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changed tlbphysicalpagemask to structural

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This commit is contained in:
David Harris 2021-07-06 17:08:04 -04:00
parent fd0cd930a7
commit f960561cbb
1 changed files with 14 additions and 3 deletions
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17
wally-pipelined/src/mmu/tlbphysicalpagemask.sv
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@ -40,8 +40,19 @@ module tlbphysicalpagemask (
logic [`PPN_BITS-1:0] PageNumberMask;
generate
if (`XLEN == 32) begin
always_comb
if (`XLEN == 32)
// kilopage: 22 bits of PPN, 0 bits of VPN
// megapage: 12 bits of PPN, 10 bits of VPN
mux2 #(22) pnm(22'h3FFFFF, 22'h3FFC00, PageType[0], PageNumberMask);
else
// kilopage: 44 bits of PPN, 0 bits of VPN
// megapage: 35 bits of PPN, 9 bits of VPN
// gigapage: 26 bits of PPN, 18 bits of VPN
// terapage: 17 bits of PPN, 27 bits of VPN
mux4 #(44) pnm(44'hFFFFFFFFFFF, 44'hFFFFFFFFE00, 44'hFFFFFFC0000, 44'hFFFF8000000, PageType, PageNumberMask);
endgenerate
/* always_comb
case (PageType[0])
// the widths of these constansts are hardocded here to match `PPN_BITS in the wally-constants file.
0: PageNumberMask = 22'h3FFFFF; // kilopage: 22 bits of PPN, 0 bits of VPN
@ -59,7 +70,7 @@ module tlbphysicalpagemask (
// in the tlb when it generates VPN from the full virtualadress.
endcase
end
endgenerate
endgenerate */
// merge low segments of VPN with high segments of PPN decided by the pagetype.
assign ZeroExtendedVPN = {{EXTRA_BITS{1'b0}}, VPN}; // forces the VPN to be the same width as PPN.