zlib123/crc32.c
author Ryan C. Gordon <icculus@icculus.org>
Wed, 03 Oct 2018 22:45:05 -0400
branchstable-1.0
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permissions -rw-r--r--
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/* crc32.c -- compute the CRC-32 of a data stream
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 * Copyright (C) 1995-2005 Mark Adler
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 * For conditions of distribution and use, see copyright notice in zlib.h
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 *
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 * Thanks to Rodney Brown <rbrown64@csc.com.au> for his contribution of faster
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 * CRC methods: exclusive-oring 32 bits of data at a time, and pre-computing
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 * tables for updating the shift register in one step with three exclusive-ors
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 * instead of four steps with four exclusive-ors.  This results in about a
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 * factor of two increase in speed on a Power PC G4 (PPC7455) using gcc -O3.
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 */
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/* @(#) $Id$ */
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/*
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  Note on the use of DYNAMIC_CRC_TABLE: there is no mutex or semaphore
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  protection on the static variables used to control the first-use generation
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  of the crc tables.  Therefore, if you #define DYNAMIC_CRC_TABLE, you should
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  first call get_crc_table() to initialize the tables before allowing more than
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  one thread to use crc32().
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 */
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#ifdef MAKECRCH
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#  include <stdio.h>
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#  ifndef DYNAMIC_CRC_TABLE
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#    define DYNAMIC_CRC_TABLE
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#  endif /* !DYNAMIC_CRC_TABLE */
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#endif /* MAKECRCH */
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#include "zutil.h"      /* for STDC and FAR definitions */
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#define local static
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/* Find a four-byte integer type for crc32_little() and crc32_big(). */
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#ifndef NOBYFOUR
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#  ifdef STDC           /* need ANSI C limits.h to determine sizes */
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#    include <limits.h>
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#    define BYFOUR
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#    if (UINT_MAX == 0xffffffffUL)
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       typedef unsigned int u4;
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#    else
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#      if (ULONG_MAX == 0xffffffffUL)
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         typedef unsigned long u4;
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#      else
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#        if (USHRT_MAX == 0xffffffffUL)
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           typedef unsigned short u4;
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#        else
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#          undef BYFOUR     /* can't find a four-byte integer type! */
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#        endif
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#      endif
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#    endif
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#  endif /* STDC */
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#endif /* !NOBYFOUR */
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/* Definitions for doing the crc four data bytes at a time. */
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#ifdef BYFOUR
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#  define REV(w) (((w)>>24)+(((w)>>8)&0xff00)+ \
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                (((w)&0xff00)<<8)+(((w)&0xff)<<24))
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   local unsigned long crc32_little OF((unsigned long,
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                        const unsigned char FAR *, unsigned));
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   local unsigned long crc32_big OF((unsigned long,
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                        const unsigned char FAR *, unsigned));
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#  define TBLS 8
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#else
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#  define TBLS 1
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#endif /* BYFOUR */
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/* Local functions for crc concatenation */
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local unsigned long gf2_matrix_times OF((unsigned long *mat,
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                                         unsigned long vec));
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local void gf2_matrix_square OF((unsigned long *square, unsigned long *mat));
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#ifdef DYNAMIC_CRC_TABLE
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local volatile int crc_table_empty = 1;
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local unsigned long FAR crc_table[TBLS][256];
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local void make_crc_table OF((void));
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#ifdef MAKECRCH
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   local void write_table OF((FILE *, const unsigned long FAR *));
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#endif /* MAKECRCH */
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/*
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  Generate tables for a byte-wise 32-bit CRC calculation on the polynomial:
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  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.
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  Polynomials over GF(2) are represented in binary, one bit per coefficient,
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  with the lowest powers in the most significant bit.  Then adding polynomials
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  is just exclusive-or, and multiplying a polynomial by x is a right shift by
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  one.  If we call the above polynomial p, and represent a byte as the
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  polynomial q, also with the lowest power in the most significant bit (so the
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  byte 0xb1 is the polynomial x^7+x^3+x+1), then the CRC is (q*x^32) mod p,
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  where a mod b means the remainder after dividing a by b.
