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Konstantin Pavlov 2023-05-23 11:30:21 +03:00
parent 0475ea0398
commit f0edcd3af0
1 changed files with 65 additions and 61 deletions
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126
lifo.sv
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@ -47,8 +47,6 @@ module lifo #( parameter
// "FALSE" - normal fifo mode
DEPTH = 8, // max elements count == DEPTH, DEPTH MUST be power of 2
DEPTH_W = $clog2(DEPTH)+1, // elements counter width, extra bit to store
// "fifo full" state, see cnt[] variable comments
DATA_W = 32 // data field width
)(
@ -72,76 +70,82 @@ module lifo #( parameter
output logic fail
);
// lifo data
logic [DEPTH-1:0][DATA_W-1:0] data = '0;
// data output buffer for normal fifo mode
logic [DATA_W-1:0] data_buf = '0;
// cnt[] vector always holds lifo elements count
// data[cnt[]] points to the first empty lifo slot
// when lifo is full data[cnt[]] points "outside" of data[]
// filtered requests
logic w_req_f;
assign w_req_f = w_req && ~full;
logic r_req_f;
assign r_req_f = r_req && ~empty;
// elements counter width, extra bit to store
// "fifo full" state, see cnt[] variable comments
localparam DEPTH_W = $clog2(DEPTH+1);
integer i;
always_ff @(posedge clk) begin
if ( ~nrst ) begin
data <= '0;
cnt[DEPTH_W-1:0] <= '0;
data_buf[DATA_W-1:0] <= '0;
end else begin
unique case ({w_req_f, r_req_f})
2'b00: ; // nothing
// lifo data
logic [DEPTH-1:0][DATA_W-1:0] data = '0;
2'b01 : begin // reading out
for ( i = (DEPTH-1); i > 0; i-- ) begin
data[i-1] <= data[i];
end
cnt[DEPTH_W-1:0] <= cnt[DEPTH_W-1:0] - 1'b1;
end
// data output buffer for normal fifo mode
logic [DATA_W-1:0] data_buf = '0;
2'b10 : begin // writing in
data[cnt[DEPTH_W-1:0]] <= w_data[DATA_W-1:0];
cnt[DEPTH_W-1:0] <= cnt[DEPTH_W-1:0] + 1'b1;
end
// cnt[] vector always holds lifo elements count
// data[cnt[]] points to the first empty lifo slot
// when lifo is full data[cnt[]] points "outside" of data[]
2'b11 : begin // simultaneously reading and writing
data[cnt[DEPTH_W-1:0]-1] <= w_data[DATA_W-1:0];
// data counter does not change here
end
endcase
// filtered requests
logic w_req_f;
assign w_req_f = w_req && ~full;
// data buffer works only for normal lifo mode
if( r_req_f ) begin
data_buf[DATA_W-1:0] <= data[0];
end
end
end
logic r_req_f;
assign r_req_f = r_req && ~empty;
always_comb begin
empty = ( cnt[DEPTH_W-1:0] == '0 );
full = ( cnt[DEPTH_W-1:0] == DEPTH );
if( FWFT_MODE == "TRUE" ) begin
if (~empty) begin
r_data[DATA_W-1:0] = data[0]; // first-word fall-through mode
integer i;
always_ff @(posedge clk) begin
if ( ~nrst ) begin
data <= '0;
cnt[DEPTH_W-1:0] <= '0;
data_buf[DATA_W-1:0] <= '0;
end else begin
r_data[DATA_W-1:0] = '0;
unique case ({w_req_f, r_req_f})
2'b00: ; // nothing
2'b01 : begin // reading out
for ( i = (DEPTH-1); i > 0; i-- ) begin
data[i-1] <= data[i];
end
cnt[DEPTH_W-1:0] <= cnt[DEPTH_W-1:0] - 1'b1;
end
2'b10 : begin // writing in
data[cnt[DEPTH_W-1:0]] <= w_data[DATA_W-1:0];
cnt[DEPTH_W-1:0] <= cnt[DEPTH_W-1:0] + 1'b1;
end
2'b11 : begin // simultaneously reading and writing
data[cnt[DEPTH_W-1:0]-1] <= w_data[DATA_W-1:0];
// data counter does not change here
end
endcase
// data buffer works only for normal lifo mode
if( r_req_f ) begin
data_buf[DATA_W-1:0] <= data[0];
end
end
end else begin
r_data[DATA_W-1:0] = data_buf[DATA_W-1:0]; // normal mode
end
fail = ( empty && r_req ) ||
( full && w_req );
end
always_comb begin
empty = ( cnt[DEPTH_W-1:0] == '0 );
full = ( cnt[DEPTH_W-1:0] == DEPTH );
if( FWFT_MODE == "TRUE" ) begin
if (~empty) begin
r_data[DATA_W-1:0] = data[0]; // first-word fall-through mode
end else begin
r_data[DATA_W-1:0] = '0;
end
end else begin
r_data[DATA_W-1:0] = data_buf[DATA_W-1:0]; // normal mode
end
fail = ( empty && r_req ) ||
( full && w_req );
end
endmodule