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* bignum.c (rb_big_pow): reduce multiplying for even number.

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* numeric.c (int_pow): calculate power in Fixnum as possible.
  [ruby-dev:30726]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12223 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
nobu 2007-04-26 08:30:10 +00:00
parent f70f8173cd
commit 93bdc98f33
3 changed files with 45 additions and 8 deletions
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7
ChangeLog
View file

@ -1,3 +1,10 @@
Thu Apr 26 17:31:00 2007 Nobuyoshi Nakada <nobu@ruby-lang.org>
* bignum.c (rb_big_pow): reduce multiplying for even number.
* numeric.c (int_pow): calculate power in Fixnum as possible.
[ruby-dev:30726]
Thu Apr 26 17:18:51 2007 Nobuyoshi Nakada <nobu@ruby-lang.org> Thu Apr 26 17:18:51 2007 Nobuyoshi Nakada <nobu@ruby-lang.org>
* parse.y: fixes for ripper. * parse.y: fixes for ripper.

12
bignum.c
View file

@ -1552,22 +1552,20 @@ rb_big_pow(VALUE x, VALUE y)
case T_FIXNUM: case T_FIXNUM:
yy = FIX2LONG(y); yy = FIX2LONG(y);
if (yy > 0) { if (yy > 0) {
VALUE z = x; VALUE z = (yy & 1) ? x : 0;
if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) { if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) {
rb_warn("in a**b, b may be too big"); rb_warn("in a**b, b may be too big");
d = (double)yy; d = (double)yy;
break; break;
} }
for (;;) { while (yy &= ~1) {
yy -= 1; do {
if (yy == 0) break;
while (yy % 2 == 0) {
yy /= 2; yy /= 2;
x = rb_big_mul0(x, x); x = rb_big_mul0(x, x);
if (!BDIGITS(x)[RBIGNUM(x)->len-1]) RBIGNUM(x)->len--; if (!BDIGITS(x)[RBIGNUM(x)->len-1]) RBIGNUM(x)->len--;
} } while (yy % 2 == 0);
z = rb_big_mul0(z, x); z = z ? rb_big_mul0(z, x) : x;
if (!BDIGITS(z)[RBIGNUM(z)->len-1]) RBIGNUM(z)->len--; if (!BDIGITS(z)[RBIGNUM(z)->len-1]) RBIGNUM(z)->len--;
} }
return bignorm(z); return bignorm(z);

34
numeric.c
View file

@ -2259,6 +2259,38 @@ fix_divmod(VALUE x, VALUE y)
} }
} }
static VALUE
int_pow(long x, unsigned long y)
{
int neg = x < 0;
long z = 1;
if (neg) x = -x;
if (y & 1) z = x;
y &= ~1;
do {
while (y % 2 == 0) {
long x2 = x * x;
if (x2 < x || !POSFIXABLE(x2)) {
bignum:
return rb_big_mul(rb_big_pow(rb_int2big(x), LONG2NUM(y)),
rb_int2big(neg ? -z : z));
}
x = x2;
y >>= 1;
}
{
long xz = x * z;
if (xz < z || xz < x || !POSFIXABLE(xz)) {
goto bignum;
}
z = xz;
}
} while (--y);
if (neg) z = -z;
return LONG2NUM(z);
}
/* /*
* call-seq: * call-seq:
* fix ** other => Numeric * fix ** other => Numeric
@ -2282,7 +2314,7 @@ fix_pow(VALUE x, VALUE y)
if (b == 1) return x; if (b == 1) return x;
a = FIX2LONG(x); a = FIX2LONG(x);
if (b > 0) { if (b > 0) {
return rb_big_pow(rb_int2big(a), y); return int_pow(a, b);
} }
return rb_float_new(pow((double)a, (double)b)); return rb_float_new(pow((double)a, (double)b));
} }