CRC module.

ccan/crc/_info.c

+#include <string.h>
+
+/**
+ * crc - routines for crc of bytes
+ *
+ * Cyclic Redundancy Check routines.  They are reasonably fasts
+ * checksum routine, but not suitable for cryptographic use.
+ *
+ * They are useful for simple error detection, eg. a 32-bit CRC will
+ * detect a single error burst of up to 32 bits.
+ *
+ * Example:
+ *	#include <ccan/crc.h>
+ *	#include <stdio.h>
+ *	#include <stdlib.h>
+ *
+ *	int main(int argc, char *argv[])
+ *	{
+ *		if (argc != 2) {
+ *			fprintf(stderr, "Usage: %s <string>\n"
+ *				"Prints 32 bit CRC of the string\n", argv[0]);
+ *			exit(1);
+ *		}
+ *		printf("0x%08x\n", crc32(argv[1], strlen(argv[1])));
+ *		exit(0);
+ *	}
+ *
+ * Licence: Public Domain
+ * Author: Gary S. Brown
+ * Maintainer: Rusty Russell <rusty@rustcorp.com.au>
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}

ccan/crc/crc.c

+/*-
+ *  COPYRIGHT (C) 1986 Gary S. Brown.  You may use this program, or
+ *  code or tables extracted from it, as desired without restriction.
+ *
+ *  First, the polynomial itself and its table of feedback terms.  The
+ *  polynomial is
+ *  X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0
+ *
+ *  Note that we take it "backwards" and put the highest-order term in
+ *  the lowest-order bit.  The X^32 term is "implied"; the LSB is the
+ *  X^31 term, etc.  The X^0 term (usually shown as "+1") results in
+ *  the MSB being 1
+ *
+ *  Note that the usual hardware shift register implementation, which
+ *  is what we're using (we're merely optimizing it by doing eight-bit
+ *  chunks at a time) shifts bits into the lowest-order term.  In our
+ *  implementation, that means shifting towards the right.  Why do we
+ *  do it this way?  Because the calculated CRC must be transmitted in
+ *  order from highest-order term to lowest-order term.  UARTs transmit
+ *  characters in order from LSB to MSB.  By storing the CRC this way
+ *  we hand it to the UART in the order low-byte to high-byte; the UART
+ *  sends each low-bit to hight-bit; and the result is transmission bit
+ *  by bit from highest- to lowest-order term without requiring any bit
+ *  shuffling on our part.  Reception works similarly
+ *
+ *  The feedback terms table consists of 256, 32-bit entries.  Notes
+ *
+ *      The table can be generated at runtime if desired; code to do so
+ *      is shown later.  It might not be obvious, but the feedback
+ *      terms simply represent the results of eight shift/xor opera
+ *      tions for all combinations of data and CRC register values
+ *
+ *      The values must be right-shifted by eight bits by the "updcrc
+ *      logic; the shift must be unsigned (bring in zeroes).  On some
+ *      hardware you could probably optimize the shift in assembler by
+ *      using byte-swap instructions
+ *      polynomial $edb88320
+ *
+ *
+ * CRC32 code derived from work by Gary S. Brown.
+ */
+#include "crc.h"
+#include <stdbool.h>
+#include <stdlib.h>
+
+static const uint32_t crc32_tab[] = {
+	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+	0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+	0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+	0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+	0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+	0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
+	0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+	0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+	0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+	0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
+	0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+	0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+	0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+	0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+	0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+	0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+	0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+	0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+	0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+	0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+	0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+	0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+	0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+	0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+	0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+	0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+	0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+	0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+	0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+	0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+	0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+	0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+	0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+	0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+	0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+	0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+	0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+	0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+	0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+	0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+	0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+	0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+uint32_t crc32(const void *buf, size_t size)
+{
+	const uint8_t *p;
+	uint32_t crc;
+
+	p = buf;
+	crc = ~0U;
+
+	while (size--)
+		crc = crc32_tab[(crc ^ *p++) & 0xFF] ^ (crc >> 8);
+
+	return crc ^ ~0U;
+}

