1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003, Trent Nelson, <trent@arpa.com>.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <sys/types.h>
32#include <stdlib.h>
33#include <string.h>
34#include "convtbl.h"
35
36#define BIT		(8)
37#define BITS		(1)
38#define KILOBIT		(1000LL)
39#define MEGABIT		(KILOBIT * 1000)
40#define GIGABIT		(MEGABIT * 1000)
41#define TERABIT		(GIGABIT * 1000)
42
43#define BYTE		(1)
44#define BYTES		(1)
45#define KILOBYTE	(1024LL)
46#define MEGABYTE	(KILOBYTE * 1024)
47#define GIGABYTE	(MEGABYTE * 1024)
48#define TERABYTE	(GIGABYTE * 1024)
49
50struct convtbl {
51	uintmax_t	 mul;
52	uintmax_t	 scale;
53	const char	*str;
54	const char	*name;
55};
56
57static struct convtbl convtbl[] = {
58	/* mul, scale, str, name */
59	[SC_BYTE] =	{ BYTE, BYTES, "B", "byte" },
60	[SC_KILOBYTE] =	{ BYTE, KILOBYTE, "KB", "kbyte" },
61	[SC_MEGABYTE] =	{ BYTE, MEGABYTE, "MB", "mbyte" },
62	[SC_GIGABYTE] =	{ BYTE, GIGABYTE, "GB", "gbyte" },
63	[SC_TERABYTE] =	{ BYTE, TERABYTE, "TB", "tbyte" },
64
65	[SC_BIT] =	{ BIT, BITS, "b", "bit" },
66	[SC_KILOBIT] =	{ BIT, KILOBIT, "Kb", "kbit" },
67	[SC_MEGABIT] =	{ BIT, MEGABIT, "Mb", "mbit" },
68	[SC_GIGABIT] =	{ BIT, GIGABIT, "Gb", "gbit" },
69	[SC_TERABIT] =	{ BIT, TERABIT, "Tb", "tbit" },
70
71	[SC_AUTO] =	{ 0, 0, "", "auto" }
72};
73
74static
75struct convtbl *
76get_tbl_ptr(const uintmax_t size, const int scale)
77{
78	uintmax_t	 tmp;
79	int		 idx;
80
81	/* If our index is out of range, default to auto-scaling. */
82	idx = scale < SC_AUTO ? scale : SC_AUTO;
83
84	if (idx == SC_AUTO)
85		/*
86		 * Simple but elegant algorithm.  Count how many times
87		 * we can shift our size value right by a factor of ten,
88		 * incrementing an index each time.  We then use the
89		 * index as the array index into the conversion table.
90		 */
91		for (tmp = size, idx = SC_KILOBYTE;
92		     tmp >= MEGABYTE && idx < SC_BIT - 1;
93		     tmp >>= 10, idx++);
94
95	return (&convtbl[idx]);
96}
97
98double
99convert(const uintmax_t size, const int scale)
100{
101	struct convtbl	*tp;
102
103	tp = get_tbl_ptr(size, scale);
104	return ((double)size * tp->mul / tp->scale);
105
106}
107
108const char *
109get_string(const uintmax_t size, const int scale)
110{
111	struct convtbl	*tp;
112
113	tp = get_tbl_ptr(size, scale);
114	return (tp->str);
115}
116
117int
118get_scale(const char *name)
119{
120	int i;
121
122	for (i = 0; i <= SC_AUTO; i++)
123		if (strcmp(convtbl[i].name, name) == 0)
124			return (i);
125	return (-1);
126}
127
128const char *
129get_helplist(void)
130{
131	int i;
132	size_t len;
133	static char *buf;
134
135	if (buf == NULL) {
136		len = 0;
137		for (i = 0; i <= SC_AUTO; i++)
138			len += strlen(convtbl[i].name) + 2;
139		if ((buf = malloc(len)) != NULL) {
140			buf[0] = '\0';
141			for (i = 0; i <= SC_AUTO; i++) {
142				strcat(buf, convtbl[i].name);
143				if (i < SC_AUTO)
144					strcat(buf, ", ");
145			}
146		} else
147			return ("");
148	}
149	return (buf);
150}
151