gateware

commit ed30ef3614097f55ff3018f7d1a480c02c625528
parent 46e23bbc9a404b70cea02c6bc093408ac5e00c43
Author: Brian Swetland <swetland@frotz.net>
Date:   Mon, 17 Dec 2018 16:04:43 -0800

crctool: generate verilog for crc blocks

Diffstat:
M
Makefile
 | 
6
+++++-
A
src/crctool.c
 | 
150
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 155 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
@@ -46,7 +46,11 @@ out/icetool: src/icetool.c src/ftdi.c src/ftdi.h
 	@mkdir -p out
 	gcc -g -Wall -O1 -o out/icetool src/icetool.c src/ftdi.c -lusb-1.0 -lrt
 
-tools:: out/a16 out/d16 out/icetool out/udebug
+out/crctool: src/crctool
+	@mkdir -p out
+	gcc -g -Wall -O1 -o out/crctool src/crctool.c
+
+tools:: out/a16 out/d16 out/icetool out/udebug out/crctool
 
 build-all-buildable:: $(ALL_BUILDS) tools
 
diff --git a/src/crctool.c b/src/crctool.c
@@ -0,0 +1,150 @@
+// Copyright 2015, Brian Swetland <swetland@frotz.net>
+// Licensed under the Apache License, Version 2.0.
+
+// Based on "A Practical Parallel CRC Generation Method" by Evgeni Stavinov,
+// published in Circuit Cellar, January 2010
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+uint32_t serial_crc(uint32_t crc, uint32_t poly, size_t nbits, uint32_t din) {
+	din = din ^ ((crc >> (nbits-1)) & 1);
+	crc <<= 1;
+	if (din) crc ^= poly;
+	return crc & (0xFFFFFFFF >> (32-nbits));
+}
+
+uint32_t parallel_crc(uint32_t crc, uint32_t poly, size_t nbits, uint32_t din, size_t dbits, int LSB) {
+	for (size_t n = 0; n < dbits; n++) {
+		if (LSB) {
+			crc = serial_crc(crc, poly, nbits, din & 1);
+			din >>= 1;
+		} else {
+			crc = serial_crc(crc, poly, nbits, (din >> (dbits-1)) & 1);
+			din <<= 1;
+		}
+	}
+	return crc;
+}
+
+char* binary(uint32_t n, size_t bits) {
+	static char out[33];
+	char *p = out;
+	while (bits-- > 0) {
+		*p++ = '0' + ((n >> bits) & 1);
+	}
+	*p = 0;
+	return out;
+}
+
+int main(int argc, char** argv) {
+	size_t crcsz = 5;
+	uint32_t poly = 5;
+	size_t dinsz = 4;
+	int reverse = 0;
+	int invert = 0;
+	int lsb = 0;
+
+	while (argc > 1) {
+		if (!strcmp(argv[1], "-help")) {
+			fprintf(stderr, "usage: crctool -poly=<hex> -crcsz=<bits> -dinsz=<bits> [-reverse] [-invert]\n");
+			return 0;
+		} else if (!strcmp(argv[1], "-reverse")) {
+			reverse = 1;
+		} else if (!strcmp(argv[1], "-invert")) {
+			invert = 1;
+		} else if (!strncmp(argv[1], "-poly=", 6)) {
+			poly = strtoul(argv[1] + 6, NULL, 16);
+		} else if(!strncmp(argv[1], "-crcsz=", 7)) {
+			crcsz = strtoul(argv[1] + 7, NULL, 10);
+		} else if(!strncmp(argv[1], "-dinsz=", 7)) {
+			dinsz = strtoul(argv[1] + 7, NULL, 10);
+		} else {
+			fprintf(stderr, "error: unknown option: %s\n", argv[1]);
+			return -1;
+		}
+		argv++;
+		argc--;
+	}
+	if ((crcsz < 2) || (crcsz > 32)) {
+		fprintf(stderr, "error: crc size %zu unsupported\n", crcsz);
+		return -1;
+	}
+	if ((dinsz < 1) || (dinsz > crcsz)) {
+		fprintf(stderr, "error: din size %zu unsupported\n", dinsz);
+		return -1;
+	}
+
+	uint32_t h1[32];
+	for (size_t n = 0; n < dinsz; n++) {
+		h1[n] = parallel_crc(0, poly, crcsz, 1 << n, dinsz, lsb);
+		//fprintf(stderr, "h1[%zu] = %s\n", n, binary(h1[n], crcsz));
+	}
+
+	uint32_t h2[32];
+	for (size_t n = 0; n < crcsz; n++) {
+		h2[n] = parallel_crc(1 << n, poly, crcsz, 0, dinsz, lsb);
+		//fprintf(stderr, "h2[%zu] = %s\n", n, binary(h2[n], crcsz));
+	}
+
+	printf("// autogenerated by crctool -poly=%x -crcsz=%zu -dinsz=%zu%s%s\n\n",
+		poly, crcsz, dinsz, reverse ? " -reverse" : "", invert ? " -invert" : "");
+	printf("module crc_%zu_%x_%zu(\n", crcsz, poly, dinsz);
+	printf("\tinput clk,\n");
+	printf("\tinput rst,\n");
+	printf("\tinput en,\n");
+	printf("\tinput [%zu:0]din,\n", dinsz - 1);
+	printf("\toutput [%zu:0]crc\n", crcsz - 1);
+	printf("\t);\n" "\n" "reg [%zu:0]c;\n" "reg [%zu:0]n;\n" "\n", crcsz - 1, crcsz - 1);
+	if (reverse) {
+		printf("wire [%zu:0]d = {din[0]", dinsz - 1);
+		for (size_t n = 1; n < dinsz; n++) {
+			printf(",din[%zu]", n);
+		}
+		printf("};\n\n");
+		printf("assign crc = %s{\n\tc[0]", invert ? "~" : "");
+		for (size_t n = 1; n < crcsz; n++) {
+			if ((n % 8) == 0) printf("\n\t");
+			printf(",c[%zu]", n);
+		}
+		printf("\n\t};\n\n");
+	} else {
+		printf("wire [%zu:0]d = din;\n\n", dinsz - 1);
+		printf("assign crc = %sc;\n\n", invert ? "~" : "");
+	}
+	printf("always_comb begin\n");
+	for (size_t n = 0; n < crcsz; n++) {
+		char* op = " = ";
+		printf("\tn[%zu]", n);
+		uint32_t bit = 1 << n;
+		for (size_t i = 0; i < crcsz; i++) {
+			if (h2[i] & bit) {
+				printf("%sc[%zu]", op, i);
+				op = "^";
+			}
+		}
+		for (size_t i = 0; i < dinsz; i++) {
+			if (h1[i] & bit) {
+				printf("%sd[%zu]", op, i);
+				op = "^";
+			}
+		}
+		printf(";\n");
+	}
+
+	printf(
+"end\n"
+"\n"
+"always_ff @(posedge clk) begin\n"
+"\tif (rst) begin\n"
+"\t\tc <= %zu'h%X;\n"
+"\tend else if (en) begin\n"
+"\t\tc <= n;\n"
+"\tend\n"
+"end\n"
+"\n"
+"endmodule\n", crcsz, 0xFFFFFFFF >> (32 - crcsz));
+	return 0;
+}