gateware

crctool.c (3960B)

---

 // 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;
 }