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Fix frame FIFO full logic bug

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This commit is contained in:
Alex Forencich 2018-12-09 00:01:38 -08:00
parent f9a5e6803b
commit 3d90e80da8
2 changed files with 76 additions and 70 deletions
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79
rtl/axis_async_fifo.v
View File

@ -124,6 +124,7 @@ localparam WIDTH = USER_OFFSET + (USER_ENABLE ? USER_WIDTH : 0);
reg [ADDR_WIDTH:0] wr_ptr_reg = {ADDR_WIDTH+1{1'b0}}, wr_ptr_next;
reg [ADDR_WIDTH:0] wr_ptr_cur_reg = {ADDR_WIDTH+1{1'b0}}, wr_ptr_cur_next;
reg [ADDR_WIDTH:0] wr_ptr_gray_reg = {ADDR_WIDTH+1{1'b0}}, wr_ptr_gray_next;
reg [ADDR_WIDTH:0] wr_ptr_cur_gray_reg = {ADDR_WIDTH+1{1'b0}}, wr_ptr_cur_gray_next;
reg [ADDR_WIDTH:0] wr_addr_reg = {ADDR_WIDTH+1{1'b0}};
reg [ADDR_WIDTH:0] rd_ptr_reg = {ADDR_WIDTH+1{1'b0}}, rd_ptr_next;
reg [ADDR_WIDTH:0] rd_ptr_gray_reg = {ADDR_WIDTH+1{1'b0}}, rd_ptr_gray_next;
@ -155,11 +156,14 @@ reg m_axis_tvalid_reg = 1'b0, m_axis_tvalid_next;
wire full = ((wr_ptr_gray_reg[ADDR_WIDTH] != rd_ptr_gray_sync2_reg[ADDR_WIDTH]) &&
(wr_ptr_gray_reg[ADDR_WIDTH-1] != rd_ptr_gray_sync2_reg[ADDR_WIDTH-1]) &&
(wr_ptr_gray_reg[ADDR_WIDTH-2:0] == rd_ptr_gray_sync2_reg[ADDR_WIDTH-2:0]));
wire full_cur = ((wr_ptr_cur_gray_reg[ADDR_WIDTH] != rd_ptr_gray_sync2_reg[ADDR_WIDTH]) &&
(wr_ptr_cur_gray_reg[ADDR_WIDTH-1] != rd_ptr_gray_sync2_reg[ADDR_WIDTH-1]) &&
(wr_ptr_cur_gray_reg[ADDR_WIDTH-2:0] == rd_ptr_gray_sync2_reg[ADDR_WIDTH-2:0]));
// empty when pointers match exactly
wire empty = rd_ptr_gray_reg == wr_ptr_gray_sync2_reg;
// overflow within packet
wire full_cur = ((wr_ptr_reg[ADDR_WIDTH] != wr_ptr_cur_reg[ADDR_WIDTH]) &&
(wr_ptr_reg[ADDR_WIDTH-1:0] == wr_ptr_cur_reg[ADDR_WIDTH-1:0]));
wire full_wr = ((wr_ptr_reg[ADDR_WIDTH] != wr_ptr_cur_reg[ADDR_WIDTH]) &&
(wr_ptr_reg[ADDR_WIDTH-1:0] == wr_ptr_cur_reg[ADDR_WIDTH-1:0]));
// control signals
reg write;
@ -184,7 +188,7 @@ reg good_frame_sync2_reg = 1'b0;
reg good_frame_sync3_reg = 1'b0;
reg good_frame_sync4_reg = 1'b0;
assign s_axis_tready = (!full || DROP_WHEN_FULL) && !s_rst_sync3_reg;
assign s_axis_tready = (FRAME_FIFO ? (!full_cur || full_wr || DROP_WHEN_FULL) : !full) && !s_rst_sync3_reg;
generate
assign s_axis[DATA_WIDTH-1:0] = s_axis_tdata;
@ -249,41 +253,42 @@ always @* begin
wr_ptr_next = wr_ptr_reg;
wr_ptr_cur_next = wr_ptr_cur_reg;
wr_ptr_gray_next = wr_ptr_gray_reg;
wr_ptr_cur_gray_next = wr_ptr_cur_gray_reg;
if (s_axis_tvalid) begin
// input data valid
if (!full || DROP_WHEN_FULL) begin
// not full, perform write
if (!FRAME_FIFO) begin
// normal FIFO mode
write = 1'b1;
wr_ptr_next = wr_ptr_reg + 1;
