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Eliminate transitions to FLUSH and WRITEBACK in cachefsm for READ_ONLY_CACHE

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This commit is contained in:
David Harris 2023-03-19 10:41:47 -07:00
parent 3fa570835a
commit cd0240d938
2 changed files with 9 additions and 9 deletions
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2
src/cache/cache.sv vendored
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@ -197,7 +197,7 @@ module cache #(parameter LINELEN, NUMLINES, NUMWAYS, LOGBWPL, WORDLEN, MUXINTE
// Cache FSM
/////////////////////////////////////////////////////////////////////////////////////////////
cachefsm cachefsm(.clk, .reset, .CacheBusRW, .CacheBusAck,
cachefsm #(READ_ONLY_CACHE) cachefsm(.clk, .reset, .CacheBusRW, .CacheBusAck,
.FlushStage, .CacheRW, .CacheAtomic, .Stall,
.CacheHit, .LineDirty, .CacheStall, .CacheCommitted,
.CacheMiss, .CacheAccess, .SelAdr,

16
src/cache/cachefsm.sv vendored
View File

@ -29,7 +29,7 @@
`include "wally-config.vh"
module cachefsm (
module cachefsm #(parameter READ_ONLY_CACHE = 0) (
input logic clk,
input logic reset,
// hazard and privilege unit
@ -112,8 +112,8 @@ module cachefsm (
NextState = STATE_READY;
case (CurrState)
STATE_READY: if(InvalidateCache) NextState = STATE_READY;
else if(FlushCache) NextState = STATE_FLUSH;
else if(AnyMiss & ~LineDirty) NextState = STATE_FETCH;
else if(FlushCache & ~READ_ONLY_CACHE) NextState = STATE_FLUSH;
else if(AnyMiss & (READ_ONLY_CACHE | ~LineDirty)) NextState = STATE_FETCH;
else if(AnyMiss & LineDirty) NextState = STATE_WRITEBACK;
else NextState = STATE_READY;
STATE_FETCH: if(CacheBusAck) NextState = STATE_WRITE_LINE;
@ -125,11 +125,11 @@ module cachefsm (
else NextState = STATE_WRITEBACK;
// eviction needs a delay as the bus fsm does not correctly handle sending the write command at the same time as getting back the bus ack.
STATE_FLUSH: if(LineDirty) NextState = STATE_FLUSH_WRITEBACK;
else if (FlushFlag) NextState = STATE_READ_HOLD;
else NextState = STATE_FLUSH;
STATE_FLUSH_WRITEBACK: if(CacheBusAck & ~FlushFlag) NextState = STATE_FLUSH;
else if(CacheBusAck) NextState = STATE_READ_HOLD;
else NextState = STATE_FLUSH_WRITEBACK;
else if (FlushFlag) NextState = STATE_READ_HOLD;
else NextState = STATE_FLUSH;
STATE_FLUSH_WRITEBACK: if(CacheBusAck & ~FlushFlag) NextState = STATE_FLUSH;
else if(CacheBusAck) NextState = STATE_READ_HOLD;
else NextState = STATE_FLUSH_WRITEBACK;
default: NextState = STATE_READY;
endcase
end