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UberDDR3/delete_later/rtl/net/netfifo.v

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////////////////////////////////////////////////////////////////////////////////
//
// Filename: netfifo.v
// {{{
// Project: 10Gb Ethernet switch
//
// Purpose: Abortable packet FIFO. Does not include native support for the
// BYTES field, however the data field can be expanded for this
// purpose.
//
// Creator: Dan Gisselquist, Ph.D.
// Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
// }}}
// Copyright (C) 2023, Gisselquist Technology, LLC
// {{{
// This file is part of the ETH10G project.
//
// The ETH10G project contains free software and gateware, licensed under the
// Apache License, Version 2.0 (the "License"). You may not use this project,
// or this file, except in compliance with the License. You may obtain a copy
// of the License at
// }}}
// http://www.apache.org/licenses/LICENSE-2.0
// {{{
// Unless required by applicable law or agreed to in writing, files
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
//
////////////////////////////////////////////////////////////////////////////////
//
`default_nettype none
// }}}
module netfifo #(
// {{{
parameter BW=8, // Byte/data width
parameter LGFLEN=4,
parameter [0:0] OPT_ASYNC_READ = 1'b1,
parameter [0:0] OPT_WRITE_ON_FULL = 1'b0,
parameter [0:0] OPT_READ_ON_EMPTY = 1'b0,
localparam FLEN=(1<<LGFLEN)
// }}}
) (
// {{{
input wire S_AXI_ACLK,
input wire S_AXI_ARESETN,
//
// Write interface
input wire S_AXIN_VALID,
output reg S_AXIN_READY,
input wire [BW-1:0] S_AXIN_DATA,
input wire S_AXIN_LAST,
input wire S_AXIN_ABORT,
//
// Read interface
output reg M_AXIN_VALID,
input wire M_AXIN_READY,
output reg [BW-1:0] M_AXIN_DATA,
output reg M_AXIN_LAST,
output reg M_AXIN_ABORT
// }}}
);
// Register/net declarations
// {{{
reg lastv;
wire r_full, eop_next, r_empty;
reg [BW:0] mem [0:(FLEN-1)];
reg [LGFLEN:0] wr_addr, rd_addr, eop_addr;
wire [LGFLEN:0] fill;
reg r_midpacket, s_midpacket;
wire w_wr = (S_AXIN_VALID && S_AXIN_READY && !S_AXIN_ABORT);
wire w_rd = (M_AXIN_VALID && M_AXIN_READY); //
// || (!M_AXIN_LAST && M_AXIN_ABORT && fill > (1+s_abort))));
wire s_abort = S_AXIN_ABORT && s_midpacket;
// wire w_abort = lastv && S_AXIN_ABORT;
// }}}
// fill
// {{{
assign fill = wr_addr - rd_addr;
// }}}
// r_full
// {{{
assign r_full = fill[LGFLEN];
// }}}
// S_AXIN_READY
// {{{
always @(*)
if (OPT_WRITE_ON_FULL && M_AXIN_READY)
S_AXIN_READY = 1'b1;
else if (S_AXIN_ABORT)
S_AXIN_READY = 1'b1;
else
S_AXIN_READY = !r_full;
// }}}
// lastv
// {{{
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
lastv <= 0; // End of packet pointer is invalid
else if (S_AXIN_VALID && S_AXIN_READY && !S_AXIN_ABORT && S_AXIN_LAST
&& (!r_empty || !M_AXIN_READY))
lastv <= 1; // EOP points to valid spot in the FIFO
else if (w_rd && eop_next)
lastv <= 0; // Packet was read, EOP is now invalid
// }}}
// eop_addr
// {{{
initial eop_addr = 0;
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
eop_addr <= 0;
else if (S_AXIN_VALID && S_AXIN_READY && !S_AXIN_ABORT && S_AXIN_LAST)
eop_addr <= wr_addr;
// }}}
// eop_next
// {{{
assign eop_next = lastv && (eop_addr == rd_addr);
