSETLEN]),
.RAdr,
.LRUWriteEn);
end else begin
assign VictimWay = 1'b1;
assign VictimWay = 1'b1; // one hot.
end
endgenerate
assign SRAMBlockWayWriteEnableM = SRAMBlockWriteEnableM ? VictimWay : '0;
mux2 #(NUMWAYS) WriteEnableMux(.d0(SRAMWordWriteEnableM ? WayHit : '0),
.d1(SRAMBlockWayWriteEnableM),
.s(SRAMBlockWriteEnableM),
.y(SRAMWayWriteEnable));
assign CacheHit = | WayHit;
assign VictimDirty = | VictimDirtyWay;
assign CacheHit = |WayHit;
// ReadDataBlockWayMaskedM is a 2d array of cache block len by number of ways.
// Need to OR together each way in a bitwise manner.
// Final part of the AO Mux.
// Final part of the AO Mux. First is the AND in the cacheway.
or_rows #(NUMWAYS, BLOCKLEN) ReadDataAOMux(.a(ReadDataBlockWayMaskedM), .y(ReadDataBlockM));
or_rows #(NUMWAYS, TAGLEN) VictimTagAOMux(.a(VictimTagWay), .y(VictimTag));
assign VictimDirty = | VictimDirtyWay;
// Convert the Read data bus ReadDataSelectWay into sets of XLEN so we can
// easily build a variable input mux.
// *** consider using a limited range shift to do this final muxing.
genvar index;
generate
for (index = 0; index < WORDSPERLINE; index++) begin
assign ReadDataBlockSetsM[index] = ReadDataBlockM[((index+1)*`XLEN)-1: (index*`XLEN)];
@ -222,20 +203,31 @@ module dcache
// variable input mux
assign ReadDataWordM = ReadDataBlockSetsM[MemPAdrM[$clog2(WORDSPERLINE+`XLEN/8) : $clog2(`XLEN/8)]];
assign HWDATA = CacheableM ? ReadDataBlockSetsM[FetchCount] : WriteDataM;
mux2 #(`XLEN) UnCachedDataMux(.d0(ReadDataWordM),
.d1(DCacheMemWriteData[`XLEN-1:0]),
.s(SelUncached),
.y(ReadDataWordMuxM));
// finally swr
// *** BUG fix HSIZED? why was it this way?
subwordread subwordread(.HRDATA(ReadDataWordMuxM),
.HADDRD(MemPAdrM[2:0]),
.HSIZED({Funct3M[2], 1'b0, Funct3M[1:0]}),
.HRDATAMasked(ReadDataM));
subwordread subwordread(.ReadDataWordMuxM,
.MemPAdrM(MemPAdrM[2:0]),
.Funct3M,
.ReadDataM);
// Write Path CPU (IEU) side
onehotdecoder #(LOGWPL)
adrdec(.bin(MemPAdrM[LOGWPL+LOGXLENBYTES-1:LOGXLENBYTES]),
.decoded(MemPAdrDecodedW));
assign SRAMWordEnable = SRAMBlockWriteEnableM ? '1 : MemPAdrDecodedW;
assign SRAMBlockWayWriteEnableM = SRAMBlockWriteEnableM ? VictimWay : '0;
mux2 #(NUMWAYS) WriteEnableMux(.d0(SRAMWordWriteEnableM ? WayHit : '0),
.d1(SRAMBlockWayWriteEnableM),
.s(SRAMBlockWriteEnableM),
.y(SRAMWayWriteEnable));
generate
if (`A_SUPPORTED) begin
@ -247,8 +239,6 @@ module dcache
assign FinalAMOWriteDataM = WriteDataM;
endgenerate
// write path
subwordwrite subwordwrite(.HRDATA(ReadDataWordM),
.HADDRD(MemPAdrM[2:0]),
.HSIZED({Funct3M[2], 1'b0, Funct3M[1:0]}),
@ -256,7 +246,15 @@ module dcache
.HWDATA(FinalWriteDataM));
mux2 #(BLOCKLEN) WriteDataMux(.d0({WORDSPERLINE{FinalWriteDataM}}),
.d1(DCacheMemWriteData),
.s(SRAMBlockWriteEnableM),
.y(SRAMWriteData));
// Bus Side logic
// register the fetch data from the next level of memory.
// This register should be necessary for timing. There is no register in the uncore or
// ahblite controller between the memories and this cache.
generate
for (index = 0; index < WORDSPERLINE; index++) begin:fetchbuffer
flopen #(`XLEN) fb(.clk(clk),
@ -278,13 +276,7 @@ module dcache
assign AHBPAdr = ({{`PA_BITS-LOGWPL{1'b0}}, FetchCount} << $clog2(`XLEN/8)) + BasePAdrMaskedM;
mux2 #(BLOCKLEN) WriteDataMux(.d0({WORDSPERLINE{FinalWriteDataM}}),
.d1(DCacheMemWriteData),
.s(SRAMBlockWriteEnableM),
.y(SRAMWriteData));
assign HWDATA = CacheableM ? ReadDataBlockSetsM[FetchCount] : WriteDataM;
localparam FetchCountThreshold = WORDSPERLINE - 1;
@ -302,9 +294,8 @@ module dcache
assign SRAMWriteEnable = SRAMBlockWriteEnableM | SRAMWordWriteEnableM;
// controller
// control path *** eventually move to own module.
dcachefsm dcachefsm(.clk,
.reset,
.MemRWM,

792
wally-pipelined/src/cache/dcachefsm.sv vendored Normal file
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@ -0,0 +1,792 @@
///////////////////////////////////////////
// dcache (data cache) fsm
//
// Written: ross1728@gmail.com August 25, 2021
// Implements the L1 data cache fsm
//
// Purpose: Controller for the dcache fsm
//
// A component of the Wally configurable RISC-V project.