wr_ptr_gray_next = wr_ptr_next ^ (wr_ptr_next >> 1);
end else if (full || full_cur || drop_frame_reg) begin
// full, packet overflow, or currently dropping frame
// drop frame
drop_frame_next = 1'b1;
if (s_axis_tlast) begin
// end of frame, reset write pointer
if (s_axis_tready && s_axis_tvalid) begin
// transfer in
if (!FRAME_FIFO) begin
// normal FIFO mode
write = 1'b1;
wr_ptr_next = wr_ptr_reg + 1;
wr_ptr_gray_next = wr_ptr_next ^ (wr_ptr_next >> 1);
end else if (full_cur || full_wr || drop_frame_reg) begin
// full, packet overflow, or currently dropping frame
// drop frame
drop_frame_next = 1'b1;
if (s_axis_tlast) begin
// end of frame, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
wr_ptr_cur_gray_next = wr_ptr_cur_next ^ (wr_ptr_cur_next >> 1);
drop_frame_next = 1'b0;
overflow_next = 1'b1;
end
end else begin
write = 1'b1;
wr_ptr_cur_next = wr_ptr_cur_reg + 1;
wr_ptr_cur_gray_next = wr_ptr_cur_next ^ (wr_ptr_cur_next >> 1);
if (s_axis_tlast) begin
// end of frame
if (DROP_BAD_FRAME && (USER_BAD_FRAME_MASK & s_axis_tuser == USER_BAD_FRAME_VALUE)) begin
// bad packet, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
drop_frame_next = 1'b0;
overflow_next = 1'b1;
end
end else begin
write = 1'b1;
wr_ptr_cur_next = wr_ptr_cur_reg + 1;
if (s_axis_tlast) begin
// end of frame
if (DROP_BAD_FRAME && (USER_BAD_FRAME_MASK & s_axis_tuser == USER_BAD_FRAME_VALUE)) begin
// bad packet, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
bad_frame_next = 1'b1;
end else begin
// good packet, update write pointer
wr_ptr_next = wr_ptr_cur_reg + 1;
wr_ptr_gray_next = wr_ptr_next ^ (wr_ptr_next >> 1);
good_frame_next = 1'b1;
end
wr_ptr_cur_gray_next = wr_ptr_cur_next ^ (wr_ptr_cur_next >> 1);
bad_frame_next = 1'b1;
end else begin
// good packet, update write pointer
wr_ptr_next = wr_ptr_cur_reg + 1;
wr_ptr_gray_next = wr_ptr_next ^ (wr_ptr_next >> 1);
good_frame_next = 1'b1;
end
end
end
@ -295,6 +300,7 @@ always @(posedge s_clk) begin
wr_ptr_reg <= {ADDR_WIDTH+1{1'b0}};
wr_ptr_cur_reg <= {ADDR_WIDTH+1{1'b0}};
wr_ptr_gray_reg <= {ADDR_WIDTH+1{1'b0}};
wr_ptr_cur_gray_reg <= {ADDR_WIDTH+1{1'b0}};
drop_frame_reg <= 1'b0;
overflow_reg <= 1'b0;
@ -304,6 +310,7 @@ always @(posedge s_clk) begin
wr_ptr_reg <= wr_ptr_next;
wr_ptr_cur_reg <= wr_ptr_cur_next;
wr_ptr_gray_reg <= wr_ptr_gray_next;
wr_ptr_cur_gray_reg <= wr_ptr_cur_gray_next;
drop_frame_reg <= drop_frame_next;
overflow_reg <= overflow_next;

67
rtl/axis_fifo.v
View File

@ -132,11 +132,13 @@ reg m_axis_tvalid_reg = 1'b0, m_axis_tvalid_next;
// full when first MSB different but rest same
wire full = ((wr_ptr_reg[ADDR_WIDTH] != rd_ptr_reg[ADDR_WIDTH]) &&
(wr_ptr_reg[ADDR_WIDTH-1:0] == rd_ptr_reg[ADDR_WIDTH-1:0]));
