From ebbaec9696e6e567770a39adf0c25f92a82200c4 Mon Sep 17 00:00:00 2001 From: akr Date: Fri, 2 Aug 2013 15:55:07 +0000 Subject: * bignum.c (rb_big2str1): Simplify power_level calculation. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42341 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- ChangeLog | 4 ++++ bignum.c | 28 ++++++++++++++-------------- 2 files changed, 18 insertions(+), 14 deletions(-) diff --git a/ChangeLog b/ChangeLog index 864540cdcf..0f6cdd5acd 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +Sat Aug 3 00:52:43 2013 Tanaka Akira + + * bignum.c (rb_big2str1): Simplify power_level calculation. + Sat Aug 3 00:34:20 2013 Masaki Matsushita * array.c (rb_ary_zip): use rb_ary_new2() to create buffer diff --git a/bignum.c b/bignum.c index ded2d6b272..faedade1e4 100644 --- a/bignum.c +++ b/bignum.c @@ -4308,7 +4308,9 @@ big2str_karatsuba(struct big2str_struct *b2s, VALUE x, /* * Precondition: - * abs(x) < maxpow_in_bdigit_dbl(base, &numdigits)**(2**power_level) + * abs(x) < maxpow**(2**power_level) + * where + * maxpow = maxpow_in_bdigit_dbl(base, &numdigits) * * This function generates sequence of zeros, and then stringized abs(x) into b2s->ptr. * @@ -4453,22 +4455,20 @@ rb_big2str1(VALUE x, int base) power = power_cache_get_power(base, power_level, NULL); } assert(power_level != MAX_BIG2STR_TABLE_ENTRIES); - if (FIX2LONG(bary_cmp(BDIGITS(x), RBIGNUM_LEN(x), BDIGITS(power), RBIGNUM_LEN(power))) >= 0) { - power_level++; - } -#ifndef NDEBUG - if (0 < power_level) { - VALUE power1 = power_cache_get_power(base, power_level-1, NULL); - assert(FIX2LONG(bary_cmp(BDIGITS(x), RBIGNUM_LEN(x), BDIGITS(power1), RBIGNUM_LEN(power1))) >= 0); + if (RBIGNUM_LEN(power) <= RBIGNUM_LEN(x)) { /* - { - VALUE power0 = power_cache_get_power(base, power_level, NULL); - assert(FIX2LONG(bary_cmp(BDIGITS(x), RBIGNUM_LEN(x), BDIGITS(power0), RBIGNUM_LEN(power0))) < 0); - } - */ + * This increment guarantees x < power_cache_get_power(base, power_level) + * without invoking it actually. + * (power_cache_get_power(base, power_level) can be slow and not used + * in big2str_karatsuba.) + * + * Although it is possible that x < power_cache_get_power(base, power_level-1), + * it is no problem because big2str_karatsuba checks it and + * doesn't affect the result when b2s_data.ptr is NULL. + */ + power_level++; } -#endif b2s_data.negative = RBIGNUM_NEGATIVE_P(x); b2s_data.base = base; -- cgit v1.2.3