// }}}
// wr_addr, the write address pointer
// {{{
initial wr_addr = 0;
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
wr_addr <= 0;
else if (s_abort)
begin
if (lastv)
wr_addr <= eop_addr + 1; // Back up to last pkt
else if (M_AXIN_VALID)
wr_addr <= rd_addr + 1; // Empty FIFO, no pkts within it
end else if (w_wr)
wr_addr <= wr_addr + 1'b1;
// }}}
// Write to memory
// {{{
always @(posedge S_AXI_ACLK)
if (w_wr)
mem[wr_addr[(LGFLEN-1):0]] <= { S_AXIN_LAST, S_AXIN_DATA };
// }}}
// rd_addr, the read address pointer
// {{{
initial rd_addr = 0;
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
rd_addr <= 0;
else if (w_rd)
rd_addr <= rd_addr + 1;
// }}}
// r_empty
// {{{
assign r_empty = (wr_addr == rd_addr);
// }}}
// M_AXIN_VALID
// {{{
always @(*)
if (OPT_READ_ON_EMPTY && S_AXIN_VALID && !S_AXIN_ABORT)
M_AXIN_VALID = 1'b1;
else
M_AXIN_VALID = !r_empty;
// }}}
// M_AXIN_LAST, M_AXIN_DATA: Read from the FIFO
// {{{
generate if (OPT_ASYNC_READ && OPT_READ_ON_EMPTY)
begin : ASYNCHRONOUS_READ_ON_EMPTY
// M_AXIN_LAST, M_AXIN_DATA
// {{{
reg r_last, last_override;
always @(*)
begin
{ r_last, M_AXIN_DATA } = mem[rd_addr[LGFLEN-1:0]];
if (r_empty)
{ r_last, M_AXIN_DATA } = { S_AXIN_LAST, S_AXIN_DATA };
end
always @(posedge S_AXI_ACLK)
last_override <= 0 && (M_AXIN_VALID && !M_AXIN_READY && M_AXIN_LAST);
always @(*)
M_AXIN_LAST = r_last || last_override;
// }}}
end else if (OPT_ASYNC_READ)
begin : ASYNCHRONOUS_READ
// M_AXIN_LAST, M_AXIN_DATA
// {{{
always @(*)
{ M_AXIN_LAST, M_AXIN_DATA } = mem[rd_addr[LGFLEN-1:0]];
// }}}
end else begin : REGISTERED_READ
// {{{
reg bypass_valid;
reg [BW:0] bypass_data, rd_data;
reg [LGFLEN-1:0] rd_next;
always @(*)
rd_next = rd_addr[LGFLEN-1:0] + 1;
// Memory read, bypassing it if we must
// {{{
initial bypass_valid = 0;
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
bypass_valid <= 0;
else begin
bypass_valid <= 1'b0;
if (S_AXIN_VALID
&& (r_empty || (M_AXIN_READY && (fill == 1))))
bypass_valid <= 1'b1;
if (s_abort && !lastv)
bypass_valid <= 1'b1;
end
always @(posedge S_AXI_ACLK)
bypass_data <= { (S_AXIN_LAST || S_AXIN_ABORT), S_AXIN_DATA };
initial mem[0] = 0;
initial rd_data = 0;
always @(posedge S_AXI_ACLK)
if (bypass_valid || w_rd)
// (!M_AXIN_VALID || M_AXIN_READY || (M_AXIN_ABORT && !M_AXIN_LAST)))
rd_data <= mem[(w_rd)?rd_next : rd_addr[LGFLEN-1:0]];
always @(*)
if (OPT_READ_ON_EMPTY && r_empty)
{ M_AXIN_LAST, M_AXIN_DATA } = { S_AXIN_LAST, S_AXIN_DATA };
else if (bypass_valid)
{ M_AXIN_LAST, M_AXIN_DATA } = bypass_data;
else
{ M_AXIN_LAST, M_AXIN_DATA } = rd_data;
// }}}
// }}}
end endgenerate
// }}}
// M_AXIN_ABORT
// {{{
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
r_midpacket <= 0;
else if (M_AXIN_VALID)
r_midpacket <= (!M_AXIN_READY || !M_AXIN_LAST);
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
s_midpacket <= 0;
else if (S_AXIN_ABORT)
s_midpacket <= 0;
else if (S_AXIN_VALID && S_AXIN_READY)
s_midpacket <= !S_AXIN_LAST;
always @(posedge S_AXI_ACLK)
if (!S_AXI_ARESETN)
M_AXIN_ABORT <= 1'b0;
else if (!M_AXIN_ABORT)
begin
if (!lastv)
M_AXIN_ABORT <= S_AXIN_ABORT && (M_AXIN_VALID || r_midpacket) && s_midpacket;
end else if (!M_AXIN_VALID || M_AXIN_READY)
M_AXIN_ABORT <= 1'b0;
