u-boot - environment - CRC32

Overview

这里简单提一下environment中使用的CRC32算法，可以作为其他项目计算CRC32时的源码参考。

Source Codes Location

include/u-boot/crc.h
lib/crc32.c

这里仅用到如下两个接口：

uint32_t crc32 (uint32_t, const unsigned char *, uint);
uint32_t crc32_no_comp (uint32_t, const unsigned char *, uint);

解耦版本

这里把以上代码修改后，可以放到其他项目中使用。文件为crc.h, crc32.c，测试驱动文件为main.c。

crc.h

/*
 * (C) Copyright 2009
 * Marvell Semiconductor <www.marvell.com>
 * Written-by: Prafulla Wadaskar <[email protected]>
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#ifndef _UBOOT_CRC_H
#define _UBOOT_CRC_H

#include <stdint.h>

typedef uint32_t uint;
typedef uint32_t uInt;
typedef uint32_t uLong;
typedef unsigned char Byte;
typedef unsigned char Bytef;

/* lib/crc8.c */
//unsigned int crc8(unsigned int crc_start, const unsigned char *vptr, int len);

/* lib/crc32.c */
uint32_t crc32 (uint32_t, const unsigned char *, uint);
//uint32_t crc32_wd (uint32_t, const unsigned char *, uint, uint);
uint32_t crc32_no_comp (uint32_t, const unsigned char *, uint);

/**
 * crc32_wd_buf - Perform CRC32 on a buffer and return result in buffer
 *
 * @input:  Input buffer
 * @ilen:   Input buffer length
 * @output: Place to put checksum result (4 bytes)
 * @chunk_sz:   Trigger watchdog after processing this many bytes
 */
//void crc32_wd_buf(const unsigned char *input, uint ilen,
//          unsigned char *output, uint chunk_sz);

#endif /* _UBOOT_CRC_H */

crc32.c

/*
 * This file is derived from crc32.c from the zlib-1.1.3 distribution
 * by Jean-loup Gailly and Mark Adler.
 */

/* crc32.c -- compute the CRC-32 of a data stream
 * Copyright (C) 1995-1998 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

//#ifdef USE_HOSTCC
//#include <arpa/inet.h>
//#else
//#include <common.h>
//#endif
//#include <compiler.h>
//#include <u-boot/crc.h>
#include <unistd.h>
#include "crc.h"

//#if defined(CONFIG_HW_WATCHDOG) || defined(CONFIG_WATCHDOG)
//#include <watchdog.h>
//#endif
//#include "u-boot/zlib.h"

#define local static
#define ZEXPORT /* empty */

// Little endian is used here.
#define __BYTE_ORDER 1
#define __LITTLE_ENDIAN 1
#define DYNAMIC_CRC_TABLE

# define cpu_to_le32(x)   (x)
# define le32_to_cpu(x)   (x)

#define tole(x) cpu_to_le32(x)

#ifdef DYNAMIC_CRC_TABLE
#define STDC

#ifndef OF /* function prototypes */
#  ifdef STDC
#    define OF(args)  args
#  else
#    define OF(args)  ()
#  endif
#endif

local int crc_table_empty = 1;
local uint32_t crc_table[256];
local void make_crc_table OF((void));

/*
  Generate a table for a byte-wise 32-bit CRC calculation on the 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.

  Polynomials over GF(2) are represented in binary, one bit per coefficient,
  with the lowest powers in the most significant bit.  Then adding polynomials
  is just exclusive-or, and multiplying a polynomial by x is a right shift by
  one.  If we call the above polynomial p, and represent a byte as the
  polynomial q, also with the lowest power in the most significant bit (so the
  byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
  where a mod b means the remainder after dividing a by b.

  This calculation is done using the shift-register method of multiplying and
  taking the remainder.  The register is initialized to zero, and for each
  incoming bit, x^32 is added mod p to the register if the bit is a one (where
  x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
  x (which is shifting right by one and adding x^32 mod p if the bit shifted
  out is a one).  We start with the highest power (least significant bit) of
  q and repeat for all eight bits of q.

