linux/lib/string_helpers.c
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   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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