Line | Count | Source |
1 | | /* adler32.c -- compute the Adler-32 checksum of a data stream |
2 | | * Copyright (C) 1995-2011, 2016 Mark Adler |
3 | | * For conditions of distribution and use, see copyright notice in zlib.h |
4 | | */ |
5 | | |
6 | | #include "zbuild.h" |
7 | | #include "functable.h" |
8 | | #include "adler32_p.h" |
9 | | |
10 | | #ifdef ZLIB_COMPAT |
11 | | unsigned long Z_EXPORT PREFIX(adler32_z)(unsigned long adler, const unsigned char *buf, size_t len) { |
12 | | if (buf == NULL) |
13 | | return ADLER32_INITIAL_VALUE; |
14 | | return (unsigned long)FUNCTABLE_CALL(adler32)((uint32_t)adler, buf, len); |
15 | | } |
16 | | #else |
17 | 2.12M | uint32_t Z_EXPORT PREFIX(adler32_z)(uint32_t adler, const unsigned char *buf, size_t len) { |
18 | 2.12M | if (buf == NULL) |
19 | 0 | return ADLER32_INITIAL_VALUE; |
20 | 2.12M | return FUNCTABLE_CALL(adler32)(adler, buf, len); |
21 | 2.12M | } |
22 | | #endif |
23 | | |
24 | | /* ========================================================================= */ |
25 | | #ifdef ZLIB_COMPAT |
26 | | unsigned long Z_EXPORT PREFIX(adler32)(unsigned long adler, const unsigned char *buf, unsigned int len) { |
27 | | if (buf == NULL) |
28 | | return ADLER32_INITIAL_VALUE; |
29 | | return (unsigned long)FUNCTABLE_CALL(adler32)((uint32_t)adler, buf, len); |
30 | | } |
31 | | #else |
32 | 624 | uint32_t Z_EXPORT PREFIX(adler32)(uint32_t adler, const unsigned char *buf, uint32_t len) { |
33 | 624 | if (buf == NULL) |
34 | 624 | return ADLER32_INITIAL_VALUE; |
35 | 0 | return FUNCTABLE_CALL(adler32)(adler, buf, len); |
36 | 624 | } |
37 | | #endif |
38 | | |
39 | | /* ========================================================================= */ |
40 | 1.24k | static uint32_t adler32_combine_(uint32_t adler1, uint32_t adler2, z_off64_t len2) { |
41 | 1.24k | uint32_t sum1; |
42 | 1.24k | uint32_t sum2; |
43 | 1.24k | unsigned rem; |
44 | | |
45 | | /* for negative len, return invalid adler32 as a clue for debugging */ |
46 | 1.24k | if (len2 < 0) |
47 | 0 | return 0xffffffff; |
48 | | |
49 | | /* the derivation of this formula is left as an exercise for the reader */ |
50 | 1.24k | len2 %= BASE; /* assumes len2 >= 0 */ |
51 | 1.24k | rem = (unsigned)len2; |
52 | 1.24k | sum1 = adler1 & 0xffff; |
53 | 1.24k | sum2 = rem * sum1; |
54 | 1.24k | sum2 %= BASE; |
55 | 1.24k | sum1 += (adler2 & 0xffff) + BASE - 1; |
56 | 1.24k | sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem; |
57 | 1.24k | if (sum1 >= BASE) sum1 -= BASE; |
58 | 1.24k | if (sum1 >= BASE) sum1 -= BASE; |
59 | 1.24k | if (sum2 >= ((unsigned long)BASE << 1)) sum2 -= ((unsigned long)BASE << 1); |
60 | 1.24k | if (sum2 >= BASE) sum2 -= BASE; |
61 | 1.24k | return sum1 | (sum2 << 16); |
62 | 1.24k | } |
63 | | |
64 | | /* ========================================================================= */ |
65 | | #ifdef ZLIB_COMPAT |
66 | | unsigned long Z_EXPORT PREFIX(adler32_combine)(unsigned long adler1, unsigned long adler2, z_off_t len2) { |
67 | | return (unsigned long)adler32_combine_((uint32_t)adler1, (uint32_t)adler2, len2); |
68 | | } |
69 | | |
70 | | unsigned long Z_EXPORT PREFIX4(adler32_combine)(unsigned long adler1, unsigned long adler2, z_off64_t len2) { |
71 | | return (unsigned long)adler32_combine_((uint32_t)adler1, (uint32_t)adler2, len2); |
72 | | } |
73 | | #else |
74 | 1.24k | uint32_t Z_EXPORT PREFIX4(adler32_combine)(uint32_t adler1, uint32_t adler2, z_off64_t len2) { |
75 | 1.24k | return adler32_combine_(adler1, adler2, len2); |
76 | 1.24k | } |
77 | | #endif |