// }}}
// Make Verilator happy
// {{{
// verilator lint_off UNUSED
wire unused;
assign unused = &{ 1'b0, fill, r_empty };
// verilator lint_on UNUSED
// }}}
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
//
// FORMAL METHODS
// {{{
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////
//
`ifdef FORMAL
//
// Assumptions about our input(s)
//
//
`ifdef SFIFO
`define ASSUME assume
`else
`define ASSUME assert
`endif
reg f_past_valid;
wire [LGFLEN:0] f_fill, f_next;
wire f_full, f_empty;
initial f_past_valid = 1'b0;
always @(posedge S_AXI_ACLK)
f_past_valid <= 1'b1;
////////////////////////////////////////////////////////////////////////
//
// Interface properties
// {{{
////////////////////////////////////////////////////////////////////////
//
//
wire [9:0] faxin_swords, faxin_mwords;
wire [11:0] faxin_spkts, faxin_mpkts;
faxin_slave #(
// {{{
.DATA_WIDTH(BW),
.MIN_LENGTH(0)
// }}}
) faxins (
// {{{
.S_AXI_ACLK(S_AXI_ACLK), .S_AXI_ARESETN(S_AXI_ARESETN),
//
.S_AXIN_VALID(S_AXIN_VALID), .S_AXIN_READY(S_AXIN_READY),
.S_AXIN_DATA(S_AXIN_DATA), .S_AXIN_LAST(S_AXIN_LAST),
.S_AXIN_ABORT(S_AXIN_ABORT),
//
.f_stream_word(faxin_swords),
.f_packets_rcvd(faxin_spkts)
// }}}
);
faxin_master #(
// {{{
.DATA_WIDTH(BW),
.MIN_LENGTH(0), .MAX_LENGTH(0)
// }}}
) faxinm (
// {{{
.S_AXI_ACLK(S_AXI_ACLK), .S_AXI_ARESETN(S_AXI_ARESETN),
//
.S_AXIN_VALID(M_AXIN_VALID), .S_AXIN_READY(M_AXIN_READY),
.S_AXIN_DATA(M_AXIN_DATA), .S_AXIN_LAST(M_AXIN_LAST),
.S_AXIN_ABORT(M_AXIN_ABORT),
//
.f_stream_word(faxin_mwords),
.f_packets_rcvd(faxin_mpkts)
// }}}
);
// }}}
////////////////////////////////////////////////////////////////////////
//
// Assertions about our flags and counters
// {{{
////////////////////////////////////////////////////////////////////////
//
//
assign f_fill = wr_addr - rd_addr;
assign f_empty = (wr_addr == rd_addr);
assign f_full = (f_fill >= (1<<LGFLEN));
assign f_next = rd_addr + 1'b1;
// fill, S_AXIN_READY, M_AXIN_READY, and r_empty
// {{{
always @(*)
begin
assert(f_fill <= { 1'b1, {(LGFLEN){1'b0}} });
assert(fill == f_fill);
assert(r_full == (f_fill == {1'b1, {(LGFLEN){1'b0}} }));
assert(r_empty == (f_fill == 0));
// assert(rd_next == f_next[LGFLEN-1:0]);
if (!OPT_WRITE_ON_FULL)
begin
assert(S_AXIN_READY == (!f_full || S_AXIN_ABORT));
end else
assert(S_AXIN_READY == (!r_full || S_AXIN_ABORT || M_AXIN_READY));
if (!OPT_READ_ON_EMPTY)
begin
assert(M_AXIN_VALID == !r_empty);
end else
assert(M_AXIN_VALID == !r_empty || (S_AXIN_VALID && !S_AXIN_ABORT));
end
// }}}
always @(posedge S_AXI_ACLK)
if (!OPT_ASYNC_READ && f_past_valid && f_fill == 0)
begin
assert(!M_AXIN_VALID || (OPT_READ_ON_EMPTY && S_AXIN_VALID));
end
always @(*)
if (rd_addr != wr_addr)
begin
// This also applies for the registered read case
assert(M_AXIN_ABORT || mem[rd_addr[LGFLEN-1:0]] == { M_AXIN_LAST, M_AXIN_DATA });
end else if (OPT_READ_ON_EMPTY)
begin
assert(!S_AXIN_LAST || M_AXIN_LAST);
assert(M_AXIN_DATA == S_AXIN_DATA);
end
// }}}
////////////////////////////////////////////////////////////////////////
//
// Formal contract: (Twin write test)
// {{{
// If you write two values in succession, you should be able to read
// those same two values in succession some time later.