  The table is simply the CRC of all possible eight bit values.  This is all
  the information needed to generate CRC's on data a byte at a time for all
  combinations of CRC register values and incoming bytes.
*/
local void make_crc_table()
{
  uint32_t c;
  int n, k;
  uLong poly;       /* polynomial exclusive-or pattern */
  /* terms of polynomial defining this crc (except x^32): */
  static const Byte p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};

  /* make exclusive-or pattern from polynomial (0xedb88320L) */
  poly = 0L;
  for (n = 0; n < sizeof(p)/sizeof(Byte); n++)
    poly |= 1L << (31 - p[n]);

  for (n = 0; n < 256; n++)
  {
    c = (uLong)n;
    for (k = 0; k < 8; k++)
      c = c & 1 ? poly ^ (c >> 1) : c >> 1;
    crc_table[n] = tole(c);
  }
  crc_table_empty = 0;
}
#else
/* ========================================================================
 * Table of CRC-32's of all single-byte values (made by make_crc_table)
 */

local const uint32_t crc_table[256] = {
tole(0x00000000L), tole(0x77073096L), tole(0xee0e612cL), tole(0x990951baL),
tole(0x076dc419L), tole(0x706af48fL), tole(0xe963a535L), tole(0x9e6495a3L),
tole(0x0edb8832L), tole(0x79dcb8a4L), tole(0xe0d5e91eL), tole(0x97d2d988L),
tole(0x09b64c2bL), tole(0x7eb17cbdL), tole(0xe7b82d07L), tole(0x90bf1d91L),
tole(0x1db71064L), tole(0x6ab020f2L), tole(0xf3b97148L), tole(0x84be41deL),
tole(0x1adad47dL), tole(0x6ddde4ebL), tole(0xf4d4b551L), tole(0x83d385c7L),
tole(0x136c9856L), tole(0x646ba8c0L), tole(0xfd62f97aL), tole(0x8a65c9ecL),
tole(0x14015c4fL), tole(0x63066cd9L), tole(0xfa0f3d63L), tole(0x8d080df5L),
tole(0x3b6e20c8L), tole(0x4c69105eL), tole(0xd56041e4L), tole(0xa2677172L),
tole(0x3c03e4d1L), tole(0x4b04d447L), tole(0xd20d85fdL), tole(0xa50ab56bL),
tole(0x35b5a8faL), tole(0x42b2986cL), tole(0xdbbbc9d6L), tole(0xacbcf940L),
tole(0x32d86ce3L), tole(0x45df5c75L), tole(0xdcd60dcfL), tole(0xabd13d59L),
tole(0x26d930acL), tole(0x51de003aL), tole(0xc8d75180L), tole(0xbfd06116L),
tole(0x21b4f4b5L), tole(0x56b3c423L), tole(0xcfba9599L), tole(0xb8bda50fL),
tole(0x2802b89eL), tole(0x5f058808L), tole(0xc60cd9b2L), tole(0xb10be924L),
tole(0x2f6f7c87L), tole(0x58684c11L), tole(0xc1611dabL), tole(0xb6662d3dL),
tole(0x76dc4190L), tole(0x01db7106L), tole(0x98d220bcL), tole(0xefd5102aL),
tole(0x71b18589L), tole(0x06b6b51fL), tole(0x9fbfe4a5L), tole(0xe8b8d433L),
tole(0x7807c9a2L), tole(0x0f00f934L), tole(0x9609a88eL), tole(0xe10e9818L),
tole(0x7f6a0dbbL), tole(0x086d3d2dL), tole(0x91646c97L), tole(0xe6635c01L),
tole(0x6b6b51f4L), tole(0x1c6c6162L), tole(0x856530d8L), tole(0xf262004eL),
tole(0x6c0695edL), tole(0x1b01a57bL), tole(0x8208f4c1L), tole(0xf50fc457L),
tole(0x65b0d9c6L), tole(0x12b7e950L), tole(0x8bbeb8eaL), tole(0xfcb9887cL),
tole(0x62dd1ddfL), tole(0x15da2d49L), tole(0x8cd37cf3L), tole(0xfbd44c65L),
tole(0x4db26158L), tole(0x3ab551ceL), tole(0xa3bc0074L), tole(0xd4bb30e2L),
