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SubjectRe: [RFCv3][PATCH 1/4] replace string_get_size() arrays
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On Fri, 2011-09-30 at 17:08 -0700, Dave Hansen wrote:
> Instead of explicitly storing the entire string for each
> possible units, just store the thing that varies: the
> first character.

trivia

> diff -puN lib/string_helpers.c~string_get_size-pow2 lib/string_helpers.c
> --- linux-2.6.git/lib/string_helpers.c~string_get_size-pow2 2011-09-30 16:50:31.628981352 -0700
> +++ linux-2.6.git-dave/lib/string_helpers.c 2011-09-30 17:04:02.211607364 -0700
> @@ -8,6 +8,23 @@
> #include <linux/module.h>
> #include <linux/string_helpers.h>
>
> +static const char byte_units[] = "_KMGTPEZY";

u64 could be up to ~1.8**19 decimal
zetta and yotta are not possible or necessary.
u128 maybe someday, but then other changes
would be necessary.

> +static char *__units_str(enum string_size_units unit, char *buf, int index)
> +{
> + int place = 0;
> +
> + /* index=0 is plain 'B' with no other unit */
> + if (index) {
> + buf[place++] = byte_units[index];

unbounded index (doesn't matter currently, it will for u128)

> @@ -23,26 +40,19 @@
> int string_get_size(u64 size, const enum string_size_units units,
> char *buf, int len)
[]
> const unsigned int divisor[] = {
> [STRING_UNITS_10] = 1000,
> [STRING_UNITS_2] = 1024,
> };

static const or it might be better to use
as that would make the code clearer.

unsigned int divisor = (string_size_units == STRING_UNITS_2) ? 1024 : 1000;

> @@ -61,7 +71,7 @@ int string_get_size(u64 size, const enum
> }
>
> snprintf(buf, len, "%lld%s %s", (unsigned long long)size,

%llu



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