This is a specialized version of string_get_size().
It only works on powers-of-two, and only outputs in
KiB/MiB/etc... Doing it this way means that we do
not have to do any division like string_get_size()
does.
Signed-off-by: Dave Hansen <dave@xxxxxxxxxxxxxxxxxx>
---
linux-2.6.git-dave/include/linux/string_helpers.h | 1
linux-2.6.git-dave/lib/string_helpers.c | 23 ++++++++++++++++++++++
2 files changed, 24 insertions(+)
diff -puN lib/string_helpers.c~string_get_size-pow2-1 lib/string_helpers.c
--- linux-2.6.git/lib/string_helpers.c~string_get_size-pow2-1 2011-09-30 12:10:31.653729703 -0700
+++ linux-2.6.git-dave/lib/string_helpers.c 2011-09-30 12:40:13.090605408 -0700
@@ -21,6 +21,29 @@ static const unsigned int divisor[] = {
[STRING_UNITS_2] = 1024,
};
+u64 string_get_size_pow2(u64 size, const char **unit_ret)
+{
+ int log2;
+ int unit_index;
+
+ if (!size)
+ log2 = 0;
+ else
+ log2 = ilog2(size);
+
+ /* KiB is log2=0->9, MiB is 10->19, etc... */
+ unit_index = log2 / 10;
+ /* Can not overflow since YiB=2^80 does
+ * not fit in a u64. */
+ *unit_ret = units_2[unit_index];
+
+ /* 512 aka 2^9 is the largest integer without
+ * overflowing to the next power-of-two, so
+ * use %10 to make it max out there */
+ return (1 << (log2 % 10));
+}
+EXPORT_SYMBOL(string_get_size_pow2);
+
/**
* string_get_size - get the size in the specified units
* @size: The size to be converted
diff -puN include/linux/string_helpers.h~string_get_size-pow2-1 include/linux/string_helpers.h
--- linux-2.6.git/include/linux/string_helpers.h~string_get_size-pow2-1 2011-09-30 12:40:21.110592191 -0700
+++ linux-2.6.git-dave/include/linux/string_helpers.h 2011-09-30 12:40:31.186575591 -0700
@@ -10,6 +10,7 @@ enum string_size_units {
STRING_UNITS_2, /* use binary powers of 2^10 */
};
+u64 string_get_size_pow2(u64 size, const char **unit_ret);
int string_get_size(u64 size, enum string_size_units units,
char *buf, int len);
_
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