user-0 提问: 硬件CRC校验和软件CRC校验的问题

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user: user-1
content: 参考zlib\crc32.c: /* crc32.c -- compute the CRC-32 of a data stream  * Copyright (C) 1995-2006, 2010 Mark Adler  * For conditions of distribution and use, see copyright notice in zlib.h  *  * Thanks to Rodney Brown <rbrown64@csc.com.au> for his contribution of faster  * CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing  * tables for updating the shift register in one step with three exclusive-ors  * instead of four steps with four exclusive-ors.  This results in about a  * factor of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3.  */  /* @(#) $Id$ */  /*   Note on the use of DYNAMIC_CRC_TABLE: there is no mutex or semaphore   protection on the static variables used to control the first-use generation   of the crc tables.  Therefore, if you #define DYNAMIC_CRC_TABLE, you should   first call get_crc_table() to initialize the tables before allowing more than   one thread to use crc32().  */  #ifdef MAKECRCH #  include <stdio.h> #  ifndef DYNAMIC_CRC_TABLE #    define DYNAMIC_CRC_TABLE #  endif /* !DYNAMIC_CRC_TABLE */ #endif /* MAKECRCH */  #include "zutil.h"      /* for STDC and FAR definitions */  #define local static  /* Find a four-byte integer type for crc32_little() and crc32_big(). */ #ifndef NOBYFOUR #  ifdef STDC           /* need ANSI C limits.h to determine sizes */ #    include <limits.h> #    define BYFOUR #    if (UINT_MAX == 0xffffffffUL)        typedef unsigned int u4; #    else #      if (ULONG_MAX == 0xffffffffUL)          typedef unsigned long u4; #      else #        if (USHRT_MAX == 0xffffffffUL)            typedef unsigned short u4; #        else #          undef BYFOUR     /* can't find a four-byte integer type! */ #        endif #      endif #    endif #  endif /* STDC */ #endif /* !NOBYFOUR */  /* Definitions for doing the crc four data bytes at a time. */ #ifdef BYFOUR #  define REV(w) ((((w)>>24)&0xff)+(((w)>>8)&0xff00)+ \                 (((w)&0xff00)<<8)+(((w)&0xff)<<24))    local unsigned long crc32_little OF((unsigned long,                         const unsigned char FAR *, unsigned));    local unsigned long crc32_big OF((unsigned long,                         const unsigned char FAR *, unsigned)); #  define TBLS 8 #else #  define TBLS 1 #endif /* BYFOUR */  /* Local functions for crc concatenation */ local unsigned long gf2_matrix_times OF((unsigned long *mat,                                          unsigned long vec)); local void gf2_matrix_square OF((unsigned long *square, unsigned long *mat)); local uLong crc32_combine_(uLong crc1, uLong crc2, z_off64_t len2);   #ifdef DYNAMIC_CRC_TABLE  local volatile int crc_table_empty = 1; local unsigned long FAR crc_table[TBLS][256]; local void make_crc_table OF((void)); #ifdef MAKECRCH    local void write_table OF((FILE *, const unsigned long FAR *)); #endif /* MAKECRCH */ /*   Generate tables 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 first table is simply the CRC of all possible eight bit values.  This is   all the information needed to generate CRCs on data a byte at a time for all   combinations of CRC register values and incoming bytes.  The remaining tables   allow for word-at-a-time CRC calculation for both big-endian and little-   endian machines, where a word is four bytes. */ local void make_crc_table() {     unsigned long c;     int n, k;     unsigned long poly;                 /* polynomial exclusive-or pattern */     /* terms of polynomial defining this crc (except x^32): */     static volatile int first = 1;      /* flag to limit concurrent making */     static const unsigned char p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};      /* See if another task is already doing this (not thread-safe, but better        than nothing -- significantly reduces duration of vulnerability in        case the advice about DYNAMIC_CRC_TABLE is ignored) */     if (first) {         first = 0;          /* make exclusive-or pattern from polynomial (0xedb88320UL) */         poly = 0UL;         for (n = 0; n < sizeof(p)/sizeof(unsigned char); n++)             poly |= 1UL << (31 - p[n]);          /* generate a crc for every 8-bit value */         for (n = 0; n < 256; n++) {             c = (unsigned long)n;             for (k = 0; k < 8; k++)                 c = c & 1 ? poly ^ (c >> 1) : c >> 1;             