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authorcvs2git <rtems-devel@rtems.org>2011-03-18 10:11:42 +0000
committercvs2git <rtems-devel@rtems.org>2011-03-18 10:11:42 +0000
commite371ea9949ecc8897f4cb34437cc6590a0fc51f0 (patch)
treee5d17499fe12fc87c9697d681b63b062e9cbb65a /cpukit/zlib/adler32.c
parent83dcd23af45446b24fe12e5bce29432debe6d0b5 (diff)
This commit was manufactured by cvs2svn to create tag 'rtems-4-10-0'.4.10.0
Sprout from rtems-4-10-branch 2011-02-08 15:56:24 UTC Joel Sherrill <joel.sherrill@OARcorp.com> 'Ensure all version instances say 4.10.' Cherrypick from rtems-4-10-branch 2011-03-18 10:11:41 UTC cvs2git <rtems-devel@rtems.org> 'This commit was manufactured by cvs2svn to create branch': cpukit/zlib/ChangeLog cpukit/zlib/ChangeLog.zlib cpukit/zlib/FAQ cpukit/zlib/Makefile.am cpukit/zlib/README cpukit/zlib/adler32.c cpukit/zlib/compress.c cpukit/zlib/crc32.c cpukit/zlib/deflate.c cpukit/zlib/deflate.h cpukit/zlib/doc/algorithm.txt cpukit/zlib/gzclose.c cpukit/zlib/gzguts.h cpukit/zlib/gzlib.c cpukit/zlib/gzread.c cpukit/zlib/gzwrite.c cpukit/zlib/infback.c cpukit/zlib/inffast.c cpukit/zlib/inflate.c cpukit/zlib/inflate.h cpukit/zlib/inftrees.c cpukit/zlib/inftrees.h cpukit/zlib/trees.c cpukit/zlib/uncompr.c cpukit/zlib/zconf.h cpukit/zlib/zlib.3 cpukit/zlib/zlib.h cpukit/zlib/zutil.c cpukit/zlib/zutil.h testsuites/libtests/mathf/.cvsignore testsuites/libtests/mathf/Makefile.am testsuites/libtests/mathf/domathf.c testsuites/libtests/mathf/init.c testsuites/libtests/mathf/mathf.scn
Diffstat (limited to 'cpukit/zlib/adler32.c')
-rw-r--r--cpukit/zlib/adler32.c171
1 files changed, 171 insertions, 0 deletions
diff --git a/cpukit/zlib/adler32.c b/cpukit/zlib/adler32.c
new file mode 100644
index 0000000000..6889548657
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+++ b/cpukit/zlib/adler32.c
@@ -0,0 +1,171 @@
+/* adler32.c -- compute the Adler-32 checksum of a data stream
+ * Copyright (C) 1995-2007 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+/* @(#) $Id$ */
+
+#include "zutil.h"
+
+#define local static
+
+local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2);
+
+#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) {adler += (buf)[i]; sum2 += adler;}
+#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);
+
+/* use NO_DIVIDE if your processor does not do division in hardware */
+#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)
+# define MOD4(a) \
+ do { \
+ 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
+# define MOD4(a) a %= BASE
+#endif
+
+/* ========================================================================= */
+uLong ZEXPORT adler32(adler, buf, len)
+ uLong adler;
+ const Bytef *buf;
+ uInt len;
+{
+ unsigned long sum2;
+ unsigned n;
+
+ /* split Adler-32 into component sums */
+ sum2 = (adler >> 16) & 0xffff;
+ adler &= 0xffff;
+
+ /* in case user likes doing a byte at a time, keep it fast */
+ if (len == 1) {
+ adler += buf[0];
+ if (adler >= BASE)
+ adler -= BASE;
+ sum2 += adler;
+ if (sum2 >= BASE)
+ sum2 -= BASE;
+ return adler | (sum2 << 16);
+ }
+
+ /* initial Adler-32 value (deferred check for len == 1 speed) */
+ if (buf == Z_NULL)
+ return 1L;
+
+ /* in case short lengths are provided, keep it somewhat fast */
+ if (len < 16) {
+ while (len--) {
+ adler += *buf++;
+ sum2 += adler;
+ }
+ if (adler >= BASE)
+ adler -= BASE;
+ MOD4(sum2); /* only added so many BASE's */
+ return adler | (sum2 << 16);
+ }
+
+ /* do length NMAX blocks -- requires just one modulo operation */
+ while (len >= NMAX) {
+ len -= NMAX;
+ n = NMAX / 16; /* NMAX is divisible by 16 */
+ do {
+ DO16(buf); /* 16 sums unrolled */
+ buf += 16;
+ } while (--n);
+ MOD(adler);
+ MOD(sum2);
+ }
+
+ /* do remaining bytes (less than NMAX, still just one modulo) */
+ if (len) { /* avoid modulos if none remaining */
+ while (len >= 16) {
+ len -= 16;
+ DO16(buf);
+ buf += 16;
+ }
+ while (len--) {
+ adler += *buf++;
+ sum2 += adler;
+ }
+ MOD(adler);
+ MOD(sum2);
+ }
+
+ /* return recombined sums */
+ return adler | (sum2 << 16);
+}
+
+/* ========================================================================= */
+local uLong adler32_combine_(adler1, adler2, len2)
+ uLong adler1;
+ uLong adler2;
+ z_off64_t len2;
+{
+ unsigned long sum1;
+ unsigned long sum2;
+ unsigned rem;
+
+ /* the derivation of this formula is left as an exercise for the reader */
+ rem = (unsigned)(len2 % BASE);
+ sum1 = adler1 & 0xffff;
+ sum2 = rem * sum1;
+ MOD(sum2);
+ sum1 += (adler2 & 0xffff) + BASE - 1;
+ sum2 += ((adler1 >> 16) & 0xffff) + ((adler2 >> 16) & 0xffff) + BASE - rem;
+ if (sum1 >= BASE) sum1 -= BASE;
+ if (sum1 >= BASE) sum1 -= BASE;
+ if (sum2 >= (BASE << 1)) sum2 -= (BASE << 1);
+ if (sum2 >= BASE) sum2 -= BASE;
+ return sum1 | (sum2 << 16);
+}
+
+/* ========================================================================= */
+uLong ZEXPORT adler32_combine(adler1, adler2, len2)
+ uLong adler1;
+ uLong adler2;
+ z_off_t len2;
+{
+ return adler32_combine_(adler1, adler2, len2);
+}
+
+#if (defined(_LARGEFILE64_SOURCE)||(_FILE_OFFSET_BITS == 64))
+uLong ZEXPORT adler32_combine64(adler1, adler2, len2)
+ uLong adler1;
+ uLong adler2;
+ z_off64_t len2;
+{
+ return adler32_combine_(adler1, adler2, len2);
+}
+#endif /* (defined(_LARGEFILE64_SOURCE)||(_FILE_OFFSET_BITS == 64)) */