diff options
Diffstat (limited to 'crc32.c')
| -rw-r--r-- | crc32.c | 41 |
1 files changed, 29 insertions, 12 deletions
@@ -1,5 +1,5 @@ /* crc32.c -- compute the CRC-32 of a data stream - * Copyright (C) 1995-2006, 2010, 2011, 2012 Mark Adler + * Copyright (C) 1995-2006, 2010, 2011, 2012, 2016 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 @@ -30,17 +30,15 @@ #include "zutil.h" /* for STDC and FAR definitions */ -#define local static - /* Definitions for doing the crc four data bytes at a time. */ #if !defined(NOBYFOUR) && defined(Z_U4) # define BYFOUR #endif #ifdef BYFOUR local unsigned long crc32_little OF((unsigned long, - const unsigned char FAR *, unsigned)); + const unsigned char FAR *, z_size_t)); local unsigned long crc32_big OF((unsigned long, - const unsigned char FAR *, unsigned)); + const unsigned char FAR *, z_size_t)); # define TBLS 8 #else # define TBLS 1 @@ -201,10 +199,10 @@ const z_crc_t FAR * ZEXPORT get_crc_table() #define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1 /* ========================================================================= */ -unsigned long ZEXPORT crc32(crc, buf, len) +unsigned long ZEXPORT crc32_z(crc, buf, len) unsigned long crc; const unsigned char FAR *buf; - uInt len; + z_size_t len; { if (buf == Z_NULL) return 0UL; @@ -235,8 +233,29 @@ unsigned long ZEXPORT crc32(crc, buf, len) return crc ^ 0xffffffffUL; } +/* ========================================================================= */ +unsigned long ZEXPORT crc32(crc, buf, len) + unsigned long crc; + const unsigned char FAR *buf; + uInt len; +{ + return crc32_z(crc, buf, len); +} + #ifdef BYFOUR +/* + This BYFOUR code accesses the passed unsigned char * buffer with a 32-bit + integer pointer type. This violates the strict aliasing rule, where a + compiler can assume, for optimization purposes, that two pointers to + fundamentally different types won't ever point to the same memory. This can + manifest as a problem only if one of the pointers is written to. This code + only reads from those pointers. So long as this code remains isolated in + this compilation unit, there won't be a problem. For this reason, this code + should not be copied and pasted into a compilation unit in which other code + writes to the buffer that is passed to these routines. + */ + /* ========================================================================= */ #define DOLIT4 c ^= *buf4++; \ c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \ @@ -247,7 +266,7 @@ unsigned long ZEXPORT crc32(crc, buf, len) local unsigned long crc32_little(crc, buf, len) unsigned long crc; const unsigned char FAR *buf; - unsigned len; + z_size_t len; { register z_crc_t c; register const z_crc_t FAR *buf4; @@ -278,7 +297,7 @@ local unsigned long crc32_little(crc, buf, len) } /* ========================================================================= */ -#define DOBIG4 c ^= *++buf4; \ +#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 @@ -287,7 +306,7 @@ local unsigned long crc32_little(crc, buf, len) local unsigned long crc32_big(crc, buf, len) unsigned long crc; const unsigned char FAR *buf; - unsigned len; + z_size_t len; { register z_crc_t c; register const z_crc_t FAR *buf4; @@ -300,7 +319,6 @@ local unsigned long crc32_big(crc, buf, len) } buf4 = (const z_crc_t FAR *)(const void FAR *)buf; - buf4--; while (len >= 32) { DOBIG32; len -= 32; @@ -309,7 +327,6 @@ local unsigned long crc32_big(crc, buf, len) DOBIG4; len -= 4; } - buf4++; buf = (const unsigned char FAR *)buf4; if (len) do { |