crc_table[0][n] = c;         }  #ifdef BYFOUR         /* generate crc for each value followed by one, two, and three zeros,            and then the byte reversal of those as well as the first table */         for (n = 0; n < 256; n++) {             c = crc_table[0][n];             crc_table[4][n] = REV(c);             for (k = 1; k < 4; k++) {                 c = crc_table[0][c & 0xff] ^ (c >> 8);                 crc_table[k][n] = c;                 crc_table[k + 4][n] = REV(c);             }         } #endif /* BYFOUR */          crc_table_empty = 0;     }     else {      /* not first */         /* wait for the other guy to finish (not efficient, but rare) */         while (crc_table_empty)             ;     }  #ifdef MAKECRCH     /* write out CRC tables to crc32.h */     {         FILE *out;          out = fopen("crc32.h", "w");         if (out == NULL) return;         fprintf(out, "/* crc32.h -- tables for rapid CRC calculation\n");         fprintf(out, " * Generated automatically by crc32.c\n */\n\n");         fprintf(out, "local const unsigned long FAR ");         fprintf(out, "crc_table[TBLS][256] =\n{\n  {\n");         write_table(out, crc_table[0]); #  ifdef BYFOUR         fprintf(out, "#ifdef BYFOUR\n");         for (k = 1; k < 8; k++) {             fprintf(out, "  },\n  {\n");             write_table(out, crc_table[k]);         }         fprintf(out, "#endif\n"); #  endif /* BYFOUR */         fprintf(out, "  }\n};\n");         fclose(out);     } #endif /* MAKECRCH */ }  #ifdef MAKECRCH local void write_table(out, table)     FILE *out;     const unsigned long FAR *table; {     int n;      for (n = 0; n < 256; n++)         fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : "    ", table[n],                 n == 255 ? "\n" : (n % 5 == 4 ? ",\n" : ", ")); } #endif /* MAKECRCH */  #else /* !DYNAMIC_CRC_TABLE */ /* ========================================================================  * Tables of CRC-32s of all single-byte values, made by make_crc_table().  */ #include "crc32.h" #endif /* DYNAMIC_CRC_TABLE */  /* =========================================================================  * This function can be used by asm versions of crc32()  */ const unsigned long FAR * ZEXPORT get_crc_table() { #ifdef DYNAMIC_CRC_TABLE     if (crc_table_empty)         make_crc_table(); #endif /* DYNAMIC_CRC_TABLE */     return (const unsigned long FAR *)crc_table; }  /* ========================================================================= */ #define DO1 crc = crc_table[0][((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8) #define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1  /* ========================================================================= */ unsigned long ZEXPORT crc32(crc, buf, len)     unsigned long crc;     const unsigned char FAR *buf;     uInt len; {     if (buf == Z_NULL) return 0UL;  #ifdef DYNAMIC_CRC_TABLE     if (crc_table_empty)         make_crc_table(); #endif /* DYNAMIC_CRC_TABLE */  #ifdef BYFOUR     if (sizeof(void *) == sizeof(ptrdiff_t)) {         u4 endian;          endian = 1;         if (*((unsigned char *)(&endian)))             return crc32_little(crc, buf, len);         else             return crc32_big(crc, buf, len);     } #endif /* BYFOUR */     crc = crc ^ 0xffffffffUL;     while (len >= 8) {         DO8;         len -= 8;     }     if (len) do {         DO1;     } while (--len);     return crc ^ 0xffffffffUL; }  #ifdef BYFOUR  /* ========================================================================= */ #define DOLIT4 c ^= *buf4++; \         c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \             crc_table[1][(c >> 16) & 0xff] ^ crc_table[0][c >> 24] #define DOLIT32 DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4  /* ========================================================================= */ local unsigned long crc32_little(crc, buf, len)     unsigned long crc;     const unsigned char FAR *buf;     unsigned len; {     register u4 c;     register const u4 FAR *buf4;      c = (u4)crc;     c = ~c;     while (len && ((ptrdiff_t)buf & 3)) {         c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);         len--;     }      buf4 = (const u4 FAR *)(const void FAR *)buf;     while (len >= 32) {         DOLIT32;         len -= 32;     }     while (len >= 4) {         DOLIT4;         len -= 4;     }     buf = (const unsigned