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Improve detection of empty and full FIFO

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Joachim Strömbergson 2022-10-28 13:09:21 +02:00
parent 0eacbca2f9
commit 24d8680772
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GPG Key ID: 865B8A548EA61679
1 changed files with 24 additions and 4 deletions
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28
hw/application_fpga/core/uart/rtl/uart_fifo.v
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@ -3,6 +3,7 @@
// uart_fifo.v
// -----------
// FIFO for rx and tx data buffering in the UART.
// The code should allocate a single EBR in a iCE40UP device.
//
//
// Author: Joachim Strombergson
@ -73,6 +74,13 @@ module uart_fifo(
reg in_ack_new;
//----------------------------------------------------------------
// Wires
//----------------------------------------------------------------
reg fifo_empty;
reg fifo_full;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
@ -120,9 +128,19 @@ module uart_fifo(
//----------------------------------------------------------------
always @*
begin : byte_ctr
fifo_empty = 1'h0;
fifo_full = 1'h0;
byte_ctr_new = 9'h0;
byte_ctr_we = 1'h0;
if (byte_ctr_reg == 9'h0) begin
fifo_empty = 1'h1;
end
if (byte_ctr_reg == 9'h1ff) begin
fifo_full = 1'h1;
end
if ((byte_ctr_inc) && (!byte_ctr_dec)) begin
byte_ctr_new = byte_ctr_reg + 1'h1;
byte_ctr_we = 1'h1;
@ -143,10 +161,11 @@ module uart_fifo(
fifo_mem_we = 1'h0;
in_ack_new = 1'h0;
byte_ctr_inc = 1'h0;
in_ptr_new = in_ptr_reg + 1'h1;
in_ptr_we = 1'h0;
if ((in_syn) && (!in_ack) && (byte_ctr_reg < 9'h1ff)) begin
in_ptr_new = in_ptr_reg + 1'h1;
if ((in_syn) && (!in_ack) && (!fifo_full)) begin
fifo_mem_we = 1'h1;
in_ack_new = 1'h1;
byte_ctr_inc = 1'h1;
@ -161,10 +180,11 @@ module uart_fifo(
always @*
begin : out_logic
byte_ctr_dec = 1'h0;
out_ptr_new = out_ptr_reg + 1'h1;
out_ptr_we = 1'h0;
if ((out_ack) && (byte_ctr_reg > 9'h0)) begin
out_ptr_new = out_ptr_reg + 1'h1;
if ((out_ack) && (!fifo_empty)) begin
byte_ctr_dec = 1'h1;
out_ptr_we = 1'h1;
end