mirror of
https://git.ffmpeg.org/ffmpeg.git
synced 2024-12-30 19:32:13 +00:00
96d616052b
* commit 'd12b5b2f135aade4099f4b26b0fe678656158c13': build: Split test programs off into separate files Some conversions done by: James Almer <jamrial@gmail.com> Merged-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
98 lines
3.3 KiB
C
98 lines
3.3 KiB
C
/*
|
|
* Compute the Adler-32 checksum of a data stream.
|
|
* This is a modified version based on adler32.c from the zlib library.
|
|
*
|
|
* Copyright (C) 1995 Mark Adler
|
|
*
|
|
* This software is provided 'as-is', without any express or implied
|
|
* warranty. In no event will the authors be held liable for any damages
|
|
* arising from the use of this software.
|
|
*
|
|
* Permission is granted to anyone to use this software for any purpose,
|
|
* including commercial applications, and to alter it and redistribute it
|
|
* freely, subject to the following restrictions:
|
|
*
|
|
* 1. The origin of this software must not be misrepresented; you must not
|
|
* claim that you wrote the original software. If you use this software
|
|
* in a product, an acknowledgment in the product documentation would be
|
|
* appreciated but is not required.
|
|
* 2. Altered source versions must be plainly marked as such, and must not be
|
|
* misrepresented as being the original software.
|
|
* 3. This notice may not be removed or altered from any source distribution.
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* Computes the Adler-32 checksum of a data stream
|
|
*
|
|
* This is a modified version based on adler32.c from the zlib library.
|
|
* @author Mark Adler
|
|
* @ingroup lavu_adler32
|
|
*/
|
|
|
|
#include "config.h"
|
|
#include "adler32.h"
|
|
#include "common.h"
|
|
#include "intreadwrite.h"
|
|
|
|
#define BASE 65521L /* largest prime smaller than 65536 */
|
|
|
|
#define DO1(buf) { s1 += *buf++; s2 += s1; }
|
|
#define DO4(buf) DO1(buf); DO1(buf); DO1(buf); DO1(buf);
|
|
#define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
|
|
|
|
unsigned long av_adler32_update(unsigned long adler, const uint8_t * buf,
|
|
unsigned int len)
|
|
{
|
|
unsigned long s1 = adler & 0xffff;
|
|
unsigned long s2 = adler >> 16;
|
|
|
|
while (len > 0) {
|
|
#if HAVE_FAST_64BIT && HAVE_FAST_UNALIGNED && !CONFIG_SMALL
|
|
unsigned len2 = FFMIN((len-1) & ~7, 23*8);
|
|
if (len2) {
|
|
uint64_t a1= 0;
|
|
uint64_t a2= 0;
|
|
uint64_t b1= 0;
|
|
uint64_t b2= 0;
|
|
len -= len2;
|
|
s2 += s1*len2;
|
|
while (len2 >= 8) {
|
|
uint64_t v = AV_RN64(buf);
|
|
a2 += a1;
|
|
b2 += b1;
|
|
a1 += v &0x00FF00FF00FF00FF;
|
|
b1 += (v>>8)&0x00FF00FF00FF00FF;
|
|
len2 -= 8;
|
|
buf+=8;
|
|
}
|
|
|
|
//We combine the 8 interleaved adler32 checksums without overflows
|
|
//Decreasing the number of iterations would allow below code to be
|
|
//simplified but would likely be slower due to the fewer iterations
|
|
//of the inner loop
|
|
s1 += ((a1+b1)*0x1000100010001)>>48;
|
|
s2 += ((((a2&0xFFFF0000FFFF)+(b2&0xFFFF0000FFFF)+((a2>>16)&0xFFFF0000FFFF)+((b2>>16)&0xFFFF0000FFFF))*0x800000008)>>32)
|
|
#if HAVE_BIGENDIAN
|
|
+ 2*((b1*0x1000200030004)>>48)
|
|
+ ((a1*0x1000100010001)>>48)
|
|
+ 2*((a1*0x0000100020003)>>48);
|
|
#else
|
|
+ 2*((a1*0x4000300020001)>>48)
|
|
+ ((b1*0x1000100010001)>>48)
|
|
+ 2*((b1*0x3000200010000)>>48);
|
|
#endif
|
|
}
|
|
#else
|
|
while (len > 4 && s2 < (1U << 31)) {
|
|
DO4(buf);
|
|
len -= 4;
|
|
}
|
|
#endif
|
|
DO1(buf); len--;
|
|
s1 %= BASE;
|
|
s2 %= BASE;
|
|
}
|
|
return (s2 << 16) | s1;
|
|
}
|