On 2015/5/4 17:22, Igor Mammedov wrote: > On Wed, 29 Apr 2015 21:41:39 +0800 > Shannon Zhao <shannon.z...@linaro.org> wrote: > >> >> >> On 2015/4/28 17:48, Shannon Zhao wrote: >>> 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 */ >>> ... >>> >>> >> >> So about the implementation of this macro, I think I'd like to use >> following approach. This lets Hex2Byte do what it should only do and >> still has a clear look of UUID. What do you think about? >> >> static uint8_t Hex2Byte(char *src) >> { >> int hi = Hex2Digit(*src++); >> int lo = Hex2Digit(*src); >> >> if ((hi < 0) || (lo < 0)) >> return -1; > just make Hex2Digit() assert on wrong input. >
Ok. >> >> return (hi << 4) | lo; >> } >> >> g_assert((strlen(uuid) == 36) && (uuid[8] == '-') && (uuid[13] == '-') >> && (uuid[18] == '-') && (uuid[23] == '-')); >> >> build_append_byte(var->buf, Hex2Byte(uuid + (3 * 2))); /* dd */ > ^^^^^ > I'd make it one number, instead of forcing reader to do math > every time he/she looks at this code. > Ok, will do this. And about other patches in this series could you offer your comments? Thanks, Shannon > >> build_append_byte(var->buf, Hex2Byte(uuid + (2 * 2))); /* cc */ >> build_append_byte(var->buf, Hex2Byte(uuid + (1 * 2))); /* bb */ >> build_append_byte(var->buf, Hex2Byte(uuid + (0 * 2))); /* aa */ >> >> build_append_byte(var->buf, Hex2Byte(uuid + (5 * 2 + 1))); /* ff */ >> build_append_byte(var->buf, Hex2Byte(uuid + (4 * 2 + 1))); /* ee */ >> >> build_append_byte(var->buf, Hex2Byte(uuid + (7 * 2 + 2))); /* hh */ >> build_append_byte(var->buf, Hex2Byte(uuid + (6 * 2 + 2))); /* gg */ >> >> build_append_byte(var->buf, Hex2Byte(uuid + (8 * 2 + 3))); /* ii */ >> build_append_byte(var->buf, Hex2Byte(uuid + (9 * 2 + 3))); /* jj */ >> >> build_append_byte(var->buf, Hex2Byte(uuid + (10 * 2 + 4))); /* kk */ >> build_append_byte(var->buf, Hex2Byte(uuid + (11 * 2 + 4))); /* ll */ >> build_append_byte(var->buf, Hex2Byte(uuid + (12 * 2 + 4))); /* mm */ >> build_append_byte(var->buf, Hex2Byte(uuid + (13 * 2 + 4))); /* nn */ >> build_append_byte(var->buf, Hex2Byte(uuid + (14 * 2 + 4))); /* oo */ >> build_append_byte(var->buf, Hex2Byte(uuid + (15 * 2 + 4))); /* pp */ >