ccan/crc/crc.h

+#ifndef CCAN_CRC_H
+#define CCAN_CRC_H
+#include <stdint.h>
+#include <stdlib.h>
+
+/**
+ * crc32 - 32 bit crc of string of bytes
+ * @buf: pointer to bytes
+ * @size: length of buffer
+ *
+ * 32 bit CRC checksum using polynomial
+ * X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0.
+ */
+uint32_t crc32(const void *buf, size_t size);
+#endif /* CCAN_CRC_H */

ccan/crc/test/api.c

+#include "crc/crc.h"
+#include "crc/crc.c"
+#include "tap/tap.h"
+#include <string.h>
+
+/* Expected CRCs of 4 of each char. */
+static uint32_t crc_expect[] = {
+	0x2144df1c, 0xf626d399, 0x54f1c057, 0x8393ccd2, 0xca2ee18a, 0x1d4ced0f,
+	0xbf9bfec1, 0x68f9f244, 0x2ce1a471, 0xfb83a8f4, 0x5954bb3a, 0x8e36b7bf,
+	0xc78b9ae7, 0x10e99662, 0xb23e85ac, 0x655c8929, 0x3a0e29c6, 0xed6c2543,
+	0x4fbb368d, 0x98d93a08, 0xd1641750, 0x06061bd5, 0xa4d1081b, 0x73b3049e,
+	0x37ab52ab, 0xe0c95e2e, 0x421e4de0, 0x957c4165, 0xdcc16c3d, 0x0ba360b8,
+	0xa9747376, 0x7e167ff3, 0x17d132a8, 0xc0b33e2d, 0x62642de3, 0xb5062166,
+	0xfcbb0c3e, 0x2bd900bb, 0x890e1375, 0x5e6c1ff0, 0x1a7449c5, 0xcd164540,
+	0x6fc1568e, 0xb8a35a0b, 0xf11e7753, 0x267c7bd6, 0x84ab6818, 0x53c9649d,
+	0x0c9bc472, 0xdbf9c8f7, 0x792edb39, 0xae4cd7bc, 0xe7f1fae4, 0x3093f661,
+	0x9244e5af, 0x4526e92a, 0x013ebf1f, 0xd65cb39a, 0x748ba054, 0xa3e9acd1,
+	0xea548189, 0x3d368d0c, 0x9fe19ec2, 0x48839247, 0x4c6f0474, 0x9b0d08f1,
+	0x39da1b3f, 0xeeb817ba, 0xa7053ae2, 0x70673667, 0xd2b025a9, 0x05d2292c,
+	0x41ca7f19, 0x96a8739c, 0x347f6052, 0xe31d6cd7, 0xaaa0418f, 0x7dc24d0a,
+	0xdf155ec4, 0x08775241, 0x5725f2ae, 0x8047fe2b, 0x2290ede5, 0xf5f2e160,
+	0xbc4fcc38, 0x6b2dc0bd, 0xc9fad373, 0x1e98dff6, 0x5a8089c3, 0x8de28546,
+	0x2f359688, 0xf8579a0d, 0xb1eab755, 0x6688bbd0, 0xc45fa81e, 0x133da49b,
+	0x7afae9c0, 0xad98e545, 0x0f4ff68b, 0xd82dfa0e, 0x9190d756, 0x46f2dbd3,
+	0xe425c81d, 0x3347c498, 0x775f92ad, 0xa03d9e28, 0x02ea8de6, 0xd5888163,
+	0x9c35ac3b, 0x4b57a0be, 0xe980b370, 0x3ee2bff5, 0x61b01f1a, 0xb6d2139f,
+	0x14050051, 0xc3670cd4, 0x8ada218c, 0x5db82d09, 0xff6f3ec7, 0x280d3242,
