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* bignum.c (rb_big_pow): improvement by calculating from MSB and using
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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3 changed files with 72 additions and 14 deletions
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@ -1,3 +1,8 @@
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Wed May 2 05:40:43 2007 Nobuyoshi Nakada <nobu@ruby-lang.org>
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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>
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Tue May 1 18:45:45 2007 Koichi Sasada <ko1@atdot.net>
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* sample/test.rb: import matzruby's sample/test.rb.
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75
bignum.c
75
bignum.c
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@ -1533,6 +1533,49 @@ rb_big_quo(VALUE x, VALUE y)
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return rb_float_new(dx / dy);
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}
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static VALUE
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bigsqr(VALUE x)
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{
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long len = RBIGNUM(x)->len, k = len / 2, i;
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VALUE a, b, a2, z;
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BDIGIT_DBL num;
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if (len < 4000 / BITSPERDIG) {
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return rb_big_mul0(x, x);
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}
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a = bignew(len - k, 1);
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MEMCPY(BDIGITS(a), BDIGITS(x) + k, BDIGIT, len - k);
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b = bignew(k, 1);
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MEMCPY(BDIGITS(b), BDIGITS(x), BDIGIT, k);
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a2 = bigtrunc(bigsqr(a));
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z = bigsqr(b);
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REALLOC_N(RBIGNUM(z)->digits, BDIGIT, (len = 2 * k + RBIGNUM(a2)->len) + 1);
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while (RBIGNUM(z)->len < 2 * k) BDIGITS(z)[RBIGNUM(z)->len++] = 0;
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MEMCPY(BDIGITS(z) + 2 * k, BDIGITS(a2), BDIGIT, RBIGNUM(a2)->len);
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RBIGNUM(z)->len = len;
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a2 = bigtrunc(rb_big_mul0(a, b));
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len = RBIGNUM(a2)->len;
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for (i = 0, num = 0; i < len; i++) {
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num += (BDIGIT_DBL)BDIGITS(z)[i + k] + ((BDIGIT_DBL)BDIGITS(a2)[i] << 1);
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BDIGITS(z)[i + k] = BIGLO(num);
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num = BIGDN(num);
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}
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if (num) {
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len = RBIGNUM(z)->len;
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for (i += k; i < len && num; ++i) {
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num += (BDIGIT_DBL)BDIGITS(z)[i];
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BDIGITS(z)[i] = BIGLO(num);
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num = BIGDN(num);
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}
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if (num) {
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BDIGITS(z)[RBIGNUM(z)->len++] = BIGLO(num);
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}
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}
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return bigtrunc(z);
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}
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/*
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* call-seq:
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* big ** exponent #=> numeric
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@ -1550,8 +1593,8 @@ VALUE
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rb_big_pow(VALUE x, VALUE y)
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{
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double d;
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long yy;
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SIGNED_VALUE yy;
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if (y == INT2FIX(0)) return INT2FIX(1);
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switch (TYPE(y)) {
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case T_FLOAT:
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@ -1566,21 +1609,31 @@ rb_big_pow(VALUE x, VALUE y)
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case T_FIXNUM:
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yy = FIX2LONG(y);
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if (yy > 0) {
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VALUE z = (yy & 1) ? x : 0;
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VALUE z = 0;
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SIGNED_VALUE mask, n = 1;
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if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) {
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rb_warn("in a**b, b may be too big");
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d = (double)yy;
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break;
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}
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while (yy &= ~1) {
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do {
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yy /= 2;
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x = rb_big_mul0(x, x);
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bigtrunc(x);
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} while (yy % 2 == 0);
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z = z ? rb_big_mul0(z, x) : x;
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bigtrunc(z);
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for (mask = FIXNUM_MAX + 1; mask; mask >>= 1) {
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if (!z) {
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SIGNED_VALUE n2 = n * n;
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if (!POSFIXABLE(n2) || (n2 / n != n)) {
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z = bigtrunc(bigsqr(rb_int2big(n)));
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}
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else {
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n = n2;
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}
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}
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else {
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z = bigtrunc(bigsqr(z));
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}
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if (yy & mask) {
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if (!z) z = rb_int2big(n);
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z = bigtrunc(rb_big_mul0(z, x));
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}
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}
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return bignorm(z);
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}
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@ -1,7 +1,7 @@
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#define RUBY_VERSION "1.9.0"
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#define RUBY_RELEASE_DATE "2007-05-01"
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#define RUBY_RELEASE_DATE "2007-05-02"
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#define RUBY_VERSION_CODE 190
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#define RUBY_RELEASE_CODE 20070501
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#define RUBY_RELEASE_CODE 20070502
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#define RUBY_PATCHLEVEL 0
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#define RUBY_VERSION_MAJOR 1
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#define RUBY_VERSION_TEENY 0
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#define RUBY_RELEASE_YEAR 2007
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#define RUBY_RELEASE_MONTH 5
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#define RUBY_RELEASE_DAY 1
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#define RUBY_RELEASE_DAY 2
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#ifdef RUBY_EXTERN
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RUBY_EXTERN const char ruby_version[];
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