//
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
///////////////////////////////////////////
`include "wally-config.vh"
module dcachefsm
(input logic clk,
input logic reset,
// inputs from IEU
input logic [1:0] MemRWM,
input logic [1:0] AtomicM,
// hazard inputs
input logic ExceptionM,
input logic PendingInterruptM,
input logic StallWtoDCache,
// mmu inputs
input logic DTLBMissM,
input logic ITLBMissF,
input logic CacheableM,
input logic DTLBWriteM,
input logic ITLBWriteF,
input logic WalkerInstrPageFaultF,
// hptw inputs
input logic SelPTW,
input logic WalkerPageFaultM,
// Bus inputs
input logic AHBAck, // from ahb
// dcache internals
input logic CacheHit,
input logic FetchCountFlag,
input logic VictimDirty,
// hazard outputs
output logic DCacheStall,
output logic CommittedM,
// counter outputs
output logic DCacheMiss,
output logic DCacheAccess,
// hptw outputs
output logic MemAfterIWalkDone,
// Bus outputs
output logic AHBRead,
output logic AHBWrite,
// dcache internals
output logic [1:0] SelAdrM,
output logic CntEn,
output logic SetValid,
output logic ClearValid,
output logic SetDirty,
output logic ClearDirty,
output logic SRAMWordWriteEnableM,
output logic SRAMBlockWriteEnableM,
output logic CntReset,
output logic SelUncached,
output logic SelEvict,
output logic LRUWriteEn
);
logic PreCntEn;
logic AnyCPUReqM;
typedef enum {STATE_READY,
STATE_MISS_FETCH_WDV,
STATE_MISS_FETCH_DONE,
STATE_MISS_EVICT_DIRTY,
STATE_MISS_WRITE_CACHE_BLOCK,
STATE_MISS_READ_WORD,
STATE_MISS_READ_WORD_DELAY,
STATE_MISS_WRITE_WORD,
STATE_PTW_READY,
STATE_PTW_READ_MISS_FETCH_WDV,
STATE_PTW_READ_MISS_FETCH_DONE,
STATE_PTW_READ_MISS_WRITE_CACHE_BLOCK,
STATE_PTW_READ_MISS_EVICT_DIRTY,
STATE_PTW_READ_MISS_READ_WORD,
STATE_PTW_READ_MISS_READ_WORD_DELAY,
STATE_PTW_ACCESS_AFTER_WALK,
STATE_UNCACHED_WRITE,
STATE_UNCACHED_WRITE_DONE,
STATE_UNCACHED_READ,
STATE_UNCACHED_READ_DONE,
STATE_PTW_FAULT_READY,
STATE_PTW_FAULT_CPU_BUSY,
STATE_PTW_FAULT_MISS_FETCH_WDV,
STATE_PTW_FAULT_MISS_FETCH_DONE,
STATE_PTW_FAULT_MISS_WRITE_CACHE_BLOCK,
STATE_PTW_FAULT_MISS_READ_WORD,
STATE_PTW_FAULT_MISS_READ_WORD_DELAY,
STATE_PTW_FAULT_MISS_WRITE_WORD,
STATE_PTW_FAULT_MISS_WRITE_WORD_DELAY,
STATE_PTW_FAULT_MISS_EVICT_DIRTY,
STATE_PTW_FAULT_UNCACHED_WRITE,
STATE_PTW_FAULT_UNCACHED_WRITE_DONE,
STATE_PTW_FAULT_UNCACHED_READ,
STATE_PTW_FAULT_UNCACHED_READ_DONE,
STATE_CPU_BUSY,
STATE_CPU_BUSY_FINISH_AMO} statetype;
statetype CurrState, NextState;
assign AnyCPUReqM = |MemRWM | (|AtomicM);
assign CntEn = PreCntEn & AHBAck;
always_ff @(posedge clk, posedge reset)
if (reset) CurrState <= #1 STATE_READY;
else CurrState <= #1 NextState;
// next state logic and some state ouputs.
always_comb begin
DCacheStall = 1'b0;
SelAdrM = 2'b00;
PreCntEn = 1'b0;
SetValid = 1'b0;
ClearValid = 1'b0;
SetDirty = 1'b0;
ClearDirty = 1'b0;
SRAMWordWriteEnableM = 1'b0;
SRAMBlockWriteEnableM = 1'b0;
CntReset = 1'b0;
AHBRead = 1'b0;
AHBWrite = 1'b0;
CommittedM = 1'b0;
SelUncached = 1'b0;
SelEvict = 1'b0;
DCacheAccess = 1'b0;
DCacheMiss = 1'b0;
LRUWriteEn = 1'b0;
MemAfterIWalkDone = 1'b0;
case (CurrState)
STATE_READY: begin
// TLB Miss
if((AnyCPUReqM & DTLBMissM) | ITLBMissF) begin
// the LSU arbiter has not yet selected the PTW.
// The CPU needs to be stalled until that happens.
// If we set DCacheStall for 1 cycle before going to
// PTW ready the CPU will stall.
// The page table walker asserts it's control 1 cycle
// after the TLBs miss.
