Root/lib/string_helpers.c

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 unsigned 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    i = 0;
44    if (size >= divisor[units]) {
45        while (size >= divisor[units] && units_str[units][i]) {
46            remainder = do_div(size, divisor[units]);
47            i++;
48        }
49
50        sf_cap = size;
51        for (j = 0; sf_cap*10 < 1000; j++)
52            sf_cap *= 10;
53
54        if (j) {
55            remainder *= 1000;
56            do_div(remainder, divisor[units]);
57            snprintf(tmp, sizeof(tmp), ".%03lld",
58                 (unsigned long long)remainder);
59            tmp[j+1] = '\0';
60        }
61    }
62
63    snprintf(buf, len, "%lld%s %s", (unsigned long long)size,
64         tmp, units_str[units][i]);
65
66    return 0;
67}
68EXPORT_SYMBOL(string_get_size);
69

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