tole(0x4adfa541L), tole(0x3dd895d7L), tole(0xa4d1c46dL), tole(0xd3d6f4fbL),
tole(0x4369e96aL), tole(0x346ed9fcL), tole(0xad678846L), tole(0xda60b8d0L),
tole(0x44042d73L), tole(0x33031de5L), tole(0xaa0a4c5fL), tole(0xdd0d7cc9L),
tole(0x5005713cL), tole(0x270241aaL), tole(0xbe0b1010L), tole(0xc90c2086L),
tole(0x5768b525L), tole(0x206f85b3L), tole(0xb966d409L), tole(0xce61e49fL),
tole(0x5edef90eL), tole(0x29d9c998L), tole(0xb0d09822L), tole(0xc7d7a8b4L),
tole(0x59b33d17L), tole(0x2eb40d81L), tole(0xb7bd5c3bL), tole(0xc0ba6cadL),
tole(0xedb88320L), tole(0x9abfb3b6L), tole(0x03b6e20cL), tole(0x74b1d29aL),
tole(0xead54739L), tole(0x9dd277afL), tole(0x04db2615L), tole(0x73dc1683L),
tole(0xe3630b12L), tole(0x94643b84L), tole(0x0d6d6a3eL), tole(0x7a6a5aa8L),
tole(0xe40ecf0bL), tole(0x9309ff9dL), tole(0x0a00ae27L), tole(0x7d079eb1L),
tole(0xf00f9344L), tole(0x8708a3d2L), tole(0x1e01f268L), tole(0x6906c2feL),
tole(0xf762575dL), tole(0x806567cbL), tole(0x196c3671L), tole(0x6e6b06e7L),
tole(0xfed41b76L), tole(0x89d32be0L), tole(0x10da7a5aL), tole(0x67dd4accL),
tole(0xf9b9df6fL), tole(0x8ebeeff9L), tole(0x17b7be43L), tole(0x60b08ed5L),
tole(0xd6d6a3e8L), tole(0xa1d1937eL), tole(0x38d8c2c4L), tole(0x4fdff252L),
tole(0xd1bb67f1L), tole(0xa6bc5767L), tole(0x3fb506ddL), tole(0x48b2364bL),
tole(0xd80d2bdaL), tole(0xaf0a1b4cL), tole(0x36034af6L), tole(0x41047a60L),
tole(0xdf60efc3L), tole(0xa867df55L), tole(0x316e8eefL), tole(0x4669be79L),
tole(0xcb61b38cL), tole(0xbc66831aL), tole(0x256fd2a0L), tole(0x5268e236L),
tole(0xcc0c7795L), tole(0xbb0b4703L), tole(0x220216b9L), tole(0x5505262fL),
tole(0xc5ba3bbeL), tole(0xb2bd0b28L), tole(0x2bb45a92L), tole(0x5cb36a04L),
tole(0xc2d7ffa7L), tole(0xb5d0cf31L), tole(0x2cd99e8bL), tole(0x5bdeae1dL),
tole(0x9b64c2b0L), tole(0xec63f226L), tole(0x756aa39cL), tole(0x026d930aL),
tole(0x9c0906a9L), tole(0xeb0e363fL), tole(0x72076785L), tole(0x05005713L),
tole(0x95bf4a82L), tole(0xe2b87a14L), tole(0x7bb12baeL), tole(0x0cb61b38L),
tole(0x92d28e9bL), tole(0xe5d5be0dL), tole(0x7cdcefb7L), tole(0x0bdbdf21L),
tole(0x86d3d2d4L), tole(0xf1d4e242L), tole(0x68ddb3f8L), tole(0x1fda836eL),
tole(0x81be16cdL), tole(0xf6b9265bL), tole(0x6fb077e1L), tole(0x18b74777L),
tole(0x88085ae6L), tole(0xff0f6a70L), tole(0x66063bcaL), tole(0x11010b5cL),
tole(0x8f659effL), tole(0xf862ae69L), tole(0x616bffd3L), tole(0x166ccf45L),
tole(0xa00ae278L), tole(0xd70dd2eeL), tole(0x4e048354L), tole(0x3903b3c2L),
tole(0xa7672661L), tole(0xd06016f7L), tole(0x4969474dL), tole(0x3e6e77dbL),
tole(0xaed16a4aL), tole(0xd9d65adcL), tole(0x40df0b66L), tole(0x37d83bf0L),
tole(0xa9bcae53L), tole(0xdebb9ec5L), tole(0x47b2cf7fL), tole(0x30b5ffe9L),
tole(0xbdbdf21cL), tole(0xcabac28aL), tole(0x53b39330L), tole(0x24b4a3a6L),
tole(0xbad03605L), tole(0xcdd70693L), tole(0x54de5729L), tole(0x23d967bfL),
tole(0xb3667a2eL), tole(0xc4614ab8L), tole(0x5d681b02L), tole(0x2a6f2b94L),
tole(0xb40bbe37L), tole(0xc30c8ea1L), tole(0x5a05df1bL), tole(0x2d02ef8dL)
};
#endif

