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lfsr: Merge input 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 18:30:31 -07:00
parent a4ac9e7bb0
commit faa914c828
1 changed files with 53 additions and 14 deletions
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67
src/lfsr/rtl/taxi_lfsr.sv
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@@ -174,7 +174,12 @@ pcie Galois, bit-reverse 16 16'h0039 16'hffff PCIe
*/
localparam IN_W = LFSR_W+(DATA_IN_EN ? DATA_W : 0);
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 DATA_IN_INT = DATA_IN_EN && !INPUT_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);
function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
@@ -282,23 +287,35 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
if (REVERSE) begin
// output reversed
for (integer i = 0; i < LFSR_W; i = i + 1) begin
for (integer j = 0; j < LFSR_W; j = j + 1) begin
lfsr_mask[i][j] = lfsr_mask_state[LFSR_W-i-1][LFSR_W-j-1];
end
if (DATA_IN_EN) begin
if (INPUT_STATE_IN_DATA) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
lfsr_mask[i][j+LFSR_W] = lfsr_mask_data[LFSR_W-i-1][DATA_W-j-1];
lfsr_mask[i][j] = lfsr_mask_data[LFSR_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] = lfsr_mask_state[LFSR_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] = lfsr_mask_data[LFSR_W-i-1][DATA_W-j-1];
end
end
end
end
if (DATA_OUT_EN) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
for (integer j = 0; j < LFSR_W; j = j + 1) begin
lfsr_mask[i+LFSR_W][j] = output_mask_state[DATA_W-i-1][LFSR_W-j-1];
end
if (DATA_IN_EN) begin
if (INPUT_STATE_IN_DATA) begin
for (integer j = 0; j < DATA_W; j = j + 1) begin
lfsr_mask[i+LFSR_W][j+LFSR_W] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
lfsr_mask[i+LFSR_W][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+LFSR_W][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+LFSR_W][j+LFSR_W] = output_mask_data[DATA_W-i-1][DATA_W-j-1];
end
end
end
end
@@ -306,7 +323,9 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
end else begin
// output normal
for (integer i = 0; i < LFSR_W; i = i + 1) begin
if (DATA_IN_EN) begin
if (INPUT_STATE_IN_DATA) begin
lfsr_mask[i] = lfsr_mask_data[i];
end else if (DATA_IN_INT) begin
lfsr_mask[i] = {lfsr_mask_data[i], lfsr_mask_state[i]};
end else begin
lfsr_mask[i] = lfsr_mask_state[i];
@@ -314,7 +333,9 @@ function [OUT_W-1:0][IN_W-1:0] lfsr_mask();
end
if (DATA_OUT_EN) begin
for (integer i = 0; i < DATA_W; i = i + 1) begin
if (DATA_IN_EN) begin
if (INPUT_STATE_IN_DATA) begin
lfsr_mask[i+LFSR_W] = output_mask_data[i];
end else if (DATA_IN_INT) begin
lfsr_mask[i+LFSR_W] = {output_mask_data[i], output_mask_state[i]};
end else begin
lfsr_mask[i+LFSR_W] = output_mask_state[i];
@@ -331,7 +352,25 @@ wire [IN_W-1:0] lfsr_in;
wire [OUT_W-1:0] lfsr_out;
if (DATA_IN_EN) begin
assign lfsr_in = {data_in, state_in};
if (INPUT_STATE_IN_DATA) begin
if (DATA_W == LFSR_W) begin
assign lfsr_in = data_in ^ state_in;
end else begin
if (REVERSE) begin
assign lfsr_in = data_in ^ {{DATA_W - LFSR_W{1'b0}}, state_in};
end else begin
assign lfsr_in = data_in ^ {state_in, {DATA_W - LFSR_W{1'b0}}};
end
end
end else if (INPUT_DATA_IN_STATE) begin
if (REVERSE) begin
assign lfsr_in = {{LFSR_W - DATA_W{1'b0}}, data_in} ^ state_in;
end else begin
assign lfsr_in = {data_in, {LFSR_W - DATA_W{1'b0}}} ^ state_in;
end
end else begin
assign lfsr_in = {data_in, state_in};
end
end else begin
assign lfsr_in = state_in;
end