CommittedM = 1'b1;
DCacheStall = 1'b1;
NextState = STATE_PTW_READY;
end
// amo hit
else if(AtomicM[1] & (&MemRWM) & CacheableM & ~(ExceptionM | PendingInterruptM) & CacheHit & ~DTLBMissM) begin
SelAdrM = 2'b10;
DCacheStall = 1'b0;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY_FINISH_AMO;
SelAdrM = 2'b10;
end
else begin
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
LRUWriteEn = 1'b1;
NextState = STATE_READY;
end
end
// read hit valid cached
else if(MemRWM[1] & CacheableM & ~(ExceptionM | PendingInterruptM) & CacheHit & ~DTLBMissM) begin
DCacheStall = 1'b0;
DCacheAccess = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
// write hit valid cached
else if (MemRWM[0] & CacheableM & ~(ExceptionM | PendingInterruptM) & CacheHit & ~DTLBMissM) begin
SelAdrM = 2'b10;
DCacheStall = 1'b0;
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
// read or write miss valid cached
else if((|MemRWM) & CacheableM & ~(ExceptionM | PendingInterruptM) & ~CacheHit & ~DTLBMissM) begin
NextState = STATE_MISS_FETCH_WDV;
CntReset = 1'b1;
DCacheStall = 1'b1;
DCacheAccess = 1'b1;
DCacheMiss = 1'b1;
end
// uncached write
else if(MemRWM[0] & ~CacheableM & ~(ExceptionM | PendingInterruptM) & ~DTLBMissM) begin
NextState = STATE_UNCACHED_WRITE;
CntReset = 1'b1;
DCacheStall = 1'b1;
AHBWrite = 1'b1;
end
// uncached read
else if(MemRWM[1] & ~CacheableM & ~(ExceptionM | PendingInterruptM) & ~DTLBMissM) begin
NextState = STATE_UNCACHED_READ;
CntReset = 1'b1;
DCacheStall = 1'b1;
AHBRead = 1'b1;
end
// fault
else if(AnyCPUReqM & (ExceptionM | PendingInterruptM) & ~DTLBMissM) begin
NextState = STATE_READY;
end
else NextState = STATE_READY;
end
STATE_MISS_FETCH_WDV: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBRead = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
if (FetchCountFlag & AHBAck) begin
NextState = STATE_MISS_FETCH_DONE;
end else begin
NextState = STATE_MISS_FETCH_WDV;
end
end
STATE_MISS_FETCH_DONE: begin
DCacheStall = 1'b1;
SelAdrM = 2'b10;
CntReset = 1'b1;
CommittedM = 1'b1;
if(VictimDirty) begin
NextState = STATE_MISS_EVICT_DIRTY;
end else begin
NextState = STATE_MISS_WRITE_CACHE_BLOCK;
end
end
STATE_MISS_WRITE_CACHE_BLOCK: begin
SRAMBlockWriteEnableM = 1'b1;
DCacheStall = 1'b1;
NextState = STATE_MISS_READ_WORD;
SelAdrM = 2'b10;
SetValid = 1'b1;
ClearDirty = 1'b1;
CommittedM = 1'b1;
//LRUWriteEn = 1'b1; // DO not update LRU on SRAM fetch update. Wait for subsequent read/write
end
STATE_MISS_READ_WORD: begin
SelAdrM = 2'b10;
DCacheStall = 1'b1;
CommittedM = 1'b1;
if (MemRWM[0]) begin // handles stores and amo write.
NextState = STATE_MISS_WRITE_WORD;
end else begin
NextState = STATE_MISS_READ_WORD_DELAY;
// delay state is required as the read signal MemRWM[1] is still high when we
// return to the ready state because the cache is stalling the cpu.
end
end
STATE_MISS_READ_WORD_DELAY: begin
//SelAdrM = 2'b10;
CommittedM = 1'b1;
if(&MemRWM & AtomicM[1]) begin // amo write
SelAdrM = 2'b10;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY_FINISH_AMO;
end
else begin
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
LRUWriteEn = 1'b1;
NextState = STATE_READY;
end
end else begin
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
end
STATE_MISS_WRITE_WORD: begin
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
STATE_MISS_EVICT_DIRTY: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBWrite = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
SelEvict = 1'b1;
if(FetchCountFlag & AHBAck) begin
NextState = STATE_MISS_WRITE_CACHE_BLOCK;
end else begin
NextState = STATE_MISS_EVICT_DIRTY;
end
end
STATE_PTW_READY: begin
// now all output connect to PTW instead of CPU.
CommittedM = 1'b1;
// In this branch we remove stall and go back to ready. There is no request for memory from the
// datapath or the walker had a fault.
// types 3b, 4a, 4b, and 7c.
if ((DTLBMissM & WalkerPageFaultM) | // 3b
(ITLBMissF & (WalkerInstrPageFaultF | ITLBWriteF) & ~AnyCPUReqM & ~DTLBMissM) | // 4a and 4b
(DTLBMissM & ITLBMissF & WalkerPageFaultM)) begin // 7c
NextState = STATE_READY;
DCacheStall = 1'b0;
end
// in this branch we go back to ready, but there is a memory operation from
// the datapath so we MUST stall and replay the operation.
// types 3a and 5a
else if ((DTLBMissM & DTLBWriteM) | // 3a
(ITLBMissF & ITLBWriteF & AnyCPUReqM)) begin // 5a
NextState = STATE_READY;
DCacheStall = 1'b1;
SelAdrM = 2'b01;
end
// like 5a we want to stall and go to the ready state, but we also have to save
// the WalkerInstrPageFaultF so it is held until the end of the memory operation
// from the datapath.
