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* bignum.c (rb_big_pow): improvement by calculating from MSB and using

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factorization.  <http://yowaken.dip.jp/tdiary/20070426.html#p01>


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12236 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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nobu 2007-05-01 20:39:48 +00:00
parent 9ca1fec41b
commit 0c1f1fb531
3 changed files with 72 additions and 14 deletions
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5
ChangeLog
View file

@ -1,3 +1,8 @@
Wed May 2 05:40:43 2007 Nobuyoshi Nakada <nobu@ruby-lang.org>
* bignum.c (rb_big_pow): improvement by calculating from MSB and using
factorization. <http://yowaken.dip.jp/tdiary/20070426.html#p01>
Tue May 1 18:45:45 2007 Koichi Sasada <ko1@atdot.net>
* sample/test.rb: import matzruby's sample/test.rb.

73
bignum.c
View file

@ -1533,6 +1533,49 @@ rb_big_quo(VALUE x, VALUE y)
return rb_float_new(dx / dy);
}
static VALUE
bigsqr(VALUE x)
{
long len = RBIGNUM(x)->len, k = len / 2, i;
VALUE a, b, a2, z;
BDIGIT_DBL num;
if (len < 4000 / BITSPERDIG) {
return rb_big_mul0(x, x);
}
a = bignew(len - k, 1);
MEMCPY(BDIGITS(a), BDIGITS(x) + k, BDIGIT, len - k);
b = bignew(k, 1);
MEMCPY(BDIGITS(b), BDIGITS(x), BDIGIT, k);
a2 = bigtrunc(bigsqr(a));
z = bigsqr(b);
REALLOC_N(RBIGNUM(z)->digits, BDIGIT, (len = 2 * k + RBIGNUM(a2)->len) + 1);
while (RBIGNUM(z)->len < 2 * k) BDIGITS(z)[RBIGNUM(z)->len++] = 0;
MEMCPY(BDIGITS(z) + 2 * k, BDIGITS(a2), BDIGIT, RBIGNUM(a2)->len);
RBIGNUM(z)->len = len;
a2 = bigtrunc(rb_big_mul0(a, b));
len = RBIGNUM(a2)->len;
for (i = 0, num = 0; i < len; i++) {
num += (BDIGIT_DBL)BDIGITS(z)[i + k] + ((BDIGIT_DBL)BDIGITS(a2)[i] << 1);
BDIGITS(z)[i + k] = BIGLO(num);
num = BIGDN(num);
}
if (num) {
len = RBIGNUM(z)->len;
for (i += k; i < len && num; ++i) {
num += (BDIGIT_DBL)BDIGITS(z)[i];
BDIGITS(z)[i] = BIGLO(num);
num = BIGDN(num);
}
if (num) {
BDIGITS(z)[RBIGNUM(z)->len++] = BIGLO(num);
}
}
return bigtrunc(z);
}
/*
* call-seq:
* big ** exponent #=> numeric
@ -1550,7 +1593,7 @@ VALUE
rb_big_pow(VALUE x, VALUE y)
{
double d;
long yy;
SIGNED_VALUE yy;
if (y == INT2FIX(0)) return INT2FIX(1);
switch (TYPE(y)) {
@ -1566,21 +1609,31 @@ rb_big_pow(VALUE x, VALUE y)
case T_FIXNUM:
yy = FIX2LONG(y);
if (yy > 0) {
VALUE z = (yy & 1) ? x : 0;
VALUE z = 0;
SIGNED_VALUE mask, n = 1;
if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) {
rb_warn("in a**b, b may be too big");
d = (double)yy;
break;
}
while (yy &= ~1) {
do {
yy /= 2;
x = rb_big_mul0(x, x);
bigtrunc(x);
} while (yy % 2 == 0);
z = z ? rb_big_mul0(z, x) : x;
bigtrunc(z);
for (mask = FIXNUM_MAX + 1; mask; mask >>= 1) {
if (!z) {
SIGNED_VALUE n2 = n * n;
if (!POSFIXABLE(n2) || (n2 / n != n)) {
z = bigtrunc(bigsqr(rb_int2big(n)));
}
else {
n = n2;
}
}
else {
z = bigtrunc(bigsqr(z));
}
if (yy & mask) {
if (!z) z = rb_int2big(n);
z = bigtrunc(rb_big_mul0(z, x));
}
}
return bignorm(z);
}

6
version.h
View file

@ -1,7 +1,7 @@
#define RUBY_VERSION "1.9.0"
#define RUBY_RELEASE_DATE "2007-05-01"
#define RUBY_RELEASE_DATE "2007-05-02"
#define RUBY_VERSION_CODE 190
#define RUBY_RELEASE_CODE 20070501
#define RUBY_RELEASE_CODE 20070502
#define RUBY_PATCHLEVEL 0
#define RUBY_VERSION_MAJOR 1
@ -9,7 +9,7 @@
#define RUBY_VERSION_TEENY 0
#define RUBY_RELEASE_YEAR 2007
#define RUBY_RELEASE_MONTH 5
#define RUBY_RELEASE_DAY 1
#define RUBY_RELEASE_DAY 2
#ifdef RUBY_EXTERN
RUBY_EXTERN const char ruby_version[];