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authornobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2003-02-03 07:34:06 +0000
committernobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2003-02-03 07:34:06 +0000
commit056585d6dc58c4b9b1e4bf5e58c0bc81b5122fc6 (patch)
tree3ac75a89db960d7cfd4a3614da06a96f100bf824 /re.c
parentddce7d5ebf870f437abe10bcc67ce6dbe6c4980b (diff)
* re.c (rb_memsearch): a little improvement.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3434 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 're.c')
-rw-r--r--re.c25
1 files changed, 13 insertions, 12 deletions
diff --git a/re.c b/re.c
index 8828119..dbf9bdf 100644
--- a/re.c
+++ b/re.c
@@ -103,46 +103,47 @@ rb_memsearch(x0, m, y0, n)
{
unsigned char *x = x0, *y = y0;
unsigned char *s, *e;
- long d, i;
+ long i;
+ int d;
unsigned long hx, hy;
-#define KR_REHASH(a, b, h) ((((h) - (a)*d) << 1) + (b))
+#define KR_REHASH(a, b, h) (((h) << 1) - ((a)<<d) + (b))
s = y; e = s + n - m + 1;
/* Preprocessing */
/* computes d = 2^(m-1) with
the left-shift operator */
- for (d = i = 1; i < m; ++i)
- d = (d<<1);
+ d = sizeof(hx) * CHAR_BIT - 1;
+ if (d > m) d = m;
if (ruby_ignorecase) {
/* Prepare hash value */
- for (hy = hx = i = 0; i < m; ++i) {
- hx = ((hx<<1) + casetable[x[i]]);
- hy = ((hy<<1) + casetable[s[i]]);
+ for (hy = hx = i = 0; i < d; ++i) {
+ hx = KR_REHASH(0, casetable[x[i]], hx);
+ hy = KR_REHASH(0, casetable[s[i]], hy);
}
/* Searching */
while (s < e) {
if (hx == hy && rb_memcicmp(x, s, m) == 0) {
return s-y;
}
- hy = KR_REHASH(casetable[*s], casetable[*(s+m)], hy);
+ hy = KR_REHASH(casetable[*s], casetable[*(s+d)], hy);
s++;
}
}
else {
/* Prepare hash value */
- for (hy = hx = i = 0; i < m; ++i) {
- hx = ((hx<<1) + x[i]);
- hy = ((hy<<1) + s[i]);
+ for (hy = hx = i = 0; i < d; ++i) {
+ hx = KR_REHASH(0, x[i], hx);
+ hy = KR_REHASH(0, s[i], hy);
}
/* Searching */
while (s < e) {
if (hx == hy && memcmp(x, s, m) == 0) {
return s-y;
}
- hy = KR_REHASH(*s, *(s+m), hy);
+ hy = KR_REHASH(*s, *(s+d), hy);
s++;
}
}