+	0x6c156477, 0xbb7768f2, 0x19a07b3c, 0xcec277b9, 0x877f5ae1, 0x501d5664,
+	0xf2ca45aa, 0x25a8492f, 0xfb1369cc, 0x2c716549, 0x8ea67687, 0x59c47a02,
+	0x1079575a, 0xc71b5bdf, 0x65cc4811, 0xb2ae4494, 0xf6b612a1, 0x21d41e24,
+	0x83030dea, 0x5461016f, 0x1ddc2c37, 0xcabe20b2, 0x6869337c, 0xbf0b3ff9,
+	0xe0599f16, 0x373b9393, 0x95ec805d, 0x428e8cd8, 0x0b33a180, 0xdc51ad05,
+	0x7e86becb, 0xa9e4b24e, 0xedfce47b, 0x3a9ee8fe, 0x9849fb30, 0x4f2bf7b5,
+	0x0696daed, 0xd1f4d668, 0x7323c5a6, 0xa441c923, 0xcd868478, 0x1ae488fd,
+	0xb8339b33, 0x6f5197b6, 0x26ecbaee, 0xf18eb66b, 0x5359a5a5, 0x843ba920,
+	0xc023ff15, 0x1741f390, 0xb596e05e, 0x62f4ecdb, 0x2b49c183, 0xfc2bcd06,
+	0x5efcdec8, 0x899ed24d, 0xd6cc72a2, 0x01ae7e27, 0xa3796de9, 0x741b616c,
+	0x3da64c34, 0xeac440b1, 0x4813537f, 0x9f715ffa, 0xdb6909cf, 0x0c0b054a,
+	0xaedc1684, 0x79be1a01, 0x30033759, 0xe7613bdc, 0x45b62812, 0x92d42497,
+	0x9638b2a4, 0x415abe21, 0xe38dadef, 0x34efa16a, 0x7d528c32, 0xaa3080b7,
+	0x08e79379, 0xdf859ffc, 0x9b9dc9c9, 0x4cffc54c, 0xee28d682, 0x394ada07,
+	0x70f7f75f, 0xa795fbda, 0x0542e814, 0xd220e491, 0x8d72447e, 0x5a1048fb,
+	0xf8c75b35, 0x2fa557b0, 0x66187ae8, 0xb17a766d, 0x13ad65a3, 0xc4cf6926,
+	0x80d73f13, 0x57b53396, 0xf5622058, 0x22002cdd, 0x6bbd0185, 0xbcdf0d00,
+	0x1e081ece, 0xc96a124b, 0xa0ad5f10, 0x77cf5395, 0xd518405b, 0x027a4cde,
+	0x4bc76186, 0x9ca56d03, 0x3e727ecd, 0xe9107248, 0xad08247d, 0x7a6a28f8,
+	0xd8bd3b36, 0x0fdf37b3, 0x46621aeb, 0x9100166e, 0x33d705a0, 0xe4b50925,
+	0xbbe7a9ca, 0x6c85a54f, 0xce52b681, 0x1930ba04, 0x508d975c, 0x87ef9bd9,
+	0x25388817, 0xf25a8492, 0xb642d2a7, 0x6120de22, 0xc3f7cdec, 0x1495c169,
+	0x5d28ec31, 0x8a4ae0b4, 0x289df37a, 0xffffffff,
+};
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	char c[4] = { 0 };
+
+	plan_tests(260);
+	ok1(crc32(c, 0) == 0x00000000);
+	ok1(crc32(c, 1) == 0xd202ef8d);
+	ok1(crc32(c, 2) == 0x41d912ff);
+	ok1(crc32(c, 3) == 0xff41d912);
+
+	for (i = 0; i < 256; i++) {
+		memset(c, i, sizeof(c));
+		ok1(crc32(c, sizeof(c)) == crc_expect[i]);
+	}
+	return exit_status();
+}