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rewrite bridge_rx and add basic formal

This commit is contained in:
Fischer Moseley 2023-07-14 06:30:05 -07:00
parent 9771d80fd1
commit 1a536080f1
5 changed files with 178 additions and 108 deletions
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8
Makefile
View File

@ -83,6 +83,14 @@ lut_mem_tb:
vvp sim.out
rm sim.out
# Formal Verification
formal:
sby test/formal_verification/uart_rx.sby
formal_clean:
rm -rf test/formal_verification/*_basic
rm -rf test/formal_verification/*_cover
# Build Examples
examples: icestick nexys_a7

208
src/manta/uart_iface/bridge_rx.v
View File

@ -1,6 +1,25 @@
`default_nettype none
`timescale 1ns/1ps
function [3:0] from_ascii_hex;
// convert an ascii char encoding a hex value to
// the corresponding hex value
input [7:0] c;
if ((c >= 8'h30) && (c <= 8'h39)) from_ascii_hex = c - 8'h30;
else if ((c >= 8'h41) && (c <= 8'h46)) from_ascii_hex = c - 8'h41 + 'd1;
else from_ascii_hex = 0;
endfunction
function is_ascii_hex;
// checks if a byte is an ascii char encoding a hex digit
input [7:0] c;
if ((c >= 8'h30) && (c <= 8'h39)) is_ascii_hex = 1; // 0-9
else if ((c >= 8'h41) && (c <= 8'h46)) is_ascii_hex = 1; // A-F
else is_ascii_hex = 0;
endfunction
module bridge_rx (
input wire clk,
@ -8,123 +27,108 @@ module bridge_rx (
input wire valid_i,
output reg [15:0] addr_o,
output reg [15:0] wdata_o,
output reg [15:0] data_o,
output reg rw_o,
output reg valid_o);
// this is a hack, the FSM needs to be updated
// but this will bypass it for now
parameter ready_i = 1;
initial addr_o = 0;
initial data_o = 0;
initial rw_o = 0;
initial valid_o = 0;
parameter ADDR_WIDTH = 0;
parameter DATA_WIDTH = 0;
localparam PREAMBLE = 8'h4D;
localparam CR = 8'h0D;
localparam LF = 8'h0A;
localparam ACQUIRE = 0;
localparam TRANSMIT = 1;
localparam ERROR = 2;
reg [1:0] state;
reg [3:0] bytes_received;
// no global resets!
initial begin
addr_o = 0;
wdata_o = 0;
rw_o = 0;
valid_o = 0;
bytes_received = 0;
state = ACQUIRE;
end
reg [3:0] data_i_decoded;
reg data_i_is_0_thru_9;
reg data_i_is_A_thru_F;
always @(*) begin
data_i_is_0_thru_9 = (data_i >= 8'h30) & (data_i <= 8'h39);
data_i_is_A_thru_F = (data_i >= 8'h41) & (data_i <= 8'h46);
if (data_i_is_0_thru_9) data_i_decoded = data_i - 8'h30;
else if (data_i_is_A_thru_F) data_i_decoded = data_i - 8'h41 + 'd10;
else data_i_decoded = 0;
end
reg [7:0] buffer [7:0]; // todo: see if sby will tolerate packed arrays?
localparam IDLE = 0;
localparam READ = 1;
localparam WRITE = 2;
reg [1:0] state = 0;
reg [3:0] byte_num = 0;
always @(posedge clk) begin
if (state == ACQUIRE) begin
if(valid_i) begin
addr_o <= 0;
data_o <= 0;
rw_o <= 0;
valid_o <= 0;
if (bytes_received == 0) begin
if(data_i == PREAMBLE) bytes_received <= 1;
end
else if( (bytes_received >= 1) & (bytes_received <= 4) ) begin
// only advance if byte is valid hex digit
if(data_i_is_0_thru_9 | data_i_is_A_thru_F) begin
addr_o <= (addr_o << 4) | data_i_decoded;
bytes_received <= bytes_received + 1;
end
else state <= ERROR;
end
else if( bytes_received == 5) begin
if( (data_i == CR) | (data_i == LF)) begin
valid_o <= 1;
rw_o <= 0;
bytes_received <= 0;
state <= TRANSMIT;
end
else if (data_i_is_0_thru_9 | data_i_is_A_thru_F) begin
bytes_received <= bytes_received + 1;
wdata_o <= (wdata_o << 4) | data_i_decoded;
end
else state <= ERROR;
end
else if ( (bytes_received >= 6) & (bytes_received <= 8) ) begin
if (data_i_is_0_thru_9 | data_i_is_A_thru_F) begin
wdata_o <= (wdata_o << 4) | data_i_decoded;
bytes_received <= bytes_received + 1;
end
else state <= ERROR;
end
else if (bytes_received == 9) begin
bytes_received <= 0;
if( (data_i == CR) | (data_i == LF)) begin
valid_o <= 1;
rw_o <= 1;
state <= TRANSMIT;
end
else state <= ERROR;
end
end
if (state == IDLE) begin
byte_num <= 0;
if (valid_i) begin
if (data_i == "R") state <= READ;
if (data_i == "W") state <= WRITE;
end
end
else begin
if (valid_i) begin
// buffer bytes regardless of if they're good
byte_num <= byte_num + 1;
buffer[byte_num] <= data_i;
else if (state == TRANSMIT) begin
if(ready_i) begin
valid_o <= 0;
state <= ACQUIRE;
end
// current transaction specifies a read operation
if(state == READ) begin
if(valid_i) begin
if ( (data_i != CR) & (data_i != LF)) begin
valid_o <= 0;
state <= ERROR;
// go to idle if anything doesn't make sense
if(byte_num <= 3)
if(!is_ascii_hex(data_i)) state <= IDLE;
else if(byte_num == 4)
if(data_i != CR) state <= IDLE;
else if(byte_num == 5) begin
state <= IDLE;
// put data on the bus if the last byte looks good
if(data_i == LF) begin
addr_o <= (from_ascii_hex(buffer[0]) << 12) |
(from_ascii_hex(buffer[1]) << 8) |
(from_ascii_hex(buffer[2]) << 4) |
(from_ascii_hex(buffer[3]));
data_o <= 0;
rw_o <= 0;
valid_o <= 1;
end
end
end
// current transaction specifies a write transaction
if(state == WRITE) begin
// go to idle if anything doesn't make sense
if(byte_num <= 3)
if(!is_ascii_hex(data_i)) state <= IDLE;
else if(byte_num == 4)
if(data_i != CR) state <= IDLE;
else if(byte_num == 5) begin
state <= IDLE;
// put data on the bus if the last byte looks good
if(data_i == LF) begin
addr_o <= (from_ascii_hex(buffer[0]) << 12) |
(from_ascii_hex(buffer[1]) << 8) |
(from_ascii_hex(buffer[2]) << 4) |
(from_ascii_hex(buffer[3]));
data_o <= (from_ascii_hex(buffer[4]) << 12) |
(from_ascii_hex(buffer[5]) << 8) |
(from_ascii_hex(buffer[6]) << 4) |
(from_ascii_hex(buffer[7]));
rw_o <= 1;
valid_o <= 1;
end
end
end
end
end
end
`ifdef FORMAL
always @(posedge clk) begin
cover(data_o == 16'h1234);
//cover(data_o == 16'h1234 && addr_o == 16'h5678 && rw_o == 1 && valid_o == 1);
end
`endif // FORMAL
endmodule
`default_nettype wire

