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8#define ZLIB_INTERNAL
9#include "zlib.h"
10
11#define BASE 65521UL
12#define NMAX 5552
13
14
15#define DO1(buf,i) {adler += (buf)[i]; sum2 += adler;}
16#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
17#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
18#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
19#define DO16(buf) DO8(buf,0); DO8(buf,8);
20
21
22#ifdef NO_DIVIDE
23# define MOD(a) \
24 do { \
25 if (a >= (BASE << 16)) a -= (BASE << 16); \
26 if (a >= (BASE << 15)) a -= (BASE << 15); \
27 if (a >= (BASE << 14)) a -= (BASE << 14); \
28 if (a >= (BASE << 13)) a -= (BASE << 13); \
29 if (a >= (BASE << 12)) a -= (BASE << 12); \
30 if (a >= (BASE << 11)) a -= (BASE << 11); \
31 if (a >= (BASE << 10)) a -= (BASE << 10); \
32 if (a >= (BASE << 9)) a -= (BASE << 9); \
33 if (a >= (BASE << 8)) a -= (BASE << 8); \
34 if (a >= (BASE << 7)) a -= (BASE << 7); \
35 if (a >= (BASE << 6)) a -= (BASE << 6); \
36 if (a >= (BASE << 5)) a -= (BASE << 5); \
37 if (a >= (BASE << 4)) a -= (BASE << 4); \
38 if (a >= (BASE << 3)) a -= (BASE << 3); \
39 if (a >= (BASE << 2)) a -= (BASE << 2); \
40 if (a >= (BASE << 1)) a -= (BASE << 1); \
41 if (a >= BASE) a -= BASE; \
42 } while (0)
43# define MOD4(a) \
44 do { \
45 if (a >= (BASE << 4)) a -= (BASE << 4); \
46 if (a >= (BASE << 3)) a -= (BASE << 3); \
47 if (a >= (BASE << 2)) a -= (BASE << 2); \
48 if (a >= (BASE << 1)) a -= (BASE << 1); \
49 if (a >= BASE) a -= BASE; \
50 } while (0)
51#else
52# define MOD(a) a %= BASE
53# define MOD4(a) a %= BASE
54#endif
55
56
57uLong ZEXPORT adler32(uLong adler, const Bytef *buf, uInt len)
58{
59 unsigned long sum2;
60 unsigned n;
61
62
63 sum2 = (adler >> 16) & 0xffff;
64 adler &= 0xffff;
65
66
67 if (len == 1) {
68 adler += buf[0];
69 if (adler >= BASE)
70 adler -= BASE;
71 sum2 += adler;
72 if (sum2 >= BASE)
73 sum2 -= BASE;
74 return adler | (sum2 << 16);
75 }
76
77
78 if (buf == Z_NULL)
79 return 1L;
80
81
82 if (len < 16) {
83 while (len--) {
84 adler += *buf++;
85 sum2 += adler;
86 }
87 if (adler >= BASE)
88 adler -= BASE;
89 MOD4(sum2);
90 return adler | (sum2 << 16);
91 }
92
93
94 while (len >= NMAX) {
95 len -= NMAX;
96 n = NMAX / 16;
97 do {
98 DO16(buf);
99 buf += 16;
100 } while (--n);
101 MOD(adler);
102 MOD(sum2);
103 }
104
105
106 if (len) {
107 while (len >= 16) {
108 len -= 16;
109 DO16(buf);
110 buf += 16;
111 }
112 while (len--) {
113 adler += *buf++;
114 sum2 += adler;
115 }
116 MOD(adler);
117 MOD(sum2);
118 }
119
120
121 return adler | (sum2 << 16);
122}
123