[openssh.git] / crc32.c

/*
 * The implementation here was originally done by Gary S. Brown.
 * I have borrowed the tables directly, and made some minor changes
 * to the crc32-function (including changing the interface).
 * //ylo
 */

#include "includes.h"
RCSID("$OpenBSD: crc32.c,v 1.6 2000/08/19 02:17:12 deraadt Exp $");

#include "crc32.h"

  /* ============================================================= */
  /*  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                                              */
  /*                                                                        */
  /*  --------------------------------------------------------------------  */

static unsigned int crc32_tab[] = {
	0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
	0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
	0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
	0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
	0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
	0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
	0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
	0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
	0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
	0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
	0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
	0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
	0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
	0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
	0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
	0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
	0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
	0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
	0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
	0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
	0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
	0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
	0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
	0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
	0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
	0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
	0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
	0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
	0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
	0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
	0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
	0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
	0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
	0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
	0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
	0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
	0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
	0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
	0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
	0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
	0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
	0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
	0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
	0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
	0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
	0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
	0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
	0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
	0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
	0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
	0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
	0x2d02ef8dL
};

/* Return a 32-bit CRC of the contents of the buffer. */

unsigned int
ssh_crc32(const unsigned char *s, unsigned int len)
{
	unsigned int i;
	unsigned int crc32val;

