FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavutil/adler32.c
Date: 2024-02-16 17:37:06
Exec Total Coverage
Lines: 29 29 100.0%
Functions: 1 1 100.0%
Branches: 6 6 100.0%

Line Branch Exec Source
1 /*
2 * Compute the Adler-32 checksum of a data stream.
3 * This is a modified version based on adler32.c from the zlib library.
4 *
5 * Copyright (C) 1995 Mark Adler
6 *
7 * This software is provided 'as-is', without any express or implied
8 * warranty. In no event will the authors be held liable for any damages
9 * arising from the use of this software.
10 *
11 * Permission is granted to anyone to use this software for any purpose,
12 * including commercial applications, and to alter it and redistribute it
13 * freely, subject to the following restrictions:
14 *
15 * 1. The origin of this software must not be misrepresented; you must not
16 * claim that you wrote the original software. If you use this software
17 * in a product, an acknowledgment in the product documentation would be
18 * appreciated but is not required.
19 * 2. Altered source versions must be plainly marked as such, and must not be
20 * misrepresented as being the original software.
21 * 3. This notice may not be removed or altered from any source distribution.
22 */
23
24 /**
25 * @file
26 * Computes the Adler-32 checksum of a data stream
27 *
28 * This is a modified version based on adler32.c from the zlib library.
29 * @author Mark Adler
30 * @ingroup lavu_adler32
31 */
32
33 #include "config.h"
34 #include "adler32.h"
35 #include "intreadwrite.h"
36 #include "macros.h"
37
38 #define BASE 65521L /* largest prime smaller than 65536 */
39
40 #define DO1(buf) { s1 += *buf++; s2 += s1; }
41 #define DO4(buf) DO1(buf); DO1(buf); DO1(buf); DO1(buf);
42 #define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
43
44 100072 AVAdler av_adler32_update(AVAdler adler, const uint8_t *buf, size_t len)
45 {
46 100072 unsigned long s1 = adler & 0xffff;
47 100072 unsigned long s2 = adler >> 16;
48
49
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137826664 while (len > 0) {
50 #if HAVE_FAST_64BIT && HAVE_FAST_UNALIGNED && !CONFIG_SMALL
51 137726592 unsigned len2 = FFMIN((len-1) & ~7, 23*8);
52
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137726592 if (len2) {
53 137399826 uint64_t a1= 0;
54 137399826 uint64_t a2= 0;
55 137399826 uint64_t b1= 0;
56 137399826 uint64_t b2= 0;
57 137399826 len -= len2;
58 137399826 s2 += s1*len2;
59
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3296466960 while (len2 >= 8) {
60 3159067134 uint64_t v = AV_RN64(buf);
61 3159067134 a2 += a1;
62 3159067134 b2 += b1;
63 3159067134 a1 += v &0x00FF00FF00FF00FF;
64 3159067134 b1 += (v>>8)&0x00FF00FF00FF00FF;
65 3159067134 len2 -= 8;
66 3159067134 buf+=8;
67 }
68
69 //We combine the 8 interleaved adler32 checksums without overflows
70 //Decreasing the number of iterations would allow below code to be
71 //simplified but would likely be slower due to the fewer iterations
72 //of the inner loop
73 137399826 s1 += ((a1+b1)*0x1000100010001)>>48;
74 137399826 s2 += ((((a2&0xFFFF0000FFFF)+(b2&0xFFFF0000FFFF)+((a2>>16)&0xFFFF0000FFFF)+((b2>>16)&0xFFFF0000FFFF))*0x800000008)>>32)
75 #if HAVE_BIGENDIAN
76 + 2*((b1*0x1000200030004)>>48)
77 + ((a1*0x1000100010001)>>48)
78 + 2*((a1*0x0000100020003)>>48);
79 #else
80 137399826 + 2*((a1*0x4000300020001)>>48)
81 137399826 + ((b1*0x1000100010001)>>48)
82 137399826 + 2*((b1*0x3000200010000)>>48);
83 #endif
84 }
85 #else
86 while (len > 4 && s2 < (1U << 31)) {
87 DO4(buf);
88 len -= 4;
89 }
90 #endif
91 137726592 DO1(buf); len--;
92 137726592 s1 %= BASE;
93 137726592 s2 %= BASE;
94 }
95 100072 return (s2 << 16) | s1;
96 }
97