// types 5b
else if (ITLBMissF & WalkerInstrPageFaultF & AnyCPUReqM) begin // 5b
NextState = STATE_PTW_FAULT_READY;
DCacheStall = 1'b1;
SelAdrM = 2'b01;
end
// in this branch we stay in ptw_ready because we are doing an itlb walk
// after a dtlb walk.
// types 7a and 7b.
else if (DTLBMissM & DTLBWriteM & ITLBMissF)begin
NextState = STATE_PTW_READY;
DCacheStall = 1'b0;
// read hit valid cached
end else if(MemRWM[1] & CacheableM & ~ExceptionM & CacheHit) begin
NextState = STATE_PTW_READY;
DCacheStall = 1'b0;
LRUWriteEn = 1'b1;
end
// read miss valid cached
else if(SelPTW & MemRWM[1] & CacheableM & ~ExceptionM & ~CacheHit) begin
NextState = STATE_PTW_READ_MISS_FETCH_WDV;
CntReset = 1'b1;
DCacheStall = 1'b1;
end
else begin
NextState = STATE_PTW_READY;
DCacheStall = 1'b0;
end
end
STATE_PTW_READ_MISS_FETCH_WDV: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBRead = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
if(FetchCountFlag & AHBAck) begin
NextState = STATE_PTW_READ_MISS_FETCH_DONE;
end else begin
NextState = STATE_PTW_READ_MISS_FETCH_WDV;
end
end
STATE_PTW_READ_MISS_FETCH_DONE: begin
DCacheStall = 1'b1;
SelAdrM = 2'b10;
CntReset = 1'b1;
CommittedM = 1'b1;
CntReset = 1'b1;
if(VictimDirty) begin
NextState = STATE_PTW_READ_MISS_EVICT_DIRTY;
end else begin
NextState = STATE_PTW_READ_MISS_WRITE_CACHE_BLOCK;
end
end
STATE_PTW_READ_MISS_EVICT_DIRTY: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBWrite = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
SelEvict = 1'b1;
if(FetchCountFlag & AHBAck) begin
NextState = STATE_PTW_READ_MISS_WRITE_CACHE_BLOCK;
end else begin
NextState = STATE_PTW_READ_MISS_EVICT_DIRTY;
end
end
STATE_PTW_READ_MISS_WRITE_CACHE_BLOCK: begin
SRAMBlockWriteEnableM = 1'b1;
DCacheStall = 1'b1;
NextState = STATE_PTW_READ_MISS_READ_WORD;
SelAdrM = 2'b10;
SetValid = 1'b1;
ClearDirty = 1'b1;
CommittedM = 1'b1;
//LRUWriteEn = 1'b1;
end
STATE_PTW_READ_MISS_READ_WORD: begin
SelAdrM = 2'b10;
DCacheStall = 1'b1;
CommittedM = 1'b1;
NextState = STATE_PTW_READ_MISS_READ_WORD_DELAY;
end
STATE_PTW_READ_MISS_READ_WORD_DELAY: begin
SelAdrM = 2'b10;
NextState = STATE_PTW_READY;
CommittedM = 1'b1;
end
STATE_PTW_ACCESS_AFTER_WALK: begin
DCacheStall = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
LRUWriteEn = 1'b1;
NextState = STATE_READY;
end
STATE_CPU_BUSY: begin
CommittedM = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
STATE_CPU_BUSY_FINISH_AMO: begin
CommittedM = 1'b1;
SelAdrM = 2'b10;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY_FINISH_AMO;
end
else begin
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
LRUWriteEn = 1'b1;
NextState = STATE_READY;
end
end
STATE_UNCACHED_WRITE : begin
DCacheStall = 1'b1;
AHBWrite = 1'b1;
CommittedM = 1'b1;
if(AHBAck) begin
NextState = STATE_UNCACHED_WRITE_DONE;
end else begin
NextState = STATE_UNCACHED_WRITE;
end
end
STATE_UNCACHED_READ : begin
DCacheStall = 1'b1;
AHBRead = 1'b1;
CommittedM = 1'b1;
if(AHBAck) begin
NextState = STATE_UNCACHED_READ_DONE;
end else begin
NextState = STATE_UNCACHED_READ;
end
end
STATE_UNCACHED_WRITE_DONE: begin
CommittedM = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
STATE_UNCACHED_READ_DONE: begin
CommittedM = 1'b1;
SelUncached = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
NextState = STATE_READY;
end
end
// itlb => instruction page fault states with memory request.
