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Simplified VPN case statement

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This commit is contained in:
David Harris 2021-07-17 19:34:01 -04:00
parent 25450bd7c1
commit 989bb7c01b
1 changed files with 5 additions and 10 deletions
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15
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -101,7 +101,7 @@ module pagetablewalker
assign SelPTW = (WalkerState != IDLE) & (WalkerState != FAULT);
assign DTLBWriteM = (WalkerState == LEAF) & DTLBWalk;
assign ITLBWriteF = (WalkerState == LEAF) & ~DTLBWalk;
assign UseTranslationVAdr = (NextWalkerState == LEAF) || (WalkerState == LEAF);
assign UseTranslationVAdr = (NextWalkerState == LEAF) || (WalkerState == LEAF); // ***explain this logic
// Raise faults. DTLBMiss
assign WalkerInstrPageFaultF = (WalkerState == FAULT) & ~DTLBWalk;
@ -131,15 +131,10 @@ module pagetablewalker
logic [`PPN_BITS-1:0] PPN;
always_comb
case (WalkerState) // select VPN field based on HPTW state
LEVEL3_SET_ADR: VPN = TranslationVAdr[47:39];
LEVEL3_READ: VPN = TranslationVAdr[47:39];
LEVEL3: VPN = TranslationVAdr[38:30];
LEVEL2_SET_ADR: VPN = TranslationVAdr[38:30];
LEVEL2_READ: VPN = TranslationVAdr[38:30];
LEVEL2: VPN = TranslationVAdr[29:21];
LEVEL1_SET_ADR: VPN = TranslationVAdr[29:21];
LEVEL1_READ: VPN = TranslationVAdr[29:21];
default: VPN = TranslationVAdr[20:12];
LEVEL3_SET_ADR, LEVEL3_READ: VPN = TranslationVAdr[47:39];
LEVEL3, LEVEL2_SET_ADR, LEVEL2_READ: VPN = TranslationVAdr[38:30];
LEVEL2, LEVEL1_SET_ADR, LEVEL1_READ: VPN = TranslationVAdr[29:21];
default: VPN = TranslationVAdr[20:12];
endcase
assign PPN = ((WalkerState == LEVEL3_SET_ADR) | (WalkerState == LEVEL3_READ) |
(SvMode != `SV48 & ((WalkerState == LEVEL2_SET_ADR) | (WalkerState == LEVEL2_READ)))) ? BasePageTablePPN : CurrentPPN;