On 2015/4/28 17:35, Igor Mammedov wrote: > On Tue, 28 Apr 2015 16:52:19 +0800 > Shannon Zhao <zhaoshengl...@huawei.com> wrote: > >> On 2015/4/28 16:15, Igor Mammedov wrote: >>>>> btw: >>>>>>> whole thing might be simpler if an intermediate conversion is avoided, >>>>>>> just pack buffer as in spec byte by byte: >>>>>>> >>>>>>> /* format: aabbccdd-eeff-gghh-iijj-kkllmmnnoopp */ >>>>>>> assert(strlen(uuid) == ...); >>>>>>> build_append_byte(var->buf, HEX2BYTE(uuid[3]); /* dd */ >>>>> >>>>> use build_append_byte(var->buf, HEX2BYTE(uuid + 7); ? >>>>> >>>>>>> build_append_byte(var->buf, HEX2BYTE(uuid[2]); /* cc */ >>>>> >>>>> use build_append_byte(var->buf, HEX2BYTE(uuid + 5); ? >>> if you mean hyphens /-/ then they are not encoded, >>> but you surely can add checks for them to make sure that >>> UUID format is as expected. >>> >> >> I mean uuid[3] points to b not dd. Maybe use following way: >> >> static uint8_t Hex2Byte(char *src) > or even better: > Hex2Byte(char *src, byte_idx) > and do pointer arithmetic inside > > [...] >> build_append_byte(var->buf, Hex2Byte(uuid + (3 * 2))); /* dd */ > build_append_byte(var->buf, Hex2Byte(uuid, 3)); /* dd - at offset 00 */ > build_append_byte(var->buf, Hex2Byte(uuid, 2)); /* cc - at offset 01 */ > ... > Yes, it's better to first four bytes. But there are hyphens /-/, for offset 04, 05 and etc it doesn't work. We can't use following expression:
build_append_byte(var->buf, Hex2Byte(uuid, 5)); /* ff - at offset 04 */ build_append_byte(var->buf, Hex2Byte(uuid, 4)); /* ee - at offset 05 */ ...
