diff options
author | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2012-03-18 08:17:50 +0000 |
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committer | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2012-03-18 08:17:50 +0000 |
commit | ed4c5f38ba25e61a8c65abad4254317e253e36e8 (patch) | |
tree | 7b8786083cd7ded63c75b23f509b56641c3fd3e9 /bignum.c | |
parent | 2555f3f5bf0c2c343fdbec6c42570c781cbbe7c8 (diff) | |
download | ruby-ed4c5f38ba25e61a8c65abad4254317e253e36e8.tar.gz |
* bignum.c (rb_big_pow): estimate result bit size more precisely.
[ruby-core:30735][Feature #3429]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35081 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 7 |
1 files changed, 4 insertions, 3 deletions
@@ -3095,10 +3095,11 @@ rb_big_pow(VALUE x, VALUE y) else { VALUE z = 0; SIGNED_VALUE mask; - const long BIGLEN_LIMIT = 1024*1024 / SIZEOF_BDIGITS; + const long xlen = RBIGNUM_LEN(x) - 1; + const long xbits = ffs(RBIGNUM_DIGITS(x)[xlen]) + SIZEOF_BDIGITS*BITSPERDIG*xlen; + const long BIGLEN_LIMIT = BITSPERDIG*1024*1024; - if ((RBIGNUM_LEN(x) > BIGLEN_LIMIT) || - (RBIGNUM_LEN(x) > BIGLEN_LIMIT / yy)) { + if ((xbits > BIGLEN_LIMIT) || (xbits * yy > BIGLEN_LIMIT)) { rb_warn("in a**b, b may be too big"); d = (double)yy; break; |