/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "lib/misc/lib.h"

#include "lib/misc/crc.h"
#include "lib/mm/xlate.h"

/*
 * CRC-32 byte lookup table generated by crc_gen.c
 *
 * Precomputed lookup table for CRC computed with 0xedb88320 polynomial.
 */
static const uint32_t _crctab[] = {
	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 __x86_64__
/*
 * Note that the CRC-32 checksum is merely used for error detection in
 * transmission and storage. It is not intended to guard against the malicious
 * modification of files (i.e., it is not a cryptographic hash). !!!
 *
 * This code is based on zlib code from:
 *
 * https://github.com/vlastavesely/crc32sum
 * https://github.com/chromium/chromium/blob/master/third_party/zlib/
 *
 * SPDX-License-Identifier: GPL-2.0
 */


/*
 * ATM Use this code only for X86_64 arch where it was tested
 * TODO: check if it speeds also non X86_64 arch
 */

static unsigned int _crc32_lookup[16][256] = { { 0 } };

static void _initialise_crc32(void)
{
	unsigned int i, j;

	if (_crc32_lookup[0][1])
		return;

	for (i = 0; i < 256; i++)
		_crc32_lookup[0][i] = _crctab[i];

	for (i = 0; i < 256; i++)
		for (j = 1; j < 16; j++)
			_crc32_lookup[j][i] = (_crc32_lookup[j - 1][i] >> 8) ^
				_crc32_lookup[0][_crc32_lookup[j - 1][i] & 0xff];
}

#ifndef DEBUG_CRC32
uint32_t calc_crc(uint32_t initial, const uint8_t *buf, uint32_t size)
#else
static uint32_t _calc_crc_new(uint32_t initial, const uint8_t *buf, uint32_t size)
#endif
{
	const uint32_t *ptr = (const uint32_t *) buf;
	uint32_t a, b, c, d;
	uint32_t crc = initial;

	_initialise_crc32();

	for (;size >= 16; size -= 16) {
		a = htole32(*ptr++) ^ crc;
		b = htole32(*ptr++);
		c = htole32(*ptr++);
		d = htole32(*ptr++);

		crc = _crc32_lookup[ 0][(d >> 24) & 0xff] ^
		      _crc32_lookup[ 1][(d >> 16) & 0xff] ^
		      _crc32_lookup[ 2][(d >>  8) & 0xff] ^
		      _crc32_lookup[ 3][ d        & 0xff] ^
		      _crc32_lookup[ 4][(c >> 24) & 0xff] ^
		      _crc32_lookup[ 5][(c >> 16) & 0xff] ^
		      _crc32_lookup[ 6][(c >>  8) & 0xff] ^
		      _crc32_lookup[ 7][ c        & 0xff] ^
		      _crc32_lookup[ 8][(b >> 24) & 0xff] ^
		      _crc32_lookup[ 9][(b >> 16) & 0xff] ^
		      _crc32_lookup[10][(b >>  8) & 0xff] ^
		      _crc32_lookup[11][ b        & 0xff] ^
		      _crc32_lookup[12][(a >> 24) & 0xff] ^
		      _crc32_lookup[13][(a >> 16) & 0xff] ^
		      _crc32_lookup[14][(a >>  8) & 0xff] ^
		      _crc32_lookup[15][ a        & 0xff];
	}

	buf = (const uint8_t *) ptr;

	while (size--)
		crc = _crc32_lookup[0][((unsigned char) crc ^ *(buf++))] ^ (crc >> 8);

	return crc;
}

#else  // __x86_64__

/* Calculate an endian-independent CRC of supplied buffer */
#ifndef DEBUG_CRC32
uint32_t calc_crc(uint32_t initial, const uint8_t *buf, uint32_t size)
#else
static uint32_t _calc_crc_new(uint32_t initial, const uint8_t *buf, uint32_t size)
#endif
{
	const uint32_t *start = (const uint32_t *) buf;
	const uint32_t *end = (const uint32_t *) (buf + (size & 0xfffffffc));
	uint32_t crc = initial;

	/* Process 4 bytes per iteration */
	while (start < end) {
		crc = crc ^ htole32(*start++);
		crc = _crctab[crc & 0xff] ^ crc >> 8;
		crc = _crctab[crc & 0xff] ^ crc >> 8;
		crc = _crctab[crc & 0xff] ^ crc >> 8;
		crc = _crctab[crc & 0xff] ^ crc >> 8;
	}

	/* Process any bytes left over */
	buf = (const uint8_t *) start;
	size = size & 0x3;
	while (size--) {
		crc = crc ^ *buf++;
		crc = _crctab[crc & 0xff] ^ crc >> 8;
	}

	return crc;
}

#endif // __x86_64__

#ifdef DEBUG_CRC32
static uint32_t _calc_crc_old(uint32_t initial, const uint8_t *buf, uint32_t size)
{
	static const uint32_t _crctab[] = {
		0x00000000, 0x1db71064, 0x3b6e20c8, 0x26d930ac,
		0x76dc4190, 0x6b6b51f4, 0x4db26158, 0x5005713c,
		0xedb88320, 0xf00f9344, 0xd6d6a3e8, 0xcb61b38c,
		0x9b64c2b0, 0x86d3d2d4, 0xa00ae278, 0xbdbdf21c
	};
	uint32_t i, crc = initial;

	for (i = 0; i < size; i++) {
		crc ^= *buf++;
		crc = (crc >> 4) ^ _crctab[crc & 0xf];
		crc = (crc >> 4) ^ _crctab[crc & 0xf];
	}
	return crc;
}

uint32_t calc_crc(uint32_t initial, const uint8_t *buf, uint32_t size)
{
	uint32_t new_crc = _calc_crc_new(initial, buf, size);
	uint32_t old_crc = _calc_crc_old(initial, buf, size);

	if (new_crc != old_crc)
		log_error(INTERNAL_ERROR "Old and new crc32 algorithms mismatch: 0x%08x != 0x%08x", old_crc, new_crc);

	return old_crc;
}

#endif /* DEBUG_CRC32 */
