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* bignum.c (rb_big2str1): Simplify power_level calculation.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42341 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
akr 2013-08-02 15:55:07 +00:00
parent 633fd55c4c
commit ebbaec9696
2 changed files with 19 additions and 15 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
Sat Aug 3 00:52:43 2013 Tanaka Akira <akr@fsij.org>
* bignum.c (rb_big2str1): Simplify power_level calculation.
Sat Aug 3 00:34:20 2013 Masaki Matsushita <glass.saga@gmail.com>
* array.c (rb_ary_zip): use rb_ary_new2() to create buffer

30
bignum.c
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@ -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.
*
@ -4453,23 +4455,21 @@ 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) {
if (RBIGNUM_LEN(power) <= RBIGNUM_LEN(x)) {
/*
* 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++;
}
#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);
/*
{
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);
}
*/
}
#endif
b2s_data.negative = RBIGNUM_NEGATIVE_P(x);
b2s_data.base = base;
b2s_data.hbase = maxpow_in_bdigit(base, &b2s_data.hbase_numdigits);