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Created improved cache replacement policy implementation. This version is generic and works for any number of ways. Not fully tested and is currently commented out.

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This commit is contained in:
Ross Thompson 2022-11-16 11:15:34 -06:00
parent 6fe35ee0e3
commit 900a326a23
1 changed files with 105 additions and 0 deletions
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105
pipelined/src/cache/cachereplacementpolicy.sv vendored
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@ -46,10 +46,115 @@ module cachereplacementpolicy
logic [SETLEN-1:0] RAdrD;
logic LRUWriteEnD;
localparam LOGNUMWAYS = $clog2(NUMWAYS);
localparam LEN = NUMWAYS-1;
logic [LOGNUMWAYS-1:0] HitWayEnc;
logic [LEN-1:0] HitWayExpand;
genvar row;
logic [NUMWAYS-2:0] cEn;
/* -----\/----- EXCLUDED -----\/-----
// proposed generic solution
binencoder #(NUMWAYS) encoder(HitWay, HitWayEnc);
// bit duplication
// expand HitWay as HitWay[3], {{2}{HitWay[2]}}, {{4}{HitWay[1]}, {{8{HitWay[0]}}, ...
for(row = 0; row < LOGNUMWAYS; row++) begin
localparam integer DuplicationFactor = 2**(LOGNUMWAYS-row-1);
localparam integer StartIndex = NUMWAYS-2 - DuplicationFactor + 1;
localparam integer EndIndex = NUMWAYS-2 - 2 * DuplicationFactor + 2;
assign HitWayExpand[StartIndex : EndIndex] = {{DuplicationFactor}{HitWayEnc[row]}};
end
genvar r, a,s;
//localparam s = NUMWAYS-2;
assign cEn[NUMWAYS-2] = '1;
for(s = NUMWAYS-2; s >= NUMWAYS/2; s--) begin : enables
localparam p = NUMWAYS - s;
localparam g = $clog2(p);
localparam t0 = s - g;
localparam t1 = t0 - 1;
localparam r = LOGNUMWAYS - g;
assign cEn[t0] = cEn[s] & ~HitWayEnc[r];
assign cEn[t1] = cEn[s] & HitWayEnc[r];
end
mux2 #(1) LRUMuxes[NUMWAYS-2:0](LineReplacementBits, HitWayExpand, cEn, NewReplacement);
assign VictimWay[0] = ~LineReplacementBits[2] & ~LineReplacementBits[0];
assign VictimWay[1] = ~LineReplacementBits[2] & LineReplacementBits[0];
assign VictimWay[2] = LineReplacementBits[2] & ~LineReplacementBits[1];
assign VictimWay[3] = LineReplacementBits[2] & LineReplacementBits[1];
-----/\----- EXCLUDED -----/\----- */
/* -----\/----- EXCLUDED -----\/-----
// logic [NUMWAYS/2-1:0] rawEn [LOGNUMWAYS-1:0];
for(r = LOGNUMWAYS-1; r >= 0; r--) begin
localparam integer g = 2**(LOGNUMWAYS-r-1);
for(a = g-1; a > 0; a--) begin
localparam t0 = s - 2**(g-1);
localparam t1 = t0 - 1;
localparam s = s - 1;
assign cEn[t0] = cEn[s] & ~HitWayEnc[r];
assign cEn[t1] = cEn[s] & HitWayEnc[r];
end
-----/\----- EXCLUDED -----/\----- */
/* -----\/----- EXCLUDED -----\/-----
for(a = g-1; a > 0; a--) begin
localparam t0 = s - 2**(g-1);
localparam t1 = t0 - 1;
s = s - 1;
end
end
-----/\----- EXCLUDED -----/\----- */
/* -----\/----- EXCLUDED -----\/-----
always_comb begin
for(r = LOGNUMWAYS-1; r > 0; r--) begin
localparam g = 2**(LOGNUMWAYS-r-1);
for(a = g-1; a > 0; a--) begin
localparam t0 = s - 2**(g-1);
localparam t1 = t0 - 1;
s = s - 1;
end
end
end
-----/\----- EXCLUDED -----/\----- */
/* -----\/----- EXCLUDED -----\/-----
genvar row2;
logic [LOGNUMWAYS-1:0] indices [LOGNUMWAYS-1:0];
integer jindex;
always_comb begin
rawEn[LOGNUMWAYS-1] = 1;
for(jindex = 0; jindex < LOGNUMWAYS-1; jindex++) begin
rawEn[jindex] = 0;
rawEn[jindex][~(HitWayEnc>>(jindex+1))] = 1;
//cEn[2**(LOGNUMWAYS-jindex)-1+jindex:0] = rawEn[jindex][2**(LOGNUMWAYS-jindex)-1:0];
end
end
-----/\----- EXCLUDED -----/\----- */
// *** high priority to clean up
/* -----\/----- EXCLUDED -----\/-----
initial begin
assert (NUMWAYS == 2 || NUMWAYS == 4) else $error("Only 2 or 4 ways supported");
end
-----/\----- EXCLUDED -----/\----- */
// Replacement Bits: Register file
// Needs to be resettable for simulation, but could omit reset for synthesis ***