//
////////////////////////////////////////////////////////////////////////
//
//
// Verilator lint_off UNDRIVEN
(* anyconst *) reg [LGFLEN:0] f_first_addr;
// Verilator lint_on UNDRIVEN
reg [LGFLEN:0] f_second_addr;
reg [BW:0] f_first_data, f_second_data, f_eop_data;
reg f_first_addr_in_fifo, f_first_in_fifo;
reg f_second_addr_in_fifo, f_second_in_fifo;
reg f_eop_addr_in_fifo;
reg [LGFLEN:0] f_distance_to_first, f_distance_to_second,
f_distance_to_eop,
f_first_to_eop, f_second_to_eop;
always @(*)
f_second_addr = f_first_addr + 1;
// f_distance_to_first, f_first_addr_in_fifo
// {{{
always @(*)
begin
f_distance_to_first = (f_first_addr - rd_addr);
f_first_addr_in_fifo = 0;
if ((f_fill != 0) && (f_distance_to_first < f_fill))
f_first_addr_in_fifo = 1;
end
// }}}
// f_distance_to_second, f_second_addr_in_fifo
// {{{
always @(*)
begin
f_distance_to_second = (f_second_addr - rd_addr);
f_second_addr_in_fifo = 0;
if ((f_fill != 0) && (f_distance_to_second < f_fill))
f_second_addr_in_fifo = 1;
end
// }}}
// f_distance_to_eop, f_eop_addr_in_fifo
// {{{
always @(*)
begin
f_distance_to_eop = (eop_addr - rd_addr);
f_eop_addr_in_fifo = 0;
if ((f_fill != 0) && (f_distance_to_eop < f_fill))
f_eop_addr_in_fifo = 1;
end
// }}}
// f_first_data
// {{{
always @(posedge S_AXI_ACLK)
if (w_wr && wr_addr == f_first_addr)
f_first_data <= { S_AXIN_LAST, S_AXIN_DATA };
// }}}
// f_second_data
// {{{
always @(posedge S_AXI_ACLK)
if (w_wr && wr_addr == f_second_addr)
f_second_data <= { S_AXIN_LAST, S_AXIN_DATA };
// }}}
// f_first_data checks
// {{{
always @(*)
if (f_first_addr_in_fifo)
assert(mem[f_first_addr[LGFLEN-1:0]] == f_first_data);
always @(*)
if (f_first_addr_in_fifo && lastv && f_first_addr == eop_addr)
assert(mem[f_first_addr[LGFLEN-1:0]][BW]);
always @(*)
f_first_in_fifo = (f_first_addr_in_fifo && (mem[f_first_addr[LGFLEN-1:0]] == f_first_data));
// }}}
// f_second_data checks
// {{{
always @(*)
if (f_second_addr_in_fifo)
assert(mem[f_second_addr[LGFLEN-1:0]] == f_second_data);
always @(*)
if (f_second_addr_in_fifo && lastv && f_second_addr == eop_addr)
assert(mem[f_second_addr[LGFLEN-1:0]][BW]);
always @(*)
f_second_in_fifo = (f_second_addr_in_fifo && (mem[f_second_addr[LGFLEN-1:0]] == f_second_data));
// }}}
// EOP checks
// {{{
always @(*)
f_first_to_eop = (eop_addr - f_first_addr);
always @(*)
f_second_to_eop = (eop_addr - f_second_addr);
always @(*)
f_eop_data = mem[eop_addr[LGFLEN-1:0]];
always @(*)
if (S_AXI_ARESETN && lastv)
begin
assert(f_eop_addr_in_fifo);
assert(f_eop_data[BW]);
if (f_first_in_fifo && f_first_data[BW])
assert(f_first_to_eop < (1<<LGFLEN));
if (f_second_in_fifo && f_second_data[BW])