char FAR *)buf4;      if (len) do {         c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);     } while (--len);     c = ~c;     return (unsigned long)c; }  /* ========================================================================= */ #define DOBIG4 c ^= *++buf4; \         c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \             crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24] #define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4  /* ========================================================================= */ local unsigned long crc32_big(crc, buf, len)     unsigned long crc;     const unsigned char FAR *buf;     unsigned len; {     register u4 c;     register const u4 FAR *buf4;      c = REV((u4)crc);     c = ~c;     while (len && ((ptrdiff_t)buf & 3)) {         c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);         len--;     }      buf4 = (const u4 FAR *)(const void FAR *)buf;     buf4--;     while (len >= 32) {         DOBIG32;         len -= 32;     }     while (len >= 4) {         DOBIG4;         len -= 4;     }     buf4++;     buf = (const unsigned char FAR *)buf4;      if (len) do {         c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);     } while (--len);     c = ~c;     return (unsigned long)(REV(c)); }  #endif /* BYFOUR */  #define GF2_DIM 32      /* dimension of GF(2) vectors (length of CRC) */  /* ========================================================================= */ local unsigned long gf2_matrix_times(mat, vec)     unsigned long *mat;     unsigned long vec; {     unsigned long sum;      sum = 0;     while (vec) {         if (vec & 1)             sum ^= *mat;         vec >>= 1;         mat++;     }     return sum; }  /* ========================================================================= */ local void gf2_matrix_square(square, mat)     unsigned long *square;     unsigned long *mat; {     int n;      for (n = 0; n < GF2_DIM; n++)         square[n] = gf2_matrix_times(mat, mat[n]); }  /* ========================================================================= */ local uLong crc32_combine_(crc1, crc2, len2)     uLong crc1;     uLong crc2;     z_off64_t len2; {     int n;     unsigned long row;     unsigned long even[GF2_DIM];    /* even-power-of-two zeros operator */     unsigned long odd[GF2_DIM];     /* odd-power-of-two zeros operator */      /* degenerate case (also disallow negative lengths) */     if (len2 <= 0)         return crc1;      /* put operator for one zero bit in odd */     odd[0] = 0xedb88320UL;          /* CRC-32 polynomial */     row = 1;     for (n = 1; n < GF2_DIM; n++) {         odd[n] = row;         row <<= 1;     }      /* put operator for two zero bits in even */     gf2_matrix_square(even, odd);      /* put operator for four zero bits in odd */     gf2_matrix_square(odd, even);      /* apply len2 zeros to crc1 (first square will put the operator for one        zero byte, eight zero bits, in even) */     do {         /* apply zeros operator for this bit of len2 */         gf2_matrix_square(even, odd);         if (len2 & 1)             crc1 = gf2_matrix_times(even, crc1);         len2 >>= 1;          /* if no more bits set, then done */         if (len2 == 0)             break;          /* another iteration of the loop with odd and even swapped */         gf2_matrix_square(odd, even);         if (len2 & 1)             crc1 = gf2_matrix_times(odd, crc1);         len2 >>= 1;          /* if no more bits set, then done */     } while (len2 != 0);      /* return combined crc */     crc1 ^= crc2;     return crc1; }  /* ========================================================================= */ uLong ZEXPORT crc32_combine(crc1, crc2, len2)     uLong crc1;     uLong crc2;     z_off_t len2; {     return crc32_combine_(crc1, crc2, len2); }  uLong ZEXPORT crc32_combine64(crc1, crc2, len2)     uLong crc1;     uLong crc2;     z_off64_t len2; {     return crc32_combine_(crc1, crc2, len2); }

user: user-0
content: 谢谢赵4老师！辛苦你了。咱们论坛能不能选择最佳答案呀？

user: user-0
content: 赵4老师，我用devc++软件，C工程，提示找不到zutil.h

user: user-0
content: 赵4老师，这是不是linux的代码呀？太难懂了

user: user-1
content: 你需要看HAL_CRC_Calculate的实现

user: user-0
content: 我看了，这个看不出来的，是硬件CRC，设置好在之后，自动出数。

user: user-2
content: 你的意思是需要一个工具计算出aDataBuffer 对应的crc值吗可以用http://www.ip33.com/crc.html .

user: user-0
content: 谢谢！你理解错了，我想知道计算的过程。比如单片机使用硬件CRC，上位机使用软件CRC，怎么得出和硬件CRC一样的结果。