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replay_buffer: Fix 

If the lower bits of m_ptr is the same as s_ptr when we get s_axis_last
(that is, we are full), then we will immediately end (since m_ptr will
equal last_ptr). Fix this by including all of s_ptr in last_ptr.

Fixes: 52325f2 ("Add AXI stream replay buffer")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
This commit is contained in:
Sean Anderson 2022-12-24 23:46:35 -05:00
parent 040016bd44
commit 91ab3b40ce
1 changed files with 4 additions and 6 deletions
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10
rtl/axis_replay_buffer.v
View File

@ -9,8 +9,8 @@
* replayable will remain true until BUF_SIZE + 1 handshakes have occured * replayable will remain true until BUF_SIZE + 1 handshakes have occured
* without a replay. In particular, it is possible to restart a packet * without a replay. In particular, it is possible to restart a packet
* even after a handshake with m_axis_last set. To support this late replay * even after a handshake with m_axis_last set. To support this late replay
* feature, done must be asserted when the consumer is does not wish to * feature, done must be asserted when the consumer does not wish to perform
* perform any more replays. * any more replays.
* *
* In general, this buffer will add two cycles of latency. Additionally, there * In general, this buffer will add two cycles of latency. Additionally, there
* will may some latency when replayable goes low. This is because the slave * will may some latency when replayable goes low. This is because the slave
@ -67,8 +67,7 @@ module axis_replay_buffer (
reg m_axis_valid_next, m_axis_last_next; reg m_axis_valid_next, m_axis_last_next;
reg sent_last, sent_last_next; reg sent_last, sent_last_next;
reg [DATA_WIDTH - 1:0] buffer [(2 ** BUF_WIDTH) - 1:0]; reg [DATA_WIDTH - 1:0] buffer [(2 ** BUF_WIDTH) - 1:0];
reg [BUF_WIDTH:0] m_ptr, m_ptr_next, s_ptr, s_ptr_next; reg [BUF_WIDTH:0] m_ptr, m_ptr_next, s_ptr, s_ptr_next, last_ptr, last_ptr_next;
reg [BUF_WIDTH - 1:0] last_ptr, last_ptr_next;
reg [DATA_WIDTH - 1:0] s_data, m_data; reg [DATA_WIDTH - 1:0] s_data, m_data;
reg last, last_next; reg last, last_next;
reg full, empty, replayable_next, we, re; reg full, empty, replayable_next, we, re;
@ -113,7 +112,7 @@ module axis_replay_buffer (
/* read the next datum (if it's available)... */ /* read the next datum (if it's available)... */
m_axis_valid_next = !empty; m_axis_valid_next = !empty;
m_axis_last_next = last && m_ptr[BUF_WIDTH - 1:0] == last_ptr; m_axis_last_next = last && m_ptr == last_ptr;
re = !empty; re = !empty;
m_ptr_next = m_ptr + !empty; m_ptr_next = m_ptr + !empty;
/* ...except if we need to stall */ /* ...except if we need to stall */
@ -124,7 +123,6 @@ module axis_replay_buffer (
m_ptr_next = m_ptr; m_ptr_next = m_ptr;
end end
replayable_next = replayable; replayable_next = replayable;
sent_last_next = sent_last; sent_last_next = sent_last;
if (m_axis_valid && m_axis_ready) begin if (m_axis_valid && m_axis_ready) begin