assert(f_second_to_eop < (1<<LGFLEN));
end
// }}}
// Twin write state machine
// {{{
always @(posedge S_AXI_ACLK)
if (f_past_valid && $past(S_AXI_ARESETN))
begin
case({$past(f_first_in_fifo), $past(f_second_in_fifo)})
2'b00: begin
// {{{
if ($past(w_wr && (!w_rd || !r_empty))
&&($past(wr_addr == f_first_addr)))
begin
assert(f_first_in_fifo);
end else
assert(!f_first_in_fifo);
//
// The second could be in the FIFO, since
// one might write other data than f_first_data
//
// assert(!f_second_in_fifo);
end
// }}}
2'b01: begin
// {{{
assert(!f_first_in_fifo);
if ($past(w_rd && (rd_addr==f_second_addr)))
begin
assert((!M_AXIN_READY&&!OPT_ASYNC_READ)||!f_second_in_fifo);
end else
assert(f_second_in_fifo);
end
// }}}
2'b10: begin
// {{{
if ($past(w_wr)
&&($past(wr_addr == f_second_addr)))
begin
assert(f_second_in_fifo);
end else
assert(!f_second_in_fifo);
if ((!$past(S_AXIN_ABORT)) // || $past(lastv))
&& ($past(!w_rd ||(rd_addr != f_first_addr))))
assert(f_first_in_fifo);
end
// }}}
2'b11: begin
// {{{
if (!$past(S_AXIN_ABORT) && !M_AXIN_ABORT) // || $past(lastv))
begin
assert(f_second_in_fifo);
if ($past(!w_rd ||(rd_addr != f_first_addr)))
begin
assert(f_first_in_fifo);
if (rd_addr == f_first_addr)
assert({ M_AXIN_LAST, M_AXIN_DATA } == f_first_data);
end else begin
assert(!f_first_in_fifo);
assert({ M_AXIN_LAST, M_AXIN_DATA } == f_second_data);
end
end
end
// }}}
endcase
end
// }}}
// }}}
////////////////////////////////////////////////////////////////////////
//
// Cover properties
// {{{
////////////////////////////////////////////////////////////////////////
//
//
reg f_was_full;
initial f_was_full = 0;
always @(posedge S_AXI_ACLK)
if (!S_AXIN_READY)
f_was_full <= 1;
`ifdef SFIFO
always @(posedge S_AXI_ACLK)
cover($fell(f_empty));
always @(posedge S_AXI_ACLK)
cover($fell(!M_AXIN_READY));
always @(posedge S_AXI_ACLK)
cover(f_was_full && f_empty);
always @(posedge S_AXI_ACLK)
cover($past(!S_AXIN_READY,2)&&(!$past(!S_AXIN_READY))&&(!S_AXIN_READY));
always @(posedge S_AXI_ACLK)
if (f_past_valid)
cover($past(!M_AXIN_READY,2)&&(!$past(!M_AXIN_READY))&& !M_AXIN_READY);
`endif
// }}}
////////////////////////////////////////////////////////////////////////
//
// Simplifying assumptions
// {{{
////////////////////////////////////////////////////////////////////////
//
//
// always @(*)
// assume(!S_AXIN_ABORT);
// }}}
// Make Verilator happy
// {{{
// Verilator lint_off UNUSED
wire unused_formal;
assign unused_formal = &{ 1'b0, f_was_full, faxin_spkts, faxin_mpkts,
faxin_swords, faxin_mwords, f_empty, f_next };
// Verilator lint_on UNUSED
// }}}
`endif // FORMAL
// }}}
endmodule
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