rockbox/firmware/common/crc32.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2003 Jörg Hohensohn [IDC]Dragon
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

/* Code copied from firmware_flash plugin. */

#include "crc32.h"
#include "config.h"

/* Tool function to calculate a CRC32 across some buffer */
/* third argument is either 0xFFFFFFFF to start or value from last piece */
/* speed optimized version */
#ifdef CRC32_FAST
uint32_t crc_32(const void *src, uint32_t len, uint32_t crc32)
{
    const unsigned char *buf = (const unsigned char *)src;

    /* polynomial 0x04C11DB7 - generated with help from pycrc (https://pycrc.org/index.html) */
    static const unsigned crc32_lookup[256] = {
        0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
        0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61, 0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
        0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
        0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
        0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039, 0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
        0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
        0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
        0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1, 0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
        0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
        0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
        0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde, 0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
        0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
        0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
        0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6, 0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
        0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
        0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
        0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637, 0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
        0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
        0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
        0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff, 0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
        0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
        0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
        0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7, 0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
        0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
        0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
        0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8, 0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
        0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
        0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
        0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0, 0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
        0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
        0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
        0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668, 0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
    };

    while (len--) {
        crc32 = (crc32_lookup[((crc32 >> 24) ^ *buf)] ^ (crc32 << 8));
        buf++;
    }

    return crc32;
}
#endif

/* Tool function to calculate a CRC32 across some buffer */
/* third argument is either 0xFFFFFFFF to start or value from last piece */
/* space optimized version */
#ifndef CRC32_FAST
uint32_t crc_32(const void *src, uint32_t len, uint32_t crc32)
{
    const unsigned char *buf = (const unsigned char *)src;
    
    /* CCITT standard polynomial 0x04C11DB7 */
    static const unsigned crc32_lookup[16] =
    {   /* lookup table for 4 bits at a time is affordable */
        0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9,
        0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005,
        0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61,
        0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD
    };

    unsigned char byte;
    uint32_t t;

    while (len--)
    {
        byte = *buf++; /* get one byte of data */

        /* upper nibble of our data */
        t = crc32 >> 28; /* extract the 4 most significant bits */
        t ^= byte >> 4; /* XOR in 4 bits of data into the extracted bits */
        crc32 <<= 4; /* shift the CRC register left 4 bits */
        crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */

        /* lower nibble of our data */
        t = crc32 >> 28; /* extract the 4 most significant bits */
        t ^= byte & 0x0F; /* XOR in 4 bits of data into the extracted bits */
        crc32 <<= 4; /* shift the CRC register left 4 bits */
        crc32 ^= crc32_lookup[t]; /* do the table lookup and XOR the result */
    }

    return crc32;
}
#endif

/* crc_32r (derived from tinf crc32 which was taken from zlib)
 * CRC32 algorithm taken from the zlib source, which is
 * Copyright (C) 1995-1998 Jean-loup Gailly and Mark Adler
 */

/* Tool function to calculate a CRC32 (reversed polynomial) across some buffer */
/* third argument is either the starting value or value from last piece */
uint32_t crc_32r(const void *src, uint32_t len, uint32_t crc32)
{
    const unsigned char* buf = src;

    /* reversed polynomial from other crc32 function -- 0xEDB88320 */
    static const unsigned crc32_lookup[16] =
    {
        0x00000000, 0x1DB71064, 0x3B6E20C8, 0x26D930AC,
        0x76DC4190, 0x6B6B51F4, 0x4DB26158, 0x5005713C,
        0xEDB88320, 0xF00F9344, 0xD6D6A3E8, 0xCB61B38C,
        0x9B64C2B0, 0x86D3D2D4, 0xA00AE278, 0xBDBDF21C
    };

    for(uint32_t i = 0; i < len; i++)
    {
        crc32 ^= buf[i];
        crc32 = crc32_lookup[crc32 & 0x0F] ^ (crc32 >> 4);
        crc32 = crc32_lookup[crc32 & 0x0F] ^ (crc32 >> 4);
    }

    return crc32;
}