glossary-content.txt: rephrase magic signature part

diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index ae6ce0d95c9dee16975e43b37ed0b2b9e3ef61ea..62cb23dfd37743e4985655998ccabd56db160233 100644 (file)
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -143,6 +143,19 @@ long xdl_guess_lines(mmfile_t *mf, long sample) {
        return nl + 1;
 }
 
+int xdl_blankline(const char *line, long size, long flags)
+{
+       long i;
+
+       if (!(flags & XDF_WHITESPACE_FLAGS))
+               return (size <= 1);
+
+       for (i = 0; i < size && XDL_ISSPACE(line[i]); i++)
+               ;
+
+       return (i == size);
+}
+
 int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags)
 {
        int i1, i2;
@@ -251,9 +264,11 @@ static unsigned long xdl_hash_record_with_whitespace(char const **data,
 
 #ifdef XDL_FAST_HASH
 
-#define ONEBYTES       0x0101010101010101ul
-#define NEWLINEBYTES   0x0a0a0a0a0a0a0a0aul
-#define HIGHBITS       0x8080808080808080ul
+#define REPEAT_BYTE(x)  ((~0ul / 0xff) * (x))
+
+#define ONEBYTES       REPEAT_BYTE(0x01)
+#define NEWLINEBYTES   REPEAT_BYTE(0x0a)
+#define HIGHBITS       REPEAT_BYTE(0x80)
 
 /* Return the high bit set in the first byte that is a zero */
 static inline unsigned long has_zero(unsigned long a)
@@ -270,21 +285,19 @@ static inline long count_masked_bytes(unsigned long mask)
                 * that works for the bytemasks without having to
                 * mask them first.
                 */
-               return mask * 0x0001020304050608 >> 56;
-       } else {
                /*
-                * Modified Carl Chatfield G+ version for 32-bit *
+                * return mask * 0x0001020304050608 >> 56;
                 *
-                * (a) gives us
-                *   -1 (0, ff), 0 (ffff) or 1 (ffffff)
-                * (b) gives us
-                *   0 for 0, 1 for (ff ffff ffffff)
-                * (a+b+1) gives us
-                *   correct 0-3 bytemask count result
+                * Doing it like this avoids warnings on 32-bit machines.
                 */
-               long a = (mask - 256) >> 23;
-               long b = mask & 1;
-               return a + b + 1;
+               long a = (REPEAT_BYTE(0x01) / 0xff + 1);
+               return mask * a >> (sizeof(long) * 7);
+       } else {
+               /* Carl Chatfield / Jan Achrenius G+ version for 32-bit */
+               /* (000000 0000ff 00ffff ffffff) -> ( 1 1 2 3 ) */
+               long a = (0x0ff0001 + mask) >> 23;
+               /* Fix the 1 for 00 case */
+               return a & mask;
        }
 }