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`include "gfx/gfx_defs.sv"
module fold_flow
(
input logic clk,
rst_n,
input logic in_valid,
out_ready,
output logic in_ready,
out_valid,
stall,
feedback,
feedback_last
);
index4 rounds[`FP_ADD_STAGES], last_round;
assign stall = out_valid && !out_ready;
assign in_ready = !stall && !feedback;
assign out_valid = last_round == `INDEX4_MAX;
assign feedback = last_round[1] ^ last_round[0];
assign feedback_last = last_round[1];
assign last_round = rounds[`FP_ADD_STAGES - 1];
always_ff @(posedge clk or negedge rst_n)
if (!rst_n)
rounds[0] <= `INDEX4_MIN;
else if (!stall)
unique case (last_round)
2'b01:
rounds[0] <= 2'b10;
2'b10:
rounds[0] <= 2'b11;
2'b00, 2'b11:
rounds[0] <= {1'b0, in_valid};
endcase
genvar i;
generate
for (i = 1; i < `FP_ADD_STAGES; ++i) begin: pipeline
always_ff @(posedge clk or negedge rst_n)
if (!rst_n)
rounds[i] <= `INDEX4_MIN;
else if (in_ready)
rounds[i] <= rounds[i - 1];
end
endgenerate
endmodule
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