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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2008-08-31 11:13:54 -0400
committerJames Bottomley <James.Bottomley@HansenPartnership.com>2008-10-03 12:46:14 -0400
commit3c9f3681d0b4af09c1cbf04f92fdfb72bd81ad7b (patch)
tree64afe14ce916e5202d1c92b776883d2039b092eb /lib/string_helpers.c
parent114f1ea408944f9515e45aa7452238fb15a1fa00 (diff)
[SCSI] lib: add generic helper to print sizes rounded to the correct SI range
This patch adds the ability to print sizes in either units of 10^3 (SI) or 2^10 (Binary) units. It rounds up to three significant figures and can be used for either memory or storage capacities. Oh, and I'm fully aware that 64 bits is only 16EiB ... the Zetta and Yotta units are added for future proofing against the day we have 128 bit computers ... [fujita.tomonori@lab.ntt.co.jp: fix missed unsigned long long cast] Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Diffstat (limited to 'lib/string_helpers.c')
-rw-r--r--lib/string_helpers.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
new file mode 100644
index 000000000000..8347925030ff
--- /dev/null
+++ b/lib/string_helpers.c
@@ -0,0 +1,64 @@
1/*
2 * Helpers for formatting and printing strings
3 *
4 * Copyright 31 August 2008 James Bottomley
5 */
6#include <linux/kernel.h>
7#include <linux/math64.h>
8#include <linux/module.h>
9#include <linux/string_helpers.h>
10
11/**
12 * string_get_size - get the size in the specified units
13 * @size: The size to be converted
14 * @units: units to use (powers of 1000 or 1024)
15 * @buf: buffer to format to
16 * @len: length of buffer
17 *
18 * This function returns a string formatted to 3 significant figures
19 * giving the size in the required units. Returns 0 on success or
20 * error on failure. @buf is always zero terminated.
21 *
22 */
23int string_get_size(u64 size, const enum string_size_units units,
24 char *buf, int len)
25{
26 const char *units_10[] = { "B", "KB", "MB", "GB", "TB", "PB",
27 "EB", "ZB", "YB", NULL};
28 const char *units_2[] = {"B", "KiB", "MiB", "GiB", "TiB", "PiB",
29 "EiB", "ZiB", "YiB", NULL };
30 const char **units_str[] = {
31 [STRING_UNITS_10] = units_10,
32 [STRING_UNITS_2] = units_2,
33 };
34 const int divisor[] = {
35 [STRING_UNITS_10] = 1000,
36 [STRING_UNITS_2] = 1024,
37 };
38 int i, j;
39 u64 remainder = 0, sf_cap;
40 char tmp[8];
41
42 tmp[0] = '\0';
43
44 for (i = 0; size > divisor[units] && units_str[units][i]; i++)
45 remainder = do_div(size, divisor[units]);
46
47 sf_cap = size;
48 for (j = 0; sf_cap*10 < 1000; j++)
49 sf_cap *= 10;
50
51 if (j) {
52 remainder *= 1000;
53 do_div(remainder, divisor[units]);
54 snprintf(tmp, sizeof(tmp), ".%03lld",
55 (unsigned long long)remainder);
56 tmp[j+1] = '\0';
57 }
58
59 snprintf(buf, len, "%lld%s%s", (unsigned long long)size,
60 tmp, units_str[units][i]);
61
62 return 0;
63}
64EXPORT_SYMBOL(string_get_size);