- register const unsigned char *haystack, *needle;
- register chartype b, c;
-
- haystack = (const unsigned char *) phaystack;
- needle = (const unsigned char *) pneedle;
-
- b = *needle;
- if (b != '\0')
- {
- haystack--; /* possible ANSI violation */
- do
- {
- c = *++haystack;
- if (c == '\0')
- goto ret0;
- }
- while (c != b);
-
- c = *++needle;
- if (c == '\0')
- goto foundneedle;
- ++needle;
- goto jin;
-
- for (;;)
- {
- register chartype a;
- register const unsigned char *rhaystack, *rneedle;
-
- do
- {
- a = *++haystack;
- if (a == '\0')
- goto ret0;
- if (a == b)
- break;
- a = *++haystack;
- if (a == '\0')
- goto ret0;
-shloop:; }
- while (a != b);
-
-jin: a = *++haystack;
- if (a == '\0')
- goto ret0;
-
- if (a != c)
- goto shloop;
-
- rhaystack = haystack-- + 1;
- rneedle = needle;
- a = *rneedle;
-
- if (*rhaystack == a)
- do
- {
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = *++needle;
- if (*rhaystack != a)
- break;
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = *++needle;
- }
- while (*rhaystack == a);
-
- needle = rneedle; /* took the register-poor approach */
-
- if (a == '\0')
- break;
- }
- }
-foundneedle:
- return (char*) haystack;
-ret0:
- return 0;
+ const char *haystack = haystack_start;
+ const char *needle = needle_start;
+ size_t needle_len; /* Length of NEEDLE. */
+ size_t haystack_len; /* Known minimum length of HAYSTACK. */
+ bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
+
+ /* Determine length of NEEDLE, and in the process, make sure
+ HAYSTACK is at least as long (no point processing all of a long
+ NEEDLE if HAYSTACK is too short). */
+ while (*haystack && *needle)
+ ok &= *haystack++ == *needle++;
+ if (*needle)
+ return NULL;
+ if (ok)
+ return (char *) haystack_start;
+
+ /* Reduce the size of haystack using strchr, since it has a smaller
+ linear coefficient than the Two-Way algorithm. */
+ needle_len = needle - needle_start;
+ haystack = strchr (haystack_start + 1, *needle_start);
+ if (!haystack || __builtin_expect (needle_len == 1, 0))
+ return (char *) haystack;
+ needle -= needle_len;
+ haystack_len = (haystack > haystack_start + needle_len ? 1
+ : needle_len + haystack_start - haystack);
+
+ /* Perform the search. Abstract memory is considered to be an array
+ of 'unsigned char' values, not an array of 'char' values. See
+ ISO C 99 section 6.2.6.1. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ return two_way_short_needle ((const unsigned char *) haystack,
+ haystack_len,
+ (const unsigned char *) needle, needle_len);
+ return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+ (const unsigned char *) needle, needle_len);