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author | duerst <duerst@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2014-10-26 02:24:28 +0000 |
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committer | duerst <duerst@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2014-10-26 02:24:28 +0000 |
commit | d26c49657db909ccfa4434bdc975a3278db749fc (patch) | |
tree | 96feaae18d862185b15216921bd7d775fe3c2c20 /string.c | |
parent | 26d56b7dc87600c560672c582f1785a21e10fa45 (diff) | |
download | ruby-d26c49657db909ccfa4434bdc975a3278db749fc.tar.gz |
string.c: improved comment.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48142 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'string.c')
-rw-r--r-- | string.c | 13 |
1 files changed, 7 insertions, 6 deletions
@@ -1187,26 +1187,27 @@ rb_str_init(int argc, VALUE *argv, VALUE str) /* * UTF-8 leading bytes have either 0xxxxxxx or 11xxxxxx * bit representation. (see http://en.wikipedia.org/wiki/UTF-8) - * Therefore, following pseudo code can detect UTF-8 leading byte. + * Therefore, the following pseudocode can detect UTF-8 leading bytes. * * if (!(byte & 0x80)) * byte |= 0x40; // turn on bit6 - * return ((byte>>6) & 1); // bit6 represent it's leading byte or not. + * return ((byte>>6) & 1); // bit6 represent whether this byte is leading or not. * - * This function calculate every bytes in the argument word `s' - * using the above logic concurrently. and gather every bytes result. + * This function calculates whether a byte is leading or not for all bytes + * in the argument word by concurrently using the above logic, and then + * adds up the number of leading bytes in the word. */ static inline uintptr_t count_utf8_lead_bytes_with_word(const uintptr_t *s) { uintptr_t d = *s; - /* Transform into bit0 represent UTF-8 leading or not. */ + /* Transform so that bit0 indicates whether we have a UTF-8 leading byte or not. */ d |= ~(d>>1); d >>= 6; d &= NONASCII_MASK >> 7; - /* Gather every bytes. */ + /* Gather all bytes. */ d += (d>>8); d += (d>>16); #if SIZEOF_VOIDP == 8 |