	crc32val = 0;
	for (i = 0;  i < len;  i ++) {
		crc32val = crc32_tab[(crc32val ^ s[i]) & 0xff] ^ (crc32val >> 8);
	}
	return crc32val;
}
Commit	Line	Data
5260325f	1	/*
	2	* The implementation here was originally done by Gary S. Brown.
	3	* I have borrowed the tables directly, and made some minor changes
	4	* to the crc32-function (including changing the interface).
	5	* //ylo
	6	*/
8efc0c15	7
8efc0c15	8	#include "includes.h"
2e73a022	9	RCSID("$OpenBSD: crc32.c,v 1.6 2000/08/19 02:17:12 deraadt Exp $");
8efc0c15	10
	11	#include "crc32.h"
	12
	13	/* ============================================================= */
	14	/* COPYRIGHT (C) 1986 Gary S. Brown. You may use this program, or */
	15	/* code or tables extracted from it, as desired without restriction. */
	16	/* */
	17	/* First, the polynomial itself and its table of feedback terms. The */
	18	/* polynomial is */
	19	/* 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 */
	20	/* */
	21	/* Note that we take it "backwards" and put the highest-order term in */
	22	/* the lowest-order bit. The X^32 term is "implied"; the LSB is the */
	23	/* X^31 term, etc. The X^0 term (usually shown as "+1") results in */
	24	/* the MSB being 1. */
	25	/* */
	26	/* Note that the usual hardware shift register implementation, which */
	27	/* is what we're using (we're merely optimizing it by doing eight-bit */
	28	/* chunks at a time) shifts bits into the lowest-order term. In our */
	29	/* implementation, that means shifting towards the right. Why do we */
	30	/* do it this way? Because the calculated CRC must be transmitted in */
	31	/* order from highest-order term to lowest-order term. UARTs transmit */
	32	/* characters in order from LSB to MSB. By storing the CRC this way, */
	33	/* we hand it to the UART in the order low-byte to high-byte; the UART */
	34	/* sends each low-bit to hight-bit; and the result is transmission bit */
	35	/* by bit from highest- to lowest-order term without requiring any bit */
	36	/* shuffling on our part. Reception works similarly. */
	37	/* */
	38	/* The feedback terms table consists of 256, 32-bit entries. Notes: */
	39	/* */
	40	/* The table can be generated at runtime if desired; code to do so */
	41	/* is shown later. It might not be obvious, but the feedback */
	42	/* terms simply represent the results of eight shift/xor opera- */
	43	/* tions for all combinations of data and CRC register values. */
	44	/* */
	45	/* The values must be right-shifted by eight bits by the "updcrc" */
	46	/* logic; the shift must be unsigned (bring in zeroes). On some */
	47	/* hardware you could probably optimize the shift in assembler by */
	48	/* using byte-swap instructions. */
	49	/* polynomial $edb88320 */
	50	/* */
	51	/* -------------------------------------------------------------------- */
	52
	53	static unsigned int crc32_tab[] = {
5260325f	54	0x00000000L, 0x77073096L, 0xee0e612cL, 0x990951baL, 0x076dc419L,
	55	0x706af48fL, 0xe963a535L, 0x9e6495a3L, 0x0edb8832L, 0x79dcb8a4L,
	56	0xe0d5e91eL, 0x97d2d988L, 0x09b64c2bL, 0x7eb17cbdL, 0xe7b82d07L,
	57	0x90bf1d91L, 0x1db71064L, 0x6ab020f2L, 0xf3b97148L, 0x84be41deL,
	58	0x1adad47dL, 0x6ddde4ebL, 0xf4d4b551L, 0x83d385c7L, 0x136c9856L,
	59	0x646ba8c0L, 0xfd62f97aL, 0x8a65c9ecL, 0x14015c4fL, 0x63066cd9L,
	60	0xfa0f3d63L, 0x8d080df5L, 0x3b6e20c8L, 0x4c69105eL, 0xd56041e4L,
	61	0xa2677172L, 0x3c03e4d1L, 0x4b04d447L, 0xd20d85fdL, 0xa50ab56bL,
