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Subject[RFCv3][PATCH 1/4] replace string_get_size() arrays
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Date

Instead of explicitly storing the entire string for each
possible units, just store the thing that varies: the
first character.

We have to special-case the 'B' unit (index==0).

This shaves about 100 bytes off of my .o file.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
---
linux-2.6.git-dave/lib/string_helpers.c | 30 ++++++++++++++++++++----------
1 file changed, 20 insertions(+), 10 deletions(-)
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";
+
+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];
+ if (unit == STRING_UNITS_2)
+ buf[place++] = 'i';
+ }
+ buf[place++] = 'B';
+ buf[place++] = '\0';
+ return buf;
+}
+
/**
* string_get_size - get the size in the specified units
* @size: The size to be converted
@@ -23,26 +40,19 @@
int string_get_size(u64 size, const enum string_size_units units,
char *buf, int len)
{
- const char *units_10[] = { "B", "kB", "MB", "GB", "TB", "PB",
- "EB", "ZB", "YB", NULL};
- const char *units_2[] = {"B", "KiB", "MiB", "GiB", "TiB", "PiB",
- "EiB", "ZiB", "YiB", NULL };
- const char **units_str[] = {
- [STRING_UNITS_10] = units_10,
- [STRING_UNITS_2] = units_2,
- };
const unsigned int divisor[] = {
[STRING_UNITS_10] = 1000,
[STRING_UNITS_2] = 1024,
};
int i, j;
u64 remainder = 0, sf_cap;
+ char unit_buf[4];
char tmp[8];

tmp[0] = '\0';
i = 0;
if (size >= divisor[units]) {
- while (size >= divisor[units] && units_str[units][i]) {
+ while (size >= divisor[units] && (i < strlen(byte_units))) {
remainder = do_div(size, divisor[units]);
i++;
}
@@ -61,7 +71,7 @@ int string_get_size(u64 size, const enum
}

snprintf(buf, len, "%lld%s %s", (unsigned long long)size,
- tmp, units_str[units][i]);
+ tmp, __units_str(units, unit_buf, i));

return 0;
}
diff -puN include/linux/string_helpers.h~string_get_size-pow2 include/linux/string_helpers.h
_


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