root/lib/string_helpers.c

DEFINITIONS

1. string_get_size

/*
 * Helpers for formatting and printing strings
 *
 * Copyright 31 August 2008 James Bottomley
 */
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/string_helpers.h>

/**
 * string_get_size - get the size in the specified units
 * @size:       The size to be converted
 * @units:      units to use (powers of 1000 or 1024)
 * @buf:        buffer to format to
 * @len:        length of buffer
 *
 * This function returns a string formatted to 3 significant figures
 * giving the size in the required units.  Returns 0 on success or
 * error on failure.  @buf is always zero terminated.
 *
 */
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 int divisor[] = {
                [STRING_UNITS_10] = 1000,
                [STRING_UNITS_2] = 1024,
        };
        int i, j;
        u64 remainder = 0, sf_cap;
        char tmp[8];

        tmp[0] = '\0';

        for (i = 0; size > divisor[units] && units_str[units][i]; i++)
                remainder = do_div(size, divisor[units]);

        sf_cap = size;
        for (j = 0; sf_cap*10 < 1000; j++)
                sf_cap *= 10;

        if (j) {
                remainder *= 1000;
                do_div(remainder, divisor[units]);
                snprintf(tmp, sizeof(tmp), ".%03lld",
                         (unsigned long long)remainder);
                tmp[j+1] = '\0';
        }

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

        return 0;
}
EXPORT_SYMBOL(string_get_size);