| /* adler32.c -- compute the Adler-32 checksum of a data stream |
| * Copyright (C) 1995-2011, 2016 Mark Adler |
| * For conditions of distribution and use, see copyright notice in zlib.h |
| */ |
| |
| #include "zbuild.h" |
| #include "functable.h" |
| #include "adler32_p.h" |
| |
| #ifdef ZLIB_COMPAT |
| unsigned long Z_EXPORT PREFIX(adler32_z)(unsigned long adler, const unsigned char *buf, size_t len) { |
| return (unsigned long)functable.adler32((uint32_t)adler, buf, len); |
| } |
| #else |
| uint32_t Z_EXPORT PREFIX(adler32_z)(uint32_t adler, const unsigned char *buf, size_t len) { |
| return functable.adler32(adler, buf, len); |
| } |
| #endif |
| |
| /* ========================================================================= */ |
| #ifdef ZLIB_COMPAT |
| unsigned long Z_EXPORT PREFIX(adler32)(unsigned long adler, const unsigned char *buf, unsigned int len) { |
| return (unsigned long)functable.adler32((uint32_t)adler, buf, len); |
| } |
| #else |
| uint32_t Z_EXPORT PREFIX(adler32)(uint32_t adler, const unsigned char *buf, uint32_t len) { |
| return functable.adler32(adler, buf, len); |
| } |
| #endif |
| |
| /* ========================================================================= */ |
| static uint32_t adler32_combine_(uint32_t adler1, uint32_t adler2, z_off64_t len2) { |
| uint32_t sum1; |
| uint32_t sum2; |
| unsigned rem; |
| |
| /* for negative len, return invalid adler32 as a clue for debugging */ |
| if (len2 < 0) |
| return 0xffffffff; |
| |
| /* the derivation of this formula is left as an exercise for the reader */ |
| len2 %= BASE; /* assumes len2 >= 0 */ |
| rem = (unsigned)len2; |
| sum1 = adler1 & 0xffff; |
| sum2 = rem * sum1; |
| sum2 %= BASE; |
| sum1 += (adler2 & 0xffff) + BASE - 1; |
| sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem; |
| if (sum1 >= BASE) sum1 -= BASE; |
| if (sum1 >= BASE) sum1 -= BASE; |
| if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1); |
| if (sum2 >= BASE) sum2 -= BASE; |
| return sum1 | (sum2 << 16); |
| } |
| |
| /* ========================================================================= */ |
| #ifdef ZLIB_COMPAT |
| unsigned long Z_EXPORT PREFIX(adler32_combine)(unsigned long adler1, unsigned long adler2, z_off_t len2) { |
| return (unsigned long)adler32_combine_((uint32_t)adler1, (uint32_t)adler2, len2); |
| } |
| |
| unsigned long Z_EXPORT PREFIX4(adler32_combine)(unsigned long adler1, unsigned long adler2, z_off64_t len2) { |
| return (unsigned long)adler32_combine_((uint32_t)adler1, (uint32_t)adler2, len2); |
| } |
| #else |
| uint32_t Z_EXPORT PREFIX4(adler32_combine)(uint32_t adler1, uint32_t adler2, z_off64_t len2) { |
| return adler32_combine_(adler1, adler2, len2); |
| } |
| #endif |