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Configurable Fetch Buffer works

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Co-authored-by: Vikram Krishna <vkrishna@hmc.edu>
Co-authored-by: Corey Hickson <chickson@hmc.edu>
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Jordan Carlin 2024-11-10 17:21:38 -08:00
parent ad4bc8f450
commit 1a5773a58e
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1 changed files with 15 additions and 18 deletions
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33
src/ifu/fetchbuffer.sv
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@ -34,38 +34,35 @@ module fetchbuffer import cvw::*; #(parameter cvw_t P) (
output logic FetchBufferStallF
);
localparam [31:0] nop = 32'h00000013;
logic [31:0] Readf0, Readf1, Readf2, ReadFetchBuffer;
logic [2:0] ReadPtr, WritePtr;
logic [31:0] ReadReg [P.FETCHBUFFER_ENTRIES-1:0];
logic [31:0] ReadFetchBuffer;
logic [P.FETCHBUFFER_ENTRIES-1:0] ReadPtr, WritePtr;
logic Empty, Full;
assign Empty = |(ReadPtr & WritePtr); // Bitwise and the read&write ptr, and or the bits of the result together
assign Full = |({WritePtr[1:0], WritePtr[2]} & ReadPtr); // Same as above but left rotate WritePtr to "add 1"
assign Full = |({WritePtr[P.FETCHBUFFER_ENTRIES-2:0], WritePtr[P.FETCHBUFFER_ENTRIES-1]} & ReadPtr); // Same as above but left rotate WritePtr to "add 1"
assign FetchBufferStallF = Full;
// will go in a generate block once this is parameterized
flopenl #(32) f0 (.clk, .load(reset | FlushD), .en(WritePtr[0]), .d(WriteData), .val(nop), .q(Readf0));
flopenl #(32) f1 (.clk, .load(reset | FlushD), .en(WritePtr[1]), .d(WriteData), .val(nop), .q(Readf1));
flopenl #(32) f2 (.clk, .load(reset | FlushD), .en(WritePtr[2]), .d(WriteData), .val(nop), .q(Readf2));
flopenl #(32) fbEntries[P.FETCHBUFFER_ENTRIES-1:0] (.clk, .load(reset | FlushD), .en(WritePtr), .d(WriteData), .val(nop), .q(ReadReg));
// Fetch buffer entries anded with read ptr for AO Muxing
logic [31:0] DaoArr [2:0];
// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Make parameterizable
assign DaoArr[0] = ReadPtr[0] ? Readf0 : '0;
assign DaoArr[1] = ReadPtr[1] ? Readf1 : '0;
assign DaoArr[2] = ReadPtr[2] ? Readf2 : '0;
logic [31:0] DaoArr [P.FETCHBUFFER_ENTRIES-1:0];
or_rows #(3, 32) ReadFBAOMux(.a(DaoArr), .y(ReadFetchBuffer));
// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Make parameterizable
for (genvar i = 0; i < P.FETCHBUFFER_ENTRIES; i++) begin
assign DaoArr[i] = ReadPtr[i] ? ReadReg[i] : '0;
end
or_rows #(P.FETCHBUFFER_ENTRIES, 32) ReadFBAOMux(.a(DaoArr), .y(ReadFetchBuffer));
assign ReadData = Empty ? nop : ReadFetchBuffer;
always_ff @(posedge clk) begin : shiftRegister
if (reset) begin
WritePtr <= 3'b001;
ReadPtr <= 3'b001;
WritePtr <= {{P.FETCHBUFFER_ENTRIES-1{1'b0}}, 1'b1};
ReadPtr <= {{P.FETCHBUFFER_ENTRIES-1{1'b0}}, 1'b1};
end else begin
WritePtr <= ~(Full | StallF) ? {WritePtr[1:0], WritePtr[2]} : WritePtr;
ReadPtr <= ~(StallD | Empty) ? {ReadPtr[1:0], ReadPtr[2]} : ReadPtr;
WritePtr <= ~(Full | StallF) ? {WritePtr[P.FETCHBUFFER_ENTRIES-2:0], WritePtr[P.FETCHBUFFER_ENTRIES-1]} : WritePtr;
ReadPtr <= ~(StallD | Empty) ? {ReadPtr[P.FETCHBUFFER_ENTRIES-2:0], ReadPtr[P.FETCHBUFFER_ENTRIES-1]} : ReadPtr;
end
end
endmodule