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  This calculation is done using the shift-register method of multiplying and
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  taking the remainder.  The register is initialized to zero, and for each
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  incoming bit, x^32 is added mod p to the register if the bit is a one (where
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  x^32 mod p is p+x^32 = x^26+...+1), and the register is multiplied mod p by
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  x (which is shifting right by one and adding x^32 mod p if the bit shifted
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  out is a one).  We start with the highest power (least significant bit) of
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  q and repeat for all eight bits of q.
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  The first table is simply the CRC of all possible eight bit values.  This is
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  all the information needed to generate CRCs on data a byte at a time for all
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  combinations of CRC register values and incoming bytes.  The remaining tables
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  allow for word-at-a-time CRC calculation for both big-endian and little-
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  endian machines, where a word is four bytes.
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*/
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local void make_crc_table()
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{
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    unsigned long c;
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    int n, k;
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    unsigned long poly;                 /* polynomial exclusive-or pattern */
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    /* terms of polynomial defining this crc (except x^32): */
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    static volatile int first = 1;      /* flag to limit concurrent making */
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    static const unsigned char p[] = {0,1,2,4,5,7,8,10,11,12,16,22,23,26};
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    /* See if another task is already doing this (not thread-safe, but better
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       than nothing -- significantly reduces duration of vulnerability in
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       case the advice about DYNAMIC_CRC_TABLE is ignored) */
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    if (first) {
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        first = 0;
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        /* make exclusive-or pattern from polynomial (0xedb88320UL) */
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        poly = 0UL;
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        for (n = 0; n < sizeof(p)/sizeof(unsigned char); n++)
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            poly |= 1UL << (31 - p[n]);
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        /* generate a crc for every 8-bit value */
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Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   127
        for (n = 0; n < 256; n++) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   128
            c = (unsigned long)n;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   129
            for (k = 0; k < 8; k++)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   130
                c = c & 1 ? poly ^ (c >> 1) : c >> 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   131
            crc_table[0][n] = c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   132
        }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   133
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   134
#ifdef BYFOUR
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   135
        /* generate crc for each value followed by one, two, and three zeros,
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   136
           and then the byte reversal of those as well as the first table */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   137
        for (n = 0; n < 256; n++) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   138
            c = crc_table[0][n];
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   139
            crc_table[4][n] = REV(c);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   140
            for (k = 1; k < 4; k++) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   141
                c = crc_table[0][c & 0xff] ^ (c >> 8);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   142
                crc_table[k][n] = c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   143
                crc_table[k + 4][n] = REV(c);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   144
            }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   145
        }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   146
#endif /* BYFOUR */
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Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   147
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   148
        crc_table_empty = 0;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   149
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   150
    else {      /* not first */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   151
        /* wait for the other guy to finish (not efficient, but rare) */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   152
        while (crc_table_empty)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   153
            ;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   154
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   155
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   156
#ifdef MAKECRCH
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   157
    /* write out CRC tables to crc32.h */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   158
    {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   159
        FILE *out;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   160
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   161
        out = fopen("crc32.h", "w");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   162
        if (out == NULL) return;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   163
        fprintf(out, "/* crc32.h -- tables for rapid CRC calculation\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   164
        fprintf(out, " * Generated automatically by crc32.c\n */\n\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   165
        fprintf(out, "local const unsigned long FAR ");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   166
        fprintf(out, "crc_table[TBLS][256] =\n{\n  {\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   167
        write_table(out, crc_table[0]);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   168
#  ifdef BYFOUR
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   169
        fprintf(out, "#ifdef BYFOUR\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   170
        for (k = 1; k < 8; k++) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   171
            fprintf(out, "  },\n  {\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   172
            write_table(out, crc_table[k]);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   173
        }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   174
        fprintf(out, "#endif\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   175
#  endif /* BYFOUR */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   176
        fprintf(out, "  }\n};\n");
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   177
        fclose(out);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   178
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   179
#endif /* MAKECRCH */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   180
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   181
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   182
#ifdef MAKECRCH
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   183
local void write_table(out, table)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   184
    FILE *out;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   185
    const unsigned long FAR *table;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   186
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   187
    int n;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   188
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   189
    for (n = 0; n < 256; n++)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   190
        fprintf(out, "%s0x%08lxUL%s", n % 5 ? "" : "    ", table[n],
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   191
                n == 255 ? "\n" : (n % 5 == 4 ? ",\n" : ", "));
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   192
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   193
#endif /* MAKECRCH */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   194
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   195
#else /* !DYNAMIC_CRC_TABLE */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   196
/* ========================================================================
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   197
 * Tables of CRC-32s of all single-byte values, made by make_crc_table().