STATE_PTW_FAULT_READY: begin
// read hit valid cached
if(MemRWM[1] & CacheableM & CacheHit & ~DTLBMissM) begin
DCacheStall = 1'b0;
DCacheAccess = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
// write hit valid cached
else if (MemRWM[0] & CacheableM & CacheHit & ~DTLBMissM) begin
SelAdrM = 2'b10;
DCacheStall = 1'b0;
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
// read or write miss valid cached
else if((|MemRWM) & CacheableM & ~CacheHit & ~DTLBMissM) begin
NextState = STATE_PTW_FAULT_MISS_FETCH_WDV;
CntReset = 1'b1;
DCacheStall = 1'b1;
DCacheAccess = 1'b1;
DCacheMiss = 1'b1;
end
// uncached write
else if(MemRWM[0] & ~CacheableM & ~DTLBMissM) begin
NextState = STATE_PTW_FAULT_UNCACHED_WRITE;
CntReset = 1'b1;
DCacheStall = 1'b1;
AHBWrite = 1'b1;
end
// uncached read
else if(MemRWM[1] & ~CacheableM & ~DTLBMissM) begin
NextState = STATE_PTW_FAULT_UNCACHED_READ;
CntReset = 1'b1;
DCacheStall = 1'b1;
AHBRead = 1'b1;
end
// fault
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
STATE_PTW_FAULT_CPU_BUSY: begin
CommittedM = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
STATE_PTW_FAULT_MISS_FETCH_WDV: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBRead = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
if(FetchCountFlag & AHBAck) begin
NextState = STATE_PTW_FAULT_MISS_FETCH_DONE;
end else begin
NextState = STATE_PTW_FAULT_MISS_FETCH_WDV;
end
end
STATE_PTW_FAULT_MISS_FETCH_DONE: begin
DCacheStall = 1'b1;
SelAdrM = 2'b10;
CntReset = 1'b1;
CommittedM = 1'b1;
if(VictimDirty) begin
NextState = STATE_PTW_FAULT_MISS_EVICT_DIRTY;
end else begin
NextState = STATE_PTW_FAULT_MISS_WRITE_CACHE_BLOCK;
end
end
STATE_PTW_FAULT_MISS_WRITE_CACHE_BLOCK: begin
SRAMBlockWriteEnableM = 1'b1;
DCacheStall = 1'b1;
NextState = STATE_PTW_FAULT_MISS_READ_WORD;
SelAdrM = 2'b10;
SetValid = 1'b1;
ClearDirty = 1'b1;
CommittedM = 1'b1;
//LRUWriteEn = 1'b1; // DO not update LRU on SRAM fetch update. Wait for subsequent read/write
end
STATE_PTW_FAULT_MISS_READ_WORD: begin
SelAdrM = 2'b10;
DCacheStall = 1'b1;
CommittedM = 1'b1;
if(MemRWM[1]) begin
NextState = STATE_PTW_FAULT_MISS_READ_WORD_DELAY;
// delay state is required as the read signal MemRWM[1] is still high when we
// return to the ready state because the cache is stalling the cpu.
end else begin
NextState = STATE_PTW_FAULT_MISS_WRITE_WORD;
end
end
STATE_PTW_FAULT_MISS_READ_WORD_DELAY: begin
CommittedM = 1'b1;
LRUWriteEn = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
STATE_PTW_FAULT_MISS_WRITE_WORD: begin
SRAMWordWriteEnableM = 1'b1;
SetDirty = 1'b1;
SelAdrM = 2'b10;
DCacheStall = 1'b1;
CommittedM = 1'b1;
LRUWriteEn = 1'b1;
NextState = STATE_PTW_FAULT_MISS_WRITE_WORD_DELAY;
end
STATE_PTW_FAULT_MISS_WRITE_WORD_DELAY: begin
CommittedM = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
STATE_PTW_FAULT_MISS_EVICT_DIRTY: begin
DCacheStall = 1'b1;
PreCntEn = 1'b1;
AHBWrite = 1'b1;
SelAdrM = 2'b10;
CommittedM = 1'b1;
SelEvict = 1'b1;
if(FetchCountFlag & AHBAck) begin
NextState = STATE_PTW_FAULT_MISS_WRITE_CACHE_BLOCK;
end else begin
NextState = STATE_PTW_FAULT_MISS_EVICT_DIRTY;
end
end
STATE_PTW_FAULT_UNCACHED_WRITE : begin
DCacheStall = 1'b1;
AHBWrite = 1'b1;
CommittedM = 1'b1;
if(AHBAck) begin
NextState = STATE_PTW_FAULT_UNCACHED_WRITE_DONE;
end else begin
NextState = STATE_PTW_FAULT_UNCACHED_WRITE;
end
end
STATE_PTW_FAULT_UNCACHED_READ : begin
DCacheStall = 1'b1;
AHBRead = 1'b1;
CommittedM = 1'b1;
if(AHBAck) begin
NextState = STATE_PTW_FAULT_UNCACHED_READ_DONE;
end else begin
NextState = STATE_PTW_FAULT_UNCACHED_READ;
end
end
STATE_PTW_FAULT_UNCACHED_WRITE_DONE: begin
CommittedM = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
STATE_PTW_FAULT_UNCACHED_READ_DONE: begin
CommittedM = 1'b1;
SelUncached = 1'b1;
if(StallWtoDCache) begin
NextState = STATE_PTW_FAULT_CPU_BUSY;
SelAdrM = 2'b10;
end
else begin
MemAfterIWalkDone = 1'b1;
NextState = STATE_READY;
end
end
default: begin
end
endcase
end
endmodule // dcachefsm

185
wally-pipelined/src/lsu/subwordread.sv
View File

@ -26,13 +26,10 @@
`include "wally-config.vh"
module subwordread (
// from AHB Interface
input logic [`XLEN-1:0] HRDATA,
input logic [2:0] HADDRD,
//input logic UnsignedLoadM,
input logic [3:0] HSIZED,
// to ifu/dmems
output logic [`XLEN-1:0] HRDATAMasked
input logic [`XLEN-1:0] ReadDataWordMuxM,
input logic [2:0] MemPAdrM,
input logic [2:0] Funct3M,
output logic [`XLEN-1:0] ReadDataM
);
logic [7:0] ByteM;
@ -40,8 +37,8 @@ module subwordread (
logic [`XLEN-1:0] offset0, offset1, offset2, offset3;
// HSIZED[3] is the unsigned bit. mask upper bits.