wire full_cur = ((wr_ptr_cur_reg[ADDR_WIDTH] != rd_ptr_reg[ADDR_WIDTH]) &&
(wr_ptr_cur_reg[ADDR_WIDTH-1:0] == rd_ptr_reg[ADDR_WIDTH-1:0]));
// empty when pointers match exactly
wire empty = wr_ptr_reg == rd_ptr_reg;
// overflow within packet
wire full_cur = ((wr_ptr_reg[ADDR_WIDTH] != wr_ptr_cur_reg[ADDR_WIDTH]) &&
(wr_ptr_reg[ADDR_WIDTH-1:0] == wr_ptr_cur_reg[ADDR_WIDTH-1:0]));
wire full_wr = ((wr_ptr_reg[ADDR_WIDTH] != wr_ptr_cur_reg[ADDR_WIDTH]) &&
(wr_ptr_reg[ADDR_WIDTH-1:0] == wr_ptr_cur_reg[ADDR_WIDTH-1:0]));
// control signals
reg write;
@ -148,7 +150,7 @@ reg overflow_reg = 1'b0, overflow_next;
reg bad_frame_reg = 1'b0, bad_frame_next;
reg good_frame_reg = 1'b0, good_frame_next;
assign s_axis_tready = (!full || DROP_WHEN_FULL);
assign s_axis_tready = FRAME_FIFO ? (!full_cur || full_wr || DROP_WHEN_FULL) : !full;
generate
assign s_axis[DATA_WIDTH-1:0] = s_axis_tdata;
@ -184,38 +186,35 @@ always @* begin
wr_ptr_next = wr_ptr_reg;
wr_ptr_cur_next = wr_ptr_cur_reg;
if (s_axis_tvalid) begin
// input data valid
if (!full || DROP_WHEN_FULL) begin
// not full, perform write
if (!FRAME_FIFO) begin
// normal FIFO mode
write = 1'b1;
wr_ptr_next = wr_ptr_reg + 1;
end else if (full || full_cur || drop_frame_reg) begin
// full, packet overflow, or currently dropping frame
// drop frame
drop_frame_next = 1'b1;
if (s_axis_tlast) begin
// end of frame, reset write pointer
if (s_axis_tready && s_axis_tvalid) begin
// transfer in
if (!FRAME_FIFO) begin
// normal FIFO mode
write = 1'b1;
wr_ptr_next = wr_ptr_reg + 1;
end else if (full_cur || full_wr || drop_frame_reg) begin
// full, packet overflow, or currently dropping frame
// drop frame
drop_frame_next = 1'b1;
if (s_axis_tlast) begin
// end of frame, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
drop_frame_next = 1'b0;
overflow_next = 1'b1;
end
end else begin
write = 1'b1;
wr_ptr_cur_next = wr_ptr_cur_reg + 1;
if (s_axis_tlast) begin
// end of frame
if (DROP_BAD_FRAME && (USER_BAD_FRAME_MASK & s_axis_tuser == USER_BAD_FRAME_VALUE)) begin
// bad packet, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
drop_frame_next = 1'b0;
overflow_next = 1'b1;
end
end else begin
write = 1'b1;
wr_ptr_cur_next = wr_ptr_cur_reg + 1;
if (s_axis_tlast) begin
// end of frame
if (DROP_BAD_FRAME && (USER_BAD_FRAME_MASK & s_axis_tuser == USER_BAD_FRAME_VALUE)) begin
// bad packet, reset write pointer
wr_ptr_cur_next = wr_ptr_reg;
bad_frame_next = 1'b1;
end else begin
// good packet, update write pointer
wr_ptr_next = wr_ptr_cur_reg + 1;
good_frame_next = 1'b1;
end
bad_frame_next = 1'b1;
end else begin
// good packet, update write pointer
wr_ptr_next = wr_ptr_cur_reg + 1;
good_frame_next = 1'b1;
end
end
end