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   198
 */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   199
#include "crc32.h"
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   200
#endif /* DYNAMIC_CRC_TABLE */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   201
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   202
/* =========================================================================
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   203
 * This function can be used by asm versions of crc32()
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   204
 */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   205
const unsigned long FAR * ZEXPORT get_crc_table()
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   206
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   207
#ifdef DYNAMIC_CRC_TABLE
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   208
    if (crc_table_empty)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   209
        make_crc_table();
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   210
#endif /* DYNAMIC_CRC_TABLE */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   211
    return (const unsigned long FAR *)crc_table;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   212
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   213
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   214
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   215
#define DO1 crc = crc_table[0][((int)crc ^ (*buf++)) & 0xff] ^ (crc >> 8)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   216
#define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   217
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   218
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   219
unsigned long ZEXPORT crc32(crc, buf, len)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   220
    unsigned long crc;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   221
    const unsigned char FAR *buf;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   222
    unsigned len;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   223
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   224
    if (buf == Z_NULL) return 0UL;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   225
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   226
#ifdef DYNAMIC_CRC_TABLE
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   227
    if (crc_table_empty)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   228
        make_crc_table();
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   229
#endif /* DYNAMIC_CRC_TABLE */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   230
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   231
#ifdef BYFOUR
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   232
    if (sizeof(void *) == sizeof(ptrdiff_t)) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   233
        u4 endian;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   234
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   235
        endian = 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   236
        if (*((unsigned char *)(&endian)))
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   237
            return crc32_little(crc, buf, len);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   238
        else
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   239
            return crc32_big(crc, buf, len);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   240
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   241
#endif /* BYFOUR */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   242
    crc = crc ^ 0xffffffffUL;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   243
    while (len >= 8) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   244
        DO8;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   245
        len -= 8;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   246
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   247
    if (len) do {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   248
        DO1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   249
    } while (--len);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   250
    return crc ^ 0xffffffffUL;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   251
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   252
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   253
#ifdef BYFOUR
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   254
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   255
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   256
#define DOLIT4 c ^= *buf4++; \
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   257
        c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   258
            crc_table[1][(c >> 16) & 0xff] ^ crc_table[0][c >> 24]
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   259
#define DOLIT32 DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4; DOLIT4
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   260
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   261
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   262
local unsigned long crc32_little(crc, buf, len)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   263
    unsigned long crc;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   264
    const unsigned char FAR *buf;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   265
    unsigned len;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   266
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   267
    register u4 c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   268
    register const u4 FAR *buf4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   269
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   270
    c = (u4)crc;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   271
    c = ~c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   272
    while (len && ((ptrdiff_t)buf & 3)) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   273
        c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   274
        len--;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   275
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   276
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   277
    buf4 = (const u4 FAR *)(const void FAR *)buf;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   278
    while (len >= 32) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   279
        DOLIT32;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   280
        len -= 32;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   281
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   282
    while (len >= 4) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   283
        DOLIT4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   284
        len -= 4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   285
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   286
    buf = (const unsigned char FAR *)buf4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   287
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   288
    if (len) do {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   289
        c = crc_table[0][(c ^ *buf++) & 0xff] ^ (c >> 8);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   290
    } while (--len);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   291
    c = ~c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   292
    return (unsigned long)c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   293
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   294
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   295
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   296
#define DOBIG4 c ^= *++buf4; \
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   297
        c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   298
            crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24]
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   299
#define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   300
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   301
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   302
local unsigned long crc32_big(crc, buf, len)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   303
    unsigned long crc;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   304
    const unsigned char FAR *buf;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   305
    unsigned len;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   306
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   307
    register u4 c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   308
    register const u4 FAR *buf4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   309
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   310
    c = REV((u4)crc);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   311
    c = ~c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   312
