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`include "defs.svh"
module mem_arbiter
( input bit clock
, input bit reset
, output bit command_ready
, input bit command_valid
, input ram_command_t command_data
, output bit [`NUM_PDPS-1:0] pdp_ready
, input bit [`NUM_PDPS-1:0] pdp_valid
, input pdp_command_t [`NUM_PDPS-1:0] pdp_data
, input bit ram_ready
, output bit ram_valid
, output ram_command_t ram_data
);
bit [`NUM_PDPS:0] hold_valid;
ram_command_t [`NUM_PDPS:0] hold_data;
bit [$clog2(`NUM_PDPS+1):0] selector;
always @(posedge clock) begin
if (reset) begin
command_ready = 0;
for (int i = 0; i < `NUM_PDPS; ++i)
pdp_ready[i] = 0;
ram_valid = 0;
for (int i = 0; i < `NUM_PDPS+1; ++i)
hold_valid[i] = 0;
selector = 0;
end else begin
automatic bit selector_stale = 0;
if (ram_ready) ram_valid = 0;
if (!ram_valid && hold_valid[selector]) begin
ram_valid = 1;
ram_data = hold_data[selector];
hold_valid[selector] = 0;
selector_stale = 1;
end
if (hold_valid == 0) begin
if (command_ready && command_valid) begin
hold_valid[0] = 1;
hold_data[0] = command_data;
hold_data[0].tag = 0;
end
for (int i = 0; i < `NUM_PDPS; ++i) begin
if (pdp_ready[i] && pdp_valid[i]) begin
hold_valid[i+1] = 1;
hold_data[i+1].address[`RAM_ADDRESS_BITS-1:`PDP_ADDRESS_BITS] = i;
hold_data[i+1].address[`PDP_ADDRESS_BITS-1:$clog2(`RAM_LINE_WORDS)] = pdp_data[i].address;
hold_data[i+1].write = pdp_data[i].write;
hold_data[i+1].data = pdp_data[i].data;
hold_data[i+1].mask = pdp_data[i].mask;
hold_data[i+1].tag = i+1;
end
end
end
if (hold_valid != 0 && !ram_valid) begin
for (int i = 0; i < `NUM_PDPS+1; ++i) begin
if (hold_valid == 1 << i) begin
ram_valid = 1;
ram_data = hold_data[i];
hold_valid[i] = 0;
break;
end
end
end
if (hold_valid != 0 && (selector_stale || !ram_valid)) begin
for (int i = 0; i < `NUM_PDPS+1; ++i) begin
automatic int j = selector + i;
if (j > `NUM_PDPS)
j -= `NUM_PDPS+1;
if (hold_valid[j]) begin
selector = j;
break;
end
end
end
command_ready = hold_valid == 0;
for (int i = 0; i < `NUM_PDPS; ++i)
pdp_ready[i] = hold_valid == 0;
end
end
endmodule
|
