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* random.c (limited_rand): Add a specialized path for the limit fits in 32 bit.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53914 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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akr 2016-02-24 12:30:20 +00:00
parent d4819da611
commit 169b867fbf
2 changed files with 24 additions and 9 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
Wed Feb 24 21:03:04 2016 Tanaka Akira <akr@fsij.org>
* random.c (limited_rand): Add a specialized path for the limit fits
in 32 bit.
Tue Feb 23 21:52:24 2016 Martin Duerst <duerst@it.aoyama.ac.jp> Tue Feb 23 21:52:24 2016 Martin Duerst <duerst@it.aoyama.ac.jp>
* enc/unicode/case-folding.rb, casefold.h: Outputting actual titlecase * enc/unicode/case-folding.rb, casefold.h: Outputting actual titlecase

28
random.c
View File

@ -826,21 +826,31 @@ static unsigned long
limited_rand(struct MT *mt, unsigned long limit) limited_rand(struct MT *mt, unsigned long limit)
{ {
/* mt must be initialized */ /* mt must be initialized */
int i;
unsigned long val, mask; unsigned long val, mask;
if (!limit) return 0; if (!limit) return 0;
mask = make_mask(limit); mask = make_mask(limit);
retry:
val = 0; #if 4 < SIZEOF_LONG
for (i = SIZEOF_LONG/SIZEOF_INT32-1; 0 <= i; i--) { if (0xffffffff < limit) {
if ((mask >> (i * 32)) & 0xffffffff) { int i;
val |= (unsigned long)genrand_int32(mt) << (i * 32); retry:
val &= mask; val = 0;
if (limit < val) for (i = SIZEOF_LONG/SIZEOF_INT32-1; 0 <= i; i--) {
goto retry; if ((mask >> (i * 32)) & 0xffffffff) {
val |= (unsigned long)genrand_int32(mt) << (i * 32);
val &= mask;
if (limit < val)
goto retry;
}
} }
return val;
} }
#endif
do {
val = genrand_int32(mt) & mask;
} while (limit < val);
return val; return val;
} }