#if 0
/* =========================================================================
 * This function can be used by asm versions of crc32()
 */
const uint32_t * ZEXPORT get_crc_table()
{
#ifdef DYNAMIC_CRC_TABLE
  if (crc_table_empty) make_crc_table();
#endif
  return (const uint32_t *)crc_table;
}
#endif

/* ========================================================================= */
# if __BYTE_ORDER == __LITTLE_ENDIAN
#  define DO_CRC(x) crc = tab[(crc ^ (x)) & 255] ^ (crc >> 8)
# else
#  define DO_CRC(x) crc = tab[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
# endif

/* ========================================================================= */

/* No ones complement version. JFFS2 (and other things ?)
 * don't use ones compliment in their CRC calculations.
 */
uint32_t ZEXPORT crc32_no_comp(uint32_t crc, const Bytef *buf, uInt len)
{
    const uint32_t *tab = crc_table;
    const uint32_t *b =(const uint32_t *)buf;
    size_t rem_len;
#ifdef DYNAMIC_CRC_TABLE
    if (crc_table_empty)
      make_crc_table();
#endif
    crc = cpu_to_le32(crc);
    /* Align it */
    if (((long)b) & 3 && len) {
     uint8_t *p = (uint8_t *)b;
     do {
          DO_CRC(*p++);
     } while ((--len) && ((long)p)&3);
     b = (uint32_t *)p;
    }

    rem_len = len & 3;
    len = len >> 2;
    for (--b; len; --len) {
     /* load data 32 bits wide, xor data 32 bits wide. */
     crc ^= *++b; /* use pre increment for speed */
     DO_CRC(0);
     DO_CRC(0);
     DO_CRC(0);
     DO_CRC(0);
    }
    len = rem_len;
    /* And the last few bytes */
    if (len) {
     uint8_t *p = (uint8_t *)(b + 1) - 1;
     do {
          DO_CRC(*++p); /* use pre increment for speed */
     } while (--len);
    }

    return le32_to_cpu(crc);
}
#undef DO_CRC

uint32_t ZEXPORT crc32 (uint32_t crc, const Bytef *p, uInt len)
{
     return crc32_no_comp(crc ^ 0xffffffffL, p, len) ^ 0xffffffffL;
}

/*
 * Calculate the crc32 checksum triggering the watchdog every 'chunk_sz' bytes
 * of input.
 */
/*uint32_t ZEXPORT crc32_wd (uint32_t crc,
               const unsigned char *buf,
               uInt len, uInt chunk_sz)
{
#if defined(CONFIG_HW_WATCHDOG) || defined(CONFIG_WATCHDOG)
    const unsigned char *end, *curr;
    int chunk;

    curr = buf;
    end = buf + len;
    while (curr < end) {
        chunk = end - curr;
        if (chunk > chunk_sz)
            chunk = chunk_sz;
        crc = crc32 (crc, curr, chunk);
        curr += chunk;
        WATCHDOG_RESET ();
    }
#else
    crc = crc32 (crc, buf, len);
#endif

    return crc;
}

void crc32_wd_buf(const unsigned char *input, unsigned int ilen,
        unsigned char *output, unsigned int chunk_sz)
{
    uint32_t crc;

    crc = crc32_wd(0, input, ilen, chunk_sz);
    crc = htonl(crc);
    memcpy(output, &crc, sizeof(crc));
}*/

main.c

#include <stdio.h>
#include <errno.h>
#include <string.h>

#include "crc.h"

int main(int argc, const char *argv[])
{
    if (argc != 2) {
        printf("Usage: %s filename\n", argv[0]);
        return 1;
    }

    FILE* fp = fopen(argv[1], "rb");
    if (NULL == fp) {
        printf("ERROR: %s\n", strerror(errno));
        return 1;
    }

    unsigned char buffer[1024] = {0};
    unsigned int count = 0;
    uint32_t crc = 0;

    for (;;) {
        count = fread(buffer, 1, 1024, fp);
        if (count == 0) break;

        crc = crc32(crc, buffer, count);
    }

    fclose(fp);

    printf("%08x\n", crc);

    return 0;
}

运行&验证

这里用Linux的crc32命令对以上代码进行验证。

$ gcc main.c crc32.c 
$ ./a.out main.c 
39a7365c
$ crc32 main.c
39a7365c
$