Add comments explaining the workaround for mingw 3.2.3

[wxWidgets.git] / src / zlib / adler32.c

diff --git a/src/zlib/adler32.c b/src/zlib/adler32.c
index ef4b2ebdc88bbb207b6b1e55e34333af3f22b606..624a1696eb03533349208d6fdbf5935be086b352 100644 (file)
--- a/src/zlib/adler32.c
+++ b/src/zlib/adler32.c
@@ -1,13 +1,14 @@
 /* adler32.c -- compute the Adler-32 checksum of a data stream
 /* adler32.c -- compute the Adler-32 checksum of a data stream

- * Copyright (C) 1995-1998 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h 
+ * Copyright (C) 1995-2003 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h

  */
 
 /* @(#) $Id$ */
 
  */
 
 /* @(#) $Id$ */
 

-#include "../zlib/zlib.h"
+#define ZLIB_INTERNAL
+#include "zlib.h"

 
 

-#define BASE 65521L /* largest prime smaller than 65536 */
+#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 NMAX 5552
 /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
 


@@ -17,6 +18,31 @@
 #define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
 #define DO16(buf)   DO8(buf,0); DO8(buf,8);
 
 #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;
 /* ========================================================================= */
 uLong ZEXPORT adler32(adler, buf, len)
     uLong adler;


@@ -30,19 +56,19 @@ uLong ZEXPORT adler32(adler, buf, len)
     if (buf == Z_NULL) return 1L;
 
     while (len > 0) {
     if (buf == Z_NULL) return 1L;
 
     while (len > 0) {

-        k = len < NMAX ? len : NMAX;
+        k = len < NMAX ? (int)len : NMAX;

         len -= k;
         while (k >= 16) {
             DO16(buf);
         len -= k;
         while (k >= 16) {
             DO16(buf);

-           buf += 16;
+            buf += 16;

             k -= 16;
         }
         if (k != 0) do {
             s1 += *buf++;
             k -= 16;
         }
         if (k != 0) do {
             s1 += *buf++;

-           s2 += s1;
+            s2 += s1;

         } while (--k);
         } while (--k);

-        s1 %= BASE;
-        s2 %= BASE;
+        MOD(s1);
+        MOD(s2);

     }
     return (s2 << 16) | s1;
 }
     }
     return (s2 << 16) | s1;
 }