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`include "core/uarch.sv"
module core_fetch
#(parameter PREFETCH_ORDER=2)
(
input logic clk,
rst_n,
stall,
fetched,
explicit_branch,
wr_pc,
prefetch_flush,
input ptr branch_target,
input word wr_current,
fetch_data,
output logic fetch,
flush,
output word insn,
output ptr insn_pc,
addr,
fetch_head
);
ptr next_pc, hold_addr, target;
logic branch, prefetch_ready, fetched_valid, discard, pending, next_pending;
assign fetch = prefetch_ready && !discard;
assign flush = branch || prefetch_flush;
assign branch = explicit_branch || wr_pc;
assign target = wr_pc ? wr_current[31:2] : branch_target; //TODO: alignment exception
assign next_pending = fetch || (pending && !fetched);
assign fetched_valid = fetched && !discard;
core_prefetch #(.ORDER(PREFETCH_ORDER)) prefetch
(
.head(fetch_head),
.fetched(fetched_valid),
.fetch(prefetch_ready),
.*
);
always_comb begin
if(branch)
fetch_head = target;
else if(prefetch_flush)
fetch_head = next_pc;
else
fetch_head = {30{1'bx}};
if(flush)
addr = fetch_head;
else if(fetch && fetched_valid)
addr = hold_addr + 1;
else
addr = hold_addr;
end
always_ff @(posedge clk or negedge rst_n)
if(!rst_n) begin
pending <= 0;
discard <= 0;
hold_addr <= 0;
end else begin
pending <= next_pending;
discard <= next_pending && (discard || flush);
hold_addr <= addr;
end
endmodule
|
