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-rw-r--r--com32/lib/zlib/adler32.c74
1 files changed, 74 insertions, 0 deletions
diff --git a/com32/lib/zlib/adler32.c b/com32/lib/zlib/adler32.c
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+++ b/com32/lib/zlib/adler32.c
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+/* adler32.c -- compute the Adler-32 checksum of a data stream
+ * Copyright (C) 1995-2003 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+/* @(#) $Id$ */
+
+#define ZLIB_INTERNAL
+#include "zlib.h"
+
+#define BASE 65521UL /* largest prime smaller than 65536 */
+#define NMAX 5552
+/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
+
+#define DO1(buf,i) {s1 += buf[i]; s2 += s1;}
+#define DO2(buf,i) DO1(buf,i); DO1(buf,i+1);
+#define DO4(buf,i) DO2(buf,i); DO2(buf,i+2);
+#define DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
+#define DO16(buf) DO8(buf,0); DO8(buf,8);
+
+#ifdef NO_DIVIDE
+# define MOD(a) \
+ do { \
+ if (a >= (BASE << 16)) a -= (BASE << 16); \
+ if (a >= (BASE << 15)) a -= (BASE << 15); \
+ if (a >= (BASE << 14)) a -= (BASE << 14); \
+ if (a >= (BASE << 13)) a -= (BASE << 13); \
+ if (a >= (BASE << 12)) a -= (BASE << 12); \
+ if (a >= (BASE << 11)) a -= (BASE << 11); \
+ if (a >= (BASE << 10)) a -= (BASE << 10); \
+ if (a >= (BASE << 9)) a -= (BASE << 9); \
+ if (a >= (BASE << 8)) a -= (BASE << 8); \
+ if (a >= (BASE << 7)) a -= (BASE << 7); \
+ if (a >= (BASE << 6)) a -= (BASE << 6); \
+ if (a >= (BASE << 5)) a -= (BASE << 5); \
+ if (a >= (BASE << 4)) a -= (BASE << 4); \
+ if (a >= (BASE << 3)) a -= (BASE << 3); \
+ if (a >= (BASE << 2)) a -= (BASE << 2); \
+ if (a >= (BASE << 1)) a -= (BASE << 1); \
+ if (a >= BASE) a -= BASE; \
+ } while (0)
+#else
+# define MOD(a) a %= BASE
+#endif
+
+/* ========================================================================= */
+uLong ZEXPORT adler32(adler, buf, len)
+ uLong adler;
+ const Bytef *buf;
+ uInt len;
+{
+ unsigned long s1 = adler & 0xffff;
+ unsigned long s2 = (adler >> 16) & 0xffff;
+ int k;
+
+ if (buf == Z_NULL) return 1L;
+
+ while (len > 0) {
+ k = len < NMAX ? (int)len : NMAX;
+ len -= k;
+ while (k >= 16) {
+ DO16(buf);
+ buf += 16;
+ k -= 16;
+ }
+ if (k != 0) do {
+ s1 += *buf++;
+ s2 += s1;
+ } while (--k);
+ MOD(s1);
+ MOD(s2);
+ }
+ return (s2 << 16) | s1;
+}