Messages in this thread | | | Date | Tue, 19 Dec 2023 14:17:26 +1100 | From | David Disseldorp <> | Subject | Re: [PATCH 1/2] lib/strtox: introduce kstrtoull_suffix() helper |
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On Tue, 19 Dec 2023 06:22:42 +1030, Qu Wenruo wrote:
> On 2023/12/18 23:29, David Disseldorp wrote: > > Hi Qu, > > > > On Fri, 15 Dec 2023 19:09:23 +1030, Qu Wenruo wrote: > > > [...] > >> +/** > >> + * kstrtoull_suffix - convert a string to ull with suffixes support > >> + * @s: The start of the string. The string must be null-terminated, and may also > >> + * include a single newline before its terminating null. > >> + * @base: The number base to use. The maximum supported base is 16. If base is > >> + * given as 0, then the base of the string is automatically detected with the > >> + * conventional semantics - If it begins with 0x the number will be parsed as a > >> + * hexadecimal (case insensitive), if it otherwise begins with 0, it will be > >> + * parsed as an octal number. Otherwise it will be parsed as a decimal. > >> + * @res: Where to write the result of the conversion on success. > >> + * @suffixes: A string of acceptable suffixes, must be provided. Or caller > >> + * should use kstrtoull() directly. > > > > The suffixes parameter seems a bit cumbersome; callers need to provide > > both upper and lower cases, and unsupported characters aren't checked > > for. However, I can't think of any better suggestions at this stage. > > > > Initially I went bitmap for the prefixes, but it's not any better. > > Firstly where the bitmap should start. If we go bit 0 for "K", then the > code would introduce some difference between the bit number and left > shift (bit 0, left shift 10), which may be a little confusing. > > If we go bit 1 for "K", the bit and left shift it much better, but bit 0 > behavior would be left untouched. > > Finally the bitmap itself is not that straightforward.
One benefit from a bitmap would be that unsupported @suffixes are easier to detect (instead of ignored), but I think if you rename the function kstrtoull_unit_suffix() then it should be pretty clear what's supported.
> The limitation of providing both upper and lower case is due to the fact > that we don't have a case insensitive version of strchr(). > But I think it's not that to fix, just convert them all to lower or > upper case, then do the strchr(). > > Would accepting both cases for the suffixes be good enough?
I think so.
Cheers, David
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