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/* 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_CALL(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_CALL(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_CALL(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_CALL(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
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