12
src/manta/uart_iface/bridge_tx.v
View File

@ -1,10 +1,10 @@
`default_nettype none
`timescale 1ns/1ps
function [7:0] ascii_hex;
function [7:0] to_ascii_hex;
// convert a number from 0-15 into the corresponding ascii char
input [3:0] n;
ascii_hex = (n > 10) ? (n + 8'h30) : (n + 8'h41 - 'd10);
to_ascii_hex = (n > 10) ? (n + 8'h30) : (n + 8'h41 - 'd10);
endfunction
module bridge_tx (
@ -57,10 +57,10 @@ module bridge_tx (
always @(*) begin
case (count)
0: data_o = PREAMBLE;
1: data_o = ascii_hex(buffer[15:12]);
2: data_o = ascii_hex(buffer[11:8]);
3: data_o = ascii_hex(buffer[7:4]);
4: data_o = ascii_hex(buffer[3:0]);
1: data_o = to_ascii_hex(buffer[15:12]);
2: data_o = to_ascii_hex(buffer[11:8]);
3: data_o = to_ascii_hex(buffer[7:4]);
4: data_o = to_ascii_hex(buffer[3:0]);
5: data_o = CR;
6: data_o = LF;
default: data_o = 0;

29
test/formal_verification/bridge_rx.sby Normal file
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@ -0,0 +1,29 @@
[tasks]
basic bmc
nofullskip prove
cover
noverific cover
basic cover : default
[options]
cover:
mode cover
--
prove:
mode prove
--
bmc:
mode bmc
--
[engines]
smtbmc boolector
[script]
nofullskip: read -define NO_FULL_SKIP=1
noverific: read -noverific
read -formal bridge_rx.v
prep -top bridge_rx
[files]
src/manta/uart_iface/bridge_rx.v

29
test/formal_verification/uart_rx.sby Normal file
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@ -0,0 +1,29 @@
[tasks]
basic bmc
nofullskip prove
cover
noverific cover
basic cover : default
[options]
cover:
mode cover
--
prove:
mode prove
--
bmc:
mode bmc
--
[engines]
smtbmc boolector
[script]
nofullskip: read -define NO_FULL_SKIP=1
noverific: read -noverific
read -formal uart_rx.v
prep -top uart_rx
[files]
src/manta/uart_iface/uart_rx.v