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lfsr: Merge output state with data when possible

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Signed-off-by: Alex Forencich <alex@alexforencich.com>
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Alex Forencich
2025-06-11 18:48:07 -07:00
parent faa914c828
commit a146aeaf21
1 changed files with 82 additions and 39 deletions
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49
src/lfsr/rtl/taxi_lfsr.sv
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@@ -176,11 +176,14 @@ pcie Galois, bit-reverse 16 16'h0039 16'hffff PCIe
localparam INPUT_DATA_IN_STATE = DATA_IN_EN && LFSR_GALOIS && !LFSR_FEED_FORWARD && DATA_W <= LFSR_W;
localparam INPUT_STATE_IN_DATA = DATA_IN_EN && LFSR_GALOIS && !LFSR_FEED_FORWARD && DATA_W > LFSR_W;
localparam OUTPUT_DATA_IN_STATE = DATA_OUT_EN && !LFSR_GALOIS && !LFSR_FEED_FORWARD && DATA_W <= LFSR_W;
localparam OUTPUT_STATE_IN_DATA = DATA_OUT_EN && !LFSR_GALOIS && !LFSR_FEED_FORWARD && DATA_W > LFSR_W;
localparam DATA_IN_INT = DATA_IN_EN && !INPUT_DATA_IN_STATE;
localparam DATA_OUT_INT = DATA_OUT_EN && !OUTPUT_DATA_IN_STATE;
localparam IN_W = INPUT_STATE_IN_DATA ? DATA_W : (LFSR_W+(DATA_IN_INT ? DATA_W : 0));
localparam OUT_W = LFSR_W+(DATA_OUT_EN ? DATA_W : 0);
localparam OUT_W = OUTPUT_STATE_IN_DATA ? DATA_W : (LFSR_W+(DATA_OUT_INT ? DATA_W : 0));
function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
logic [LFSR_W-1:0] lfsr_mask_state[LFSR_W-1:0];
@@ -286,6 +289,24 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
/* verilator lint_off WIDTH */
if (REVERSE) begin
// output reversed
if (OUTPUT_STATE_IN_DATA) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
lfsr_mask[i][j] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
end
end else begin
for (integer j = 0; j < LFSR_W; j = j + 1) begin
lfsr_mask[i][j] = output_mask_state[DATA_W-i-1][LFSR_W-j-1];
end
if (DATA_IN_INT) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
lfsr_mask[i][j+LFSR_W] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
end
end
end
end
end else begin
for (integer i = 0; i < LFSR_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
@@ -302,7 +323,7 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
end
end
end
if (DATA_OUT_EN) begin
if (DATA_OUT_INT) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
@@ -320,8 +341,21 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
end
end
end
end
end else begin
// output normal
if (OUTPUT_STATE_IN_DATA) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
lfsr_mask[i] = output_mask_data[i];
end else if (DATA_IN_INT) begin
lfsr_mask[i] = {output_mask_data[i], output_mask_state[i]};
end else begin
lfsr_mask[i] = output_mask_state[i];
end
end
end else begin
for (integer i = 0; i < LFSR_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
lfsr_mask[i] = lfsr_mask_data[i];
@@ -331,7 +365,7 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
lfsr_mask[i] = lfsr_mask_state[i];
end
end
if (DATA_OUT_EN) begin
if (DATA_OUT_INT) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
if (INPUT_STATE_IN_DATA) begin
lfsr_mask[i+LFSR_W] = output_mask_data[i];
@@ -343,6 +377,7 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
end
end
end
end
/* verilator lint_on WIDTH */
endfunction
@@ -379,6 +414,13 @@ for (genvar n = 0; n < OUT_W; n = n + 1) begin
assign lfsr_out[n] = ^(lfsr_in & mask[n]);
end
if (OUTPUT_DATA_IN_STATE) begin
assign state_out = lfsr_out;
assign data_out = REVERSE ? lfsr_out[OUT_W-1 -: DATA_W] : lfsr_out[0 +: DATA_W];
end else if (OUTPUT_STATE_IN_DATA) begin
assign state_out = REVERSE ? lfsr_out[OUT_W-1 -: LFSR_W] : lfsr_out[0 +: LFSR_W];
assign data_out = lfsr_out;
end else begin
assign state_out = lfsr_out[0 +: LFSR_W];
if (DATA_OUT_EN) begin
@@ -386,6 +428,7 @@ if (DATA_OUT_EN) begin
end else begin
assign data_out = '0;
end
end
endmodule