// HSIZED[1:0] is the size of the memory access.
// Funct3M[2] is the unsigned bit. mask upper bits.
// Funct3M[1:0] is the size of the memory access.
generate
if (`XLEN == 64) begin
@ -50,52 +47,52 @@ module subwordread (
logic [`XLEN-1:0] offset4, offset5, offset6, offset7;
always_comb
case(HSIZED[1:0])
3: offset0 = HRDATA; //ld
2: offset0 = HSIZED[3] ? {{32'b0}, HRDATA[31:0]} : {{32{HRDATA[31]}}, HRDATA[31:0]}; //lw(u)
1: offset0 = HSIZED[3] ? {{48'b0}, HRDATA[15:0]} : {{48{HRDATA[15]}}, HRDATA[15:0]}; //lh(u)
0: offset0 = HSIZED[3] ? {{56'b0}, HRDATA[7:0]} : {{56{HRDATA[7]}}, HRDATA[7:0]}; //lb(u)
case(Funct3M[1:0])
3: offset0 = ReadDataWordMuxM; //ld
2: offset0 = Funct3M[2] ? {{32'b0}, ReadDataWordMuxM[31:0]} : {{32{ReadDataWordMuxM[31]}}, ReadDataWordMuxM[31:0]}; //lw(u)
1: offset0 = Funct3M[2] ? {{48'b0}, ReadDataWordMuxM[15:0]} : {{48{ReadDataWordMuxM[15]}}, ReadDataWordMuxM[15:0]}; //lh(u)
0: offset0 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[7:0]} : {{56{ReadDataWordMuxM[7]}}, ReadDataWordMuxM[7:0]}; //lb(u)
endcase
assign offset1 = HSIZED[3] ? {{56'b0}, HRDATA[15:8]} : {{56{HRDATA[15]}}, HRDATA[15:8]}; //lb(u)
assign offset1 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[15:8]} : {{56{ReadDataWordMuxM[15]}}, ReadDataWordMuxM[15:8]}; //lb(u)
always_comb
case(HSIZED[0])
1: offset2 = HSIZED[3] ? {{48'b0}, HRDATA[31:16]} : {{48{HRDATA[31]}}, HRDATA[31:16]};//lh(u)
0: offset2 = HSIZED[3] ? {{56'b0}, HRDATA[23:16]} : {{56{HRDATA[23]}}, HRDATA[23:16]};//lb(u)
case(Funct3M[0])
1: offset2 = Funct3M[2] ? {{48'b0}, ReadDataWordMuxM[31:16]} : {{48{ReadDataWordMuxM[31]}}, ReadDataWordMuxM[31:16]};//lh(u)
0: offset2 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[23:16]} : {{56{ReadDataWordMuxM[23]}}, ReadDataWordMuxM[23:16]};//lb(u)
endcase
assign offset3 = HSIZED[3] ? {{56'b0}, HRDATA[31:24]} : {{56{HRDATA[31]}}, HRDATA[31:24]};//lb(u)
assign offset3 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[31:24]} : {{56{ReadDataWordMuxM[31]}}, ReadDataWordMuxM[31:24]};//lb(u)
always_comb
case(HSIZED[1:0])
3: offset4 = HSIZED[3] ? {{32'b0}, HRDATA[63:32]} : {{32{HRDATA[63]}}, HRDATA[63:32]};//ld(u) // unaligned will cause fault.
2: offset4 = HSIZED[3] ? {{32'b0}, HRDATA[63:32]} : {{32{HRDATA[63]}}, HRDATA[63:32]};//lw(u)
1: offset4 = HSIZED[3] ? {{48'b0}, HRDATA[47:32]} : {{48{HRDATA[47]}}, HRDATA[47:32]};//lh(u)
0: offset4 = HSIZED[3] ? {{56'b0}, HRDATA[39:32]} : {{56{HRDATA[39]}}, HRDATA[39:32]};//lb(u)
case(Funct3M[1:0])
3: offset4 = Funct3M[2] ? {{32'b0}, ReadDataWordMuxM[63:32]} : {{32{ReadDataWordMuxM[63]}}, ReadDataWordMuxM[63:32]};//ld(u) // unaligned will cause fault.
