/*      $NetBSD: convtbl.c,v 1.2 2016/08/02 17:53:46 scole Exp $        */

/*
* Copyright (c) 2003, Trent Nelson, <[email protected]>.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
*    derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: releng/10.1/usr.bin/systat/convtbl.c 175387 2008-01-16 19:27:43Z delphij $
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: convtbl.c,v 1.2 2016/08/02 17:53:46 scole Exp $");
#endif /* not lint */

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>

#include "convtbl.h"

#define BIT             (8)
#define BITS            (1)
#define KILOBIT         (1000LL)
#define MEGABIT         (KILOBIT * 1000)
#define GIGABIT         (MEGABIT * 1000)
#define TERABIT         (GIGABIT * 1000)

#define BYTE            (1)
#define BYTES           (1)
#define KILOBYTE        (1024LL)
#define MEGABYTE        (KILOBYTE * 1024)
#define GIGABYTE        (MEGABYTE * 1024)
#define TERABYTE        (GIGABYTE * 1024)

struct convtbl {
       uintmax_t        mul;
       uintmax_t        scale;
       const char      *str;
       const char      *name;
};

static struct convtbl convtbl[] = {
       /* mul, scale, str, name */
       [SC_BYTE] =     { BYTE, BYTES, "B", "byte" },
       [SC_KILOBYTE] = { BYTE, KILOBYTE, "KB", "kbyte" },
       [SC_MEGABYTE] = { BYTE, MEGABYTE, "MB", "mbyte" },
       [SC_GIGABYTE] = { BYTE, GIGABYTE, "GB", "gbyte" },
       [SC_TERABYTE] = { BYTE, TERABYTE, "TB", "tbyte" },

       [SC_BIT] =      { BIT, BITS, "b", "bit" },
       [SC_KILOBIT] =  { BIT, KILOBIT, "Kb", "kbit" },
       [SC_MEGABIT] =  { BIT, MEGABIT, "Mb", "mbit" },
       [SC_GIGABIT] =  { BIT, GIGABIT, "Gb", "gbit" },
       [SC_TERABIT] =  { BIT, TERABIT, "Tb", "tbit" },

       [SC_AUTO] =     { 0, 0, "", "auto" }
};

static
struct convtbl *
get_tbl_ptr(const uintmax_t size, const int scale)
{
       uintmax_t        tmp;
       int              idx;

       /* If our index is out of range, default to auto-scaling. */
       idx = scale < SC_AUTO ? scale : SC_AUTO;

       if (idx == SC_AUTO)
               /*
                * Simple but elegant algorithm.  Count how many times
                * we can shift our size value right by a factor of ten,
                * incrementing an index each time.  We then use the
                * index as the array index into the conversion table.
                */
               for (tmp = size, idx = SC_KILOBYTE;
                    tmp >= MEGABYTE && idx < SC_BIT - 1;
                    tmp >>= 10, idx++);

       return (&convtbl[idx]);
}

double
convert(const uintmax_t size, const int scale)
{
       struct convtbl  *tp;

       tp = get_tbl_ptr(size, scale);
       return ((double)size * tp->mul / tp->scale);

}

const char *
get_string(const uintmax_t size, const int scale)
{
       struct convtbl  *tp;

       tp = get_tbl_ptr(size, scale);
       return (tp->str);
}

int
get_scale(const char *name)
{
       int i;

       for (i = 0; i <= SC_AUTO; i++)
               if (strcmp(convtbl[i].name, name) == 0)
                       return (i);
       return (-1);
}

const char *
get_helplist(void)
{
       int i;
       size_t len;
       static char *buf;

       if (buf == NULL) {
               len = 0;
               for (i = 0; i <= SC_AUTO; i++)
                       len += strlen(convtbl[i].name) + 2;
               if ((buf = malloc(len)) != NULL) {
                       buf[0] = '\0';
                       for (i = 0; i <= SC_AUTO; i++) {
                               strcat(buf, convtbl[i].name);
                               if (i < SC_AUTO)
                                       strcat(buf, ", ");
                       }
               } else
                       return ("");
       }
       return (buf);
}