convtbl.c revision 164672 
1/*
2 * Copyright (c) 2003, Trent Nelson, <trent@arpa.com>.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 *    derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * $FreeBSD: head/usr.bin/systat/convtbl.c 164672 2006-11-27 16:14:32Z yar $
29 */
30
31#include <sys/types.h>
32#include <stdlib.h>
33#include <string.h>
34#include "convtbl.h"
35
36struct	convtbl convtbl[] = {
37	/* mul, scale, str, name */
38	[SC_BYTE] =	{ BYTE, BYTES, "B",  "byte"  },
39	[SC_KILOBYTE] =	{ BYTE, KILO,  "KB", "kbyte" },
40	[SC_MEGABYTE] =	{ BYTE, MEGA,  "MB", "mbyte" },
41	[SC_GIGABYTE] =	{ BYTE, GIGA,  "GB", "gbyte" },
42
43	[SC_BIT] =	{ BIT, BITS, "b",  "bit"  },
44	[SC_KILOBIT] =	{ BIT, KILO, "Kb", "kbit" },
45	[SC_MEGABIT] =	{ BIT, MEGA, "Mb", "mbit" },
46	[SC_GIGABIT] =	{ BIT, GIGA, "Gb", "gbit" },
47
48	[SC_AUTO] =	{ 0, 0, "", "auto" }
49};
50
51static
52struct convtbl *
53get_tbl_ptr(const uintmax_t size, const int scale)
54{
55	uintmax_t	 tmp;
56	int		 idx;
57
58	/* If our index is out of range, default to auto-scaling. */
59	idx = scale < SC_AUTO ? scale : SC_AUTO;
60
61	if (idx == SC_AUTO)
62		/*
63		 * Simple but elegant algorithm.  Count how many times
64		 * we can shift our size value right by a factor of ten,
65		 * incrementing an index each time.  We then use the
66		 * index as the array index into the conversion table.
67		 */
68		for (tmp = size, idx = SC_KILOBYTE;
69		     tmp >= MEGA && idx < SC_GIGABYTE;
70		     tmp >>= 10, idx++);
71
72	return (&convtbl[idx]);
73}
74
75double
76convert(const uintmax_t size, const int scale)
77{
78	struct convtbl	*tp;
79
80	tp = get_tbl_ptr(size, scale);
81	return ((double)size * tp->mul / tp->scale);
82
83}
84
85const char *
86get_string(const uintmax_t size, const int scale)
87{
88	struct convtbl	*tp;
89
90	tp = get_tbl_ptr(size, scale);
91	return (tp->str);
92}
93
94int
95get_scale(const char *name)
96{
97	int i;
98
99	for (i = 0; i <= SC_AUTO; i++)
100		if (strcmp(convtbl[i].name, name) == 0)
101			return (i);
102	return (-1);
103}
104
105const char *
106get_helplist()
107{
108	int i;
109	size_t len;
110	static char *buf;
111
112	if (buf == NULL) {
113		len = 0;
114		for (i = 0; i <= SC_AUTO; i++)
115			len += strlen(convtbl[i].name) + 2;
116		if ((buf = malloc(len)) != NULL) {
117			buf[0] = '\0';
118			for (i = 0; i <= SC_AUTO; i++) {
119				strcat(buf, convtbl[i].name);
120				if (i < SC_AUTO)
121					strcat(buf, ", ");
122			}
123		} else
124			return ("");
125	}
126	return (buf);
127}
128