2: offset4 = Funct3M[2] ? {{32'b0}, ReadDataWordMuxM[63:32]} : {{32{ReadDataWordMuxM[63]}}, ReadDataWordMuxM[63:32]};//lw(u)
1: offset4 = Funct3M[2] ? {{48'b0}, ReadDataWordMuxM[47:32]} : {{48{ReadDataWordMuxM[47]}}, ReadDataWordMuxM[47:32]};//lh(u)
0: offset4 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[39:32]} : {{56{ReadDataWordMuxM[39]}}, ReadDataWordMuxM[39:32]};//lb(u)
endcase
assign offset5 = HSIZED[3] ? {{56'b0}, HRDATA[47:40]} : {{56{HRDATA[47]}}, HRDATA[47:40]};//lb(u)
assign offset5 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[47:40]} : {{56{ReadDataWordMuxM[47]}}, ReadDataWordMuxM[47:40]};//lb(u)
always_comb
case(HSIZED[0])
1: offset6 = HSIZED[3] ? {{48'b0}, HRDATA[63:48]} : {{48{HRDATA[63]}}, HRDATA[63:48]};//lh(u)
0: offset6 = HSIZED[3] ? {{56'b0}, HRDATA[55:48]} : {{56{HRDATA[55]}}, HRDATA[55:48]};//lb(u)
case(Funct3M[0])
1: offset6 = Funct3M[2] ? {{48'b0}, ReadDataWordMuxM[63:48]} : {{48{ReadDataWordMuxM[63]}}, ReadDataWordMuxM[63:48]};//lh(u)
0: offset6 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[55:48]} : {{56{ReadDataWordMuxM[55]}}, ReadDataWordMuxM[55:48]};//lb(u)
endcase
assign offset7 = HSIZED[3] ? {{56'b0}, HRDATA[63:56]} : {{56{HRDATA[63]}}, HRDATA[63:56]};//lb(u)
assign offset7 = Funct3M[2] ? {{56'b0}, ReadDataWordMuxM[63:56]} : {{56{ReadDataWordMuxM[63]}}, ReadDataWordMuxM[63:56]};//lb(u)
// address mux
always_comb
case(HADDRD[2:0])
0: HRDATAMasked = offset0;
1: HRDATAMasked = offset1;
2: HRDATAMasked = offset2;
3: HRDATAMasked = offset3;
4: HRDATAMasked = offset4;
5: HRDATAMasked = offset5;
6: HRDATAMasked = offset6;
7: HRDATAMasked = offset7;
case(MemPAdrM[2:0])
0: ReadDataM = offset0;
1: ReadDataM = offset1;
2: ReadDataM = offset2;
3: ReadDataM = offset3;
4: ReadDataM = offset4;
5: ReadDataM = offset5;
6: ReadDataM = offset6;
7: ReadDataM = offset7;
endcase
// easier to understand but slower
@ -103,45 +100,45 @@ module subwordread (
/* -----\/----- EXCLUDED -----\/-----
// ByteMe mux
always_comb
case(HADDRD[2:0])
3'b000: ByteM = HRDATA[7:0];
3'b001: ByteM = HRDATA[15:8];
3'b010: ByteM = HRDATA[23:16];
3'b011: ByteM = HRDATA[31:24];
3'b100: ByteM = HRDATA[39:32];
3'b101: ByteM = HRDATA[47:40];
3'b110: ByteM = HRDATA[55:48];
3'b111: ByteM = HRDATA[63:56];
case(MemPAdrM[2:0])
3'b000: ByteM = ReadDataWordMuxM[7:0];
3'b001: ByteM = ReadDataWordMuxM[15:8];
3'b010: ByteM = ReadDataWordMuxM[23:16];
3'b011: ByteM = ReadDataWordMuxM[31:24];
3'b100: ByteM = ReadDataWordMuxM[39:32];
3'b101: ByteM = ReadDataWordMuxM[47:40];
3'b110: ByteM = ReadDataWordMuxM[55:48];
3'b111: ByteM = ReadDataWordMuxM[63:56];
endcase
// halfword mux
always_comb
case(HADDRD[2:1])
2'b00: HalfwordM = HRDATA[15:0];
2'b01: HalfwordM = HRDATA[31:16];
2'b10: HalfwordM = HRDATA[47:32];
2'b11: HalfwordM = HRDATA[63:48];
case(MemPAdrM[2:1])
2'b00: HalfwordM = ReadDataWordMuxM[15:0];
2'b01: HalfwordM = ReadDataWordMuxM[31:16];
2'b10: HalfwordM = ReadDataWordMuxM[47:32];
2'b11: HalfwordM = ReadDataWordMuxM[63:48];
endcase
logic [31:0] WordM;
always_comb
case(HADDRD[2])
1'b0: WordM = HRDATA[31:0];
1'b1: WordM = HRDATA[63:32];
case(MemPAdrM[2])
1'b0: WordM = ReadDataWordMuxM[31:0];
1'b1: WordM = ReadDataWordMuxM[63:32];
endcase
// sign extension
always_comb
case({HSIZED[3], HSIZED[1:0]}) // HSIZED[3] indicates unsigned load
3'b000: HRDATAMasked = {{56{ByteM[7]}}, ByteM}; // lb
3'b001: HRDATAMasked = {{48{HalfwordM[15]}}, HalfwordM[15:0]}; // lh
3'b010: HRDATAMasked = {{32{WordM[31]}}, WordM[31:0]}; // lw
3'b011: HRDATAMasked = HRDATA; // ld
3'b100: HRDATAMasked = {56'b0, ByteM[7:0]}; // lbu
3'b101: HRDATAMasked = {48'b0, HalfwordM[15:0]}; // lhu
3'b110: HRDATAMasked = {32'b0, WordM[31:0]}; // lwu
default: HRDATAMasked = HRDATA; // Shouldn't happen
case({Funct3M[2], Funct3M[1:0]}) // Funct3M[2] indicates unsigned load
