crc.c

操作系统SunOS 4.1.3版本的源码

#ifndef lint
static char sccsid[] = "@(#)crc.c 1.1 92/07/30";
#endif

/*
 * crc - computes Cyclic Redundancy Checksum for a file.
 * This version only works for a disk partition under SunOS 4.x or greater.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sun/dklabel.h>
#include <sun/dkio.h>
#include <fcntl.h>
#include <string.h>
#include <varargs.h>

extern void exit();

typedef unsigned long tcrc;	/* type of crc value */
static int getpartsize();
static char *makebdev(), *makecdev();
static void err(), perr();

#ifdef USE_ASM
extern tcrc addbfcrc();
#else
/*
 * from brik distribution "::[[ @(#) addbfcrc.c 1.10 89/07/08 10:34:48 ]]::"
 * Adapted from zmodem source code, which contained Gary Brown's code
 *					-- Rahul Dhesi
 */

tcrc
addbfcrc(buf, size, crc)
	register char *buf;
	register int size;
	register tcrc crc;
{
	register int i;
	extern tcrc crctab[];

	for (i = 0;  i < size;  ++i)
		crc = crctab[(int)(crc ^ buf[i]) & 0xff] ^ (crc >> 8);
	return (crc);
}
#endif USE_ASM

main(argc, argv)
	int argc;
	char **argv;
{
	register int fd, size;
	register caddr_t pa;
	struct stat sbuf;
	char *fname;

	if (argc != 2)
		err(1, "Usage: %s file\n", argv[0]);

	if (stat(argv[1], &sbuf) == -1)
		perr(1, argv[1]);
	switch (sbuf.st_mode & S_IFMT) {
	case S_IFREG:
		fname = argv[1];
		size = (int)sbuf.st_size;
		break;
	case S_IFBLK:
		fname = argv[1];
		size = getpartsize(makecdev(fname));
		break;
	case S_IFCHR:
		fname = makebdev(argv[1]);
		size = getpartsize(argv[1]);
		break;
	default:
		err(1, "%s not a file, block or character device\n", argv[1]);
	}

	if ((fd = open(fname, O_RDONLY)) < 0)
		perr(1, fname);
	pa = mmap((caddr_t)0, roundup(size, getpagesize()), PROT_READ,
	    MAP_PRIVATE, fd, (off_t)0);
	if (pa == (caddr_t)-1)
		perr(1, "mmap");
	(void) printf("%u\n", addbfcrc((char *)pa, size, (tcrc)-1));
	(void) close(fd);
	exit(0);
	/* NOTREACHED */
}

static int
getpartsize(f)
	char *f;
{
	register int fd;
	struct dk_map p;

	if ((fd = open(f, O_RDONLY)) < 0)
		perr(1, f);
	if (ioctl(fd, DKIOCGPART, &p) == 0)
		return (p.dkl_nblk * DEV_BSIZE);
	perr(1, "can't get partition info");
	(void) close(fd);
	return (0);
}

static char *
makebdev(s)
	char *s;
{
	register char *new, *tail;

	if ((new = strdup(s)) == NULL)
		err(1, "couldn't duplicate string");
	if ((tail = strchr(new, 'r')) == NULL)
		err(1, "raw device name '%s' doesn't contain 'r'", new);
	while (*tail) {
		*tail = *(tail+1);
		++tail;
	}
	return (new);
}

static char *
makecdev(s)
	register char *s;
{
	register char *new, *tail, *cp;
	extern char *malloc();

	tail = strrchr(s, '/');
	if (tail == NULL)
		tail = s;
	else
		++tail;
	if ((new = malloc((unsigned)strlen(s) + 1)) == NULL)
		perr(1, "malloc");
	cp = new;
	while (s != tail)
		*cp++ = *s++;
	*cp++ = 'r';
	while (*s)
		*cp++ = *s++;
	return (new);

}

static void
perr(code, s)
	int code;
	char *s;
{
	perror(s);
	exit(code);
	/* NOTREACHED */
}

/* VARARGS */
static void
err(va_alist)
	va_dcl
{
	va_list pvar;
	int code;
	char *fmt;

	va_start(pvar);
	code = va_arg(pvar, int);
	fmt = va_arg(pvar, char *);
	(void) vprintf(fmt, pvar);
	(void) putchar('\n');
	va_end(pvar);
	exit(code);
	/* NOTREACHED */
}

/*
 * Remainder of this file is from "brik" distribution.
 */


/*
 * I claim no copyright over the contents of this file.  However,
 * you are requested to preserve all author attributions.
 *
 *					-- Rahul Dhesi
 */

/*
 * 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.
 */

tcrc crctab[] = { /* CRC polynomial 0xedb88320, see below */
	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
};

#ifdef NOT

/*
 * The function mkcrctab() generates a CRC-32 table at runtime.  The table
 * generated is identical to that shown above.
 *
 * Based on explanation and code in "C Programmer's Guide to Serial
 * Communications" by Joe Campbell.
 *
 * Rahul Dhesi, 28 March 1989.
 */

#define	CRC_32		0xedb88320L	/* CRC-32 polynomial */
#define	TABSIZE		256		/* no of entries in table */

/*
 * calculates CRC of one item
 */
tcrc onecrc (item)
int item;
{
	int i;
	tcrc accum = 0;
	item <<= 1;
	for (i = 8;  i > 0;  i--) {
		item >>= 1;
		if ((item ^ accum) & 0x0001)
			accum = (accum >> 1) ^ CRC_32;
		else
			accum >>= 1;
	}
	return (accum);
}

/*
 * generates CRC table, calling onecrc() to make each term
 */
void mkcrctab()
{
	int i;
	for (i = 0;  i < TABSIZE;  i++)
		crctab[i] = onecrc (i);
}

/*
 * test code -- prints entire table to standard output
 */
main()
{
	int i;

	mkcrctab();		/* make CRC table */
	/* now print it */
	for (i = 0;  i < TABSIZE;  i ++) {
		if ((i % 4) == 0 && i > 0)
			printf ("\n");
		printf("0x%08lx   ", (unsigned long) crctab[i]);
	}
	printf("\n");
}

#endif NOT