diff options
author | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-06-09 20:39:05 +0000 |
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committer | akr <akr@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2013-06-09 20:39:05 +0000 |
commit | 192085bad3471ed7442a147f86a3c85c1958307c (patch) | |
tree | af94ea1af54081700de846cbe6ec64d2f86cb2aa /bignum.c | |
parent | 79042beeced5bc70183c405a8e2debbf6cd0bf70 (diff) |
* bignum.c (absint_numwords_small): New function.
(absint_numwords_generic): Use absint_numwords_small if possible.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41201 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'bignum.c')
-rw-r--r-- | bignum.c | 27 |
1 files changed, 25 insertions, 2 deletions
@@ -555,7 +555,7 @@ absint_numwords_bytes(size_t numbytes, int nlz_bits_in_msbyte, size_t word_numbi } else { s = q - 1; - t = word_numbits + r * CHAR_BIT - nlz_bits_in_msbyte; + t = word_numbits - nlz_bits_in_msbyte + r * CHAR_BIT; } div = s + t / word_numbits; mod = t % word_numbits; @@ -566,6 +566,20 @@ absint_numwords_bytes(size_t numbytes, int nlz_bits_in_msbyte, size_t word_numbi } size_t +absint_numwords_small(size_t numbytes, int nlz_bits_in_msbyte, size_t word_numbits, size_t *nlz_bits_ret) +{ + size_t val_numbits = numbytes * CHAR_BIT - nlz_bits_in_msbyte; + size_t div = val_numbits / word_numbits; + size_t mod = val_numbits % word_numbits; + size_t numwords; + size_t nlz_bits; + numwords = mod == 0 ? div : div + 1; + nlz_bits = mod == 0 ? 0 : word_numbits - mod; + *nlz_bits_ret = nlz_bits; + return numwords; +} + +size_t absint_numwords_generic(size_t numbytes, int nlz_bits_in_msbyte, size_t word_numbits, size_t *nlz_bits_ret) { VALUE val_numbits, word_numbits_v; @@ -634,7 +648,16 @@ rb_absint_numwords(VALUE val, size_t word_numbits, size_t *nlz_bits_ret) numbytes = rb_absint_size(val, &nlz_bits_in_msbyte); - if (word_numbits % CHAR_BIT == 0) { + if (numbytes <= SIZE_MAX / CHAR_BIT) { + numwords = absint_numwords_small(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits); +#if 0 + size_t numwords0, nlz_bits0; + numwords0 = absint_numwords_generic(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits0); + assert(numwords0 == numwords); + assert(nlz_bits0 == nlz_bits); +#endif + } + else if (word_numbits % CHAR_BIT == 0) { numwords = absint_numwords_bytes(numbytes, nlz_bits_in_msbyte, word_numbits, &nlz_bits); #if 0 size_t numwords0, nlz_bits0; |