3'b000: ReadDataM = {{56{ByteM[7]}}, ByteM}; // lb
3'b001: ReadDataM = {{48{HalfwordM[15]}}, HalfwordM[15:0]}; // lh
3'b010: ReadDataM = {{32{WordM[31]}}, WordM[31:0]}; // lw
3'b011: ReadDataM = ReadDataWordMuxM; // ld
3'b100: ReadDataM = {56'b0, ByteM[7:0]}; // lbu
3'b101: ReadDataM = {48'b0, HalfwordM[15:0]}; // lhu
3'b110: ReadDataM = {32'b0, WordM[31:0]}; // lwu
default: ReadDataM = ReadDataWordMuxM; // Shouldn't happen
endcase
-----/\----- EXCLUDED -----/\----- */
end else begin // 32-bit
@ -149,58 +146,58 @@ module subwordread (
// fast but more complex
always_comb
case(HSIZED[1:0])
3: offset0 = HRDATA; //ld illegal
2: offset0 = HRDATA[31:0]; //lw
1: offset0 = HSIZED[3] ? {{16'b0}, HRDATA[15:0]} : {{16{HRDATA[15]}}, HRDATA[15:0]}; //lh(u)
0: offset0 = HSIZED[3] ? {{24'b0}, HRDATA[7:0]} : {{24{HRDATA[7]}}, HRDATA[7:0]}; //lb(u)
case(Funct3M[1:0])
3: offset0 = ReadDataWordMuxM; //ld illegal
2: offset0 = ReadDataWordMuxM[31:0]; //lw
1: offset0 = Funct3M[2] ? {{16'b0}, ReadDataWordMuxM[15:0]} : {{16{ReadDataWordMuxM[15]}}, ReadDataWordMuxM[15:0]}; //lh(u)
0: offset0 = Funct3M[2] ? {{24'b0}, ReadDataWordMuxM[7:0]} : {{24{ReadDataWordMuxM[7]}}, ReadDataWordMuxM[7:0]}; //lb(u)
endcase
assign offset1 = HSIZED[3] ? {{24'b0}, HRDATA[15:8]} : {{24{HRDATA[15]}}, HRDATA[15:8]}; //lb(u)
assign offset1 = Funct3M[2] ? {{24'b0}, ReadDataWordMuxM[15:8]} : {{24{ReadDataWordMuxM[15]}}, ReadDataWordMuxM[15:8]}; //lb(u)
always_comb
case(HSIZED[0])
1: offset2 = HSIZED[3] ? {{16'b0}, HRDATA[31:16]} : {{16{HRDATA[31]}}, HRDATA[31:16]};//lh(u)
0: offset2 = HSIZED[3] ? {{24'b0}, HRDATA[23:16]} : {{24{HRDATA[23]}}, HRDATA[23:16]};//lb(u)
case(Funct3M[0])
1: offset2 = Funct3M[2] ? {{16'b0}, ReadDataWordMuxM[31:16]} : {{16{ReadDataWordMuxM[31]}}, ReadDataWordMuxM[31:16]};//lh(u)
0: offset2 = Funct3M[2] ? {{24'b0}, ReadDataWordMuxM[23:16]} : {{24{ReadDataWordMuxM[23]}}, ReadDataWordMuxM[23:16]};//lb(u)
endcase
assign offset3 = HSIZED[3] ? {{24'b0}, HRDATA[31:24]} : {{24{HRDATA[31]}}, HRDATA[31:24]};//lb(u)
assign offset3 = Funct3M[2] ? {{24'b0}, ReadDataWordMuxM[31:24]} : {{24{ReadDataWordMuxM[31]}}, ReadDataWordMuxM[31:24]};//lb(u)
// address mux
always_comb
case(HADDRD[1:0])
0: HRDATAMasked = offset0;
1: HRDATAMasked = offset1;
2: HRDATAMasked = offset2;
3: HRDATAMasked = offset3;
case(MemPAdrM[1:0])
0: ReadDataM = offset0;
1: ReadDataM = offset1;
2: ReadDataM = offset2;
3: ReadDataM = offset3;
endcase
// slow but easier to understand
/* -----\/----- EXCLUDED -----\/-----
always_comb
case(HADDRD[1:0])
2'b00: ByteM = HRDATA[7:0];
2'b01: ByteM = HRDATA[15:8];
2'b10: ByteM = HRDATA[23:16];
2'b11: ByteM = HRDATA[31:24];
case(MemPAdrM[1:0])
2'b00: ByteM = ReadDataWordMuxM[7:0];
2'b01: ByteM = ReadDataWordMuxM[15:8];
2'b10: ByteM = ReadDataWordMuxM[23:16];
2'b11: ByteM = ReadDataWordMuxM[31:24];
endcase
// halfword mux
always_comb
case(HADDRD[1])
1'b0: HalfwordM = HRDATA[15:0];
1'b1: HalfwordM = HRDATA[31:16];
case(MemPAdrM[1])
1'b0: HalfwordM = ReadDataWordMuxM[15:0];
1'b1: HalfwordM = ReadDataWordMuxM[31:16];
endcase
// sign extension
always_comb
case({HSIZED[3], HSIZED[1:0]})
3'b000: HRDATAMasked = {{24{ByteM[7]}}, ByteM}; // lb
3'b001: HRDATAMasked = {{16{HalfwordM[15]}}, HalfwordM[15:0]}; // lh
3'b010: HRDATAMasked = HRDATA; // lw
3'b100: HRDATAMasked = {24'b0, ByteM[7:0]}; // lbu
3'b101: HRDATAMasked = {16'b0, HalfwordM[15:0]}; // lhu
default: HRDATAMasked = HRDATA;
case({Funct3M[2], Funct3M[1:0]})
3'b000: ReadDataM = {{24{ByteM[7]}}, ByteM}; // lb
3'b001: ReadDataM = {{16{HalfwordM[15]}}, HalfwordM[15:0]}; // lh
3'b010: ReadDataM = ReadDataWordMuxM; // lw
3'b100: ReadDataM = {24'b0, ByteM[7:0]}; // lbu
3'b101: ReadDataM = {16'b0, HalfwordM[15:0]}; // lhu
default: ReadDataM = ReadDataWordMuxM;
endcase
-----/\----- EXCLUDED -----/\----- */
end