	62	0x35b5a8faL, 0x42b2986cL, 0xdbbbc9d6L, 0xacbcf940L, 0x32d86ce3L,
	63	0x45df5c75L, 0xdcd60dcfL, 0xabd13d59L, 0x26d930acL, 0x51de003aL,
	64	0xc8d75180L, 0xbfd06116L, 0x21b4f4b5L, 0x56b3c423L, 0xcfba9599L,
	65	0xb8bda50fL, 0x2802b89eL, 0x5f058808L, 0xc60cd9b2L, 0xb10be924L,
	66	0x2f6f7c87L, 0x58684c11L, 0xc1611dabL, 0xb6662d3dL, 0x76dc4190L,
	67	0x01db7106L, 0x98d220bcL, 0xefd5102aL, 0x71b18589L, 0x06b6b51fL,
	68	0x9fbfe4a5L, 0xe8b8d433L, 0x7807c9a2L, 0x0f00f934L, 0x9609a88eL,
	69	0xe10e9818L, 0x7f6a0dbbL, 0x086d3d2dL, 0x91646c97L, 0xe6635c01L,
	70	0x6b6b51f4L, 0x1c6c6162L, 0x856530d8L, 0xf262004eL, 0x6c0695edL,
	71	0x1b01a57bL, 0x8208f4c1L, 0xf50fc457L, 0x65b0d9c6L, 0x12b7e950L,
	72	0x8bbeb8eaL, 0xfcb9887cL, 0x62dd1ddfL, 0x15da2d49L, 0x8cd37cf3L,
	73	0xfbd44c65L, 0x4db26158L, 0x3ab551ceL, 0xa3bc0074L, 0xd4bb30e2L,
	74	0x4adfa541L, 0x3dd895d7L, 0xa4d1c46dL, 0xd3d6f4fbL, 0x4369e96aL,
	75	0x346ed9fcL, 0xad678846L, 0xda60b8d0L, 0x44042d73L, 0x33031de5L,
	76	0xaa0a4c5fL, 0xdd0d7cc9L, 0x5005713cL, 0x270241aaL, 0xbe0b1010L,
	77	0xc90c2086L, 0x5768b525L, 0x206f85b3L, 0xb966d409L, 0xce61e49fL,
	78	0x5edef90eL, 0x29d9c998L, 0xb0d09822L, 0xc7d7a8b4L, 0x59b33d17L,
	79	0x2eb40d81L, 0xb7bd5c3bL, 0xc0ba6cadL, 0xedb88320L, 0x9abfb3b6L,
	80	0x03b6e20cL, 0x74b1d29aL, 0xead54739L, 0x9dd277afL, 0x04db2615L,
	81	0x73dc1683L, 0xe3630b12L, 0x94643b84L, 0x0d6d6a3eL, 0x7a6a5aa8L,
	82	0xe40ecf0bL, 0x9309ff9dL, 0x0a00ae27L, 0x7d079eb1L, 0xf00f9344L,
	83	0x8708a3d2L, 0x1e01f268L, 0x6906c2feL, 0xf762575dL, 0x806567cbL,
	84	0x196c3671L, 0x6e6b06e7L, 0xfed41b76L, 0x89d32be0L, 0x10da7a5aL,
	85	0x67dd4accL, 0xf9b9df6fL, 0x8ebeeff9L, 0x17b7be43L, 0x60b08ed5L,
	86	0xd6d6a3e8L, 0xa1d1937eL, 0x38d8c2c4L, 0x4fdff252L, 0xd1bb67f1L,
	87	0xa6bc5767L, 0x3fb506ddL, 0x48b2364bL, 0xd80d2bdaL, 0xaf0a1b4cL,
	88	0x36034af6L, 0x41047a60L, 0xdf60efc3L, 0xa867df55L, 0x316e8eefL,
	89	0x4669be79L, 0xcb61b38cL, 0xbc66831aL, 0x256fd2a0L, 0x5268e236L,
	90	0xcc0c7795L, 0xbb0b4703L, 0x220216b9L, 0x5505262fL, 0xc5ba3bbeL,
	91	0xb2bd0b28L, 0x2bb45a92L, 0x5cb36a04L, 0xc2d7ffa7L, 0xb5d0cf31L,
	92	0x2cd99e8bL, 0x5bdeae1dL, 0x9b64c2b0L, 0xec63f226L, 0x756aa39cL,
	93	0x026d930aL, 0x9c0906a9L, 0xeb0e363fL, 0x72076785L, 0x05005713L,
	94	0x95bf4a82L, 0xe2b87a14L, 0x7bb12baeL, 0x0cb61b38L, 0x92d28e9bL,
	95	0xe5d5be0dL, 0x7cdcefb7L, 0x0bdbdf21L, 0x86d3d2d4L, 0xf1d4e242L,
	96	0x68ddb3f8L, 0x1fda836eL, 0x81be16cdL, 0xf6b9265bL, 0x6fb077e1L,
	97	0x18b74777L, 0x88085ae6L, 0xff0f6a70L, 0x66063bcaL, 0x11010b5cL,
	98	0x8f659effL, 0xf862ae69L, 0x616bffd3L, 0x166ccf45L, 0xa00ae278L,
	99	0xd70dd2eeL, 0x4e048354L, 0x3903b3c2L, 0xa7672661L, 0xd06016f7L,
	100	0x4969474dL, 0x3e6e77dbL, 0xaed16a4aL, 0xd9d65adcL, 0x40df0b66L,
	101	0x37d83bf0L, 0xa9bcae53L, 0xdebb9ec5L, 0x47b2cf7fL, 0x30b5ffe9L,
	102	0xbdbdf21cL, 0xcabac28aL, 0x53b39330L, 0x24b4a3a6L, 0xbad03605L,
	103	0xcdd70693L, 0x54de5729L, 0x23d967bfL, 0xb3667a2eL, 0xc4614ab8L,
	104	0x5d681b02L, 0x2a6f2b94L, 0xb40bbe37L, 0xc30c8ea1L, 0x5a05df1bL,
	105	0x2d02ef8dL
	106	};
8efc0c15	107
	108	/* Return a 32-bit CRC of the contents of the buffer. */
	109
5260325f	110	unsigned int
2e73a022	111	ssh_crc32(const unsigned char *s, unsigned int len)
8efc0c15	112	{
5260325f	113	unsigned int i;
	114	unsigned int crc32val;
	115
	116	crc32val = 0;
	117	for (i = 0; i < len; i ++) {
	118	crc32val = crc32_tab[(crc32val ^ s[i]) & 0xff] ^ (crc32val >> 8);
	119	}
	120	return crc32val;
8efc0c15	121	}