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`include "core/uarch.sv"
module core_prefetch
#(parameter ORDER=2)
(
input logic clk,
stall,
flush,
fetched,
input word fetch_data,
input ptr head,
output word insn,
output ptr insn_pc,
next_pc,
output logic fetch
);
localparam SIZE = (1 << ORDER) - 1;
logic[31:0] prefetch[SIZE];
logic[ORDER - 1:0] valid;
assign insn = flush ? `NOP : prefetch[0];
assign next_pc = ~stall & |valid ? insn_pc + 1 : insn_pc;
always_comb
if((valid == SIZE - 2) & fetched)
fetch = 0;
else
fetch = ~&valid;
always_ff @(posedge clk) begin
insn_pc <= flush ? head : next_pc;
if(~flush & fetched & (valid == SIZE - 1))
prefetch[SIZE - 1] <= fetch_data;
else
prefetch[SIZE - 1] <= `NOP;
if(flush)
valid <= 0;
else if(fetched & ((stall & ~&valid) | ~|valid))
valid <= valid + 1;
else if(~stall & ~fetched & |valid)
valid <= valid - 1;
end
genvar i;
generate
for(i = 0; i < SIZE - 1; ++i) begin: prefetch_slots
always_ff @(posedge clk)
if(flush)
prefetch[i] <= `NOP;
else if(fetched & (~(|i | |valid) | (valid == i + {{(ORDER - 1){1'b0}}, ~stall})))
prefetch[i] <= fetch_data;
else if(~stall)
prefetch[i] <= prefetch[i + 1];
initial prefetch[i] = `NOP;
end
endgenerate
initial begin
insn_pc = 0;
valid = 0;
prefetch[SIZE - 1] = `NOP;
end
endmodule
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