    while (len && ((ptrdiff_t)buf & 3)) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   313
        c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   314
        len--;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   315
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   316
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   317
    buf4 = (const u4 FAR *)(const void FAR *)buf;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   318
    buf4--;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   319
    while (len >= 32) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   320
        DOBIG32;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   321
        len -= 32;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   322
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   323
    while (len >= 4) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   324
        DOBIG4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   325
        len -= 4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   326
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   327
    buf4++;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   328
    buf = (const unsigned char FAR *)buf4;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   329
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   330
    if (len) do {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   331
        c = crc_table[4][(c >> 24) ^ *buf++] ^ (c << 8);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   332
    } while (--len);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   333
    c = ~c;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   334
    return (unsigned long)(REV(c));
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   335
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   336
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   337
#endif /* BYFOUR */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   338
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   339
#define GF2_DIM 32      /* dimension of GF(2) vectors (length of CRC) */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   340
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   341
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   342
local unsigned long gf2_matrix_times(mat, vec)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   343
    unsigned long *mat;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   344
    unsigned long vec;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   345
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   346
    unsigned long sum;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   347
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   348
    sum = 0;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   349
    while (vec) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   350
        if (vec & 1)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   351
            sum ^= *mat;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   352
        vec >>= 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   353
        mat++;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   354
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   355
    return sum;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   356
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   357
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   358
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   359
local void gf2_matrix_square(square, mat)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   360
    unsigned long *square;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   361
    unsigned long *mat;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   362
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   363
    int n;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   364
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   365
    for (n = 0; n < GF2_DIM; n++)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   366
        square[n] = gf2_matrix_times(mat, mat[n]);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   367
}
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   368
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   369
/* ========================================================================= */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   370
uLong ZEXPORT crc32_combine(crc1, crc2, len2)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   371
    uLong crc1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   372
    uLong crc2;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   373
    z_off_t len2;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   374
{
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   375
    int n;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   376
    unsigned long row;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   377
    unsigned long even[GF2_DIM];    /* even-power-of-two zeros operator */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   378
    unsigned long odd[GF2_DIM];     /* odd-power-of-two zeros operator */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   379
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   380
    /* degenerate case */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   381
    if (len2 == 0)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   382
        return crc1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   383
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   384
    /* put operator for one zero bit in odd */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   385
    odd[0] = 0xedb88320L;           /* CRC-32 polynomial */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   386
    row = 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   387
    for (n = 1; n < GF2_DIM; n++) {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   388
        odd[n] = row;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   389
        row <<= 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   390
    }
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   391
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   392
    /* put operator for two zero bits in even */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   393
    gf2_matrix_square(even, odd);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   394
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   395
    /* put operator for four zero bits in odd */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   396
    gf2_matrix_square(odd, even);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   397
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   398
    /* apply len2 zeros to crc1 (first square will put the operator for one
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   399
       zero byte, eight zero bits, in even) */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   400
    do {
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   401
        /* apply zeros operator for this bit of len2 */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   402
        gf2_matrix_square(even, odd);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   403
        if (len2 & 1)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   404
            crc1 = gf2_matrix_times(even, crc1);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   405
        len2 >>= 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   406
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   407
        /* if no more bits set, then done */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   408
        if (len2 == 0)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   409
            break;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   410
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   411
        /* another iteration of the loop with odd and even swapped */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   412
        gf2_matrix_square(odd, even);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   413
        if (len2 & 1)
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   414
            crc1 = gf2_matrix_times(odd, crc1);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   415
        len2 >>= 1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   416
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   417
        /* if no more bits set, then done */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   418
    } while (len2 != 0);
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   419
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   420
    /* return combined crc */
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   421
    crc1 ^= crc2;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   422
    return crc1;
7b4677a8de6e Moved to zlib 1.2.3 proper.
Ryan C. Gordon <icculus@icculus.org>
parents:
diff changeset
   423
}