decode.c revision 50479 
1/*-
2 * Copyright (c) 1994 S�ren Schmidt
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 *    in this position and unchanged.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 *    derived from this software withough specific prior written permission
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef lint
30static const char rcsid[] =
31  "$FreeBSD: head/usr.sbin/vidcontrol/decode.c 50479 1999-08-28 01:35:59Z peter $";
32#endif /* not lint */
33
34#include <stdio.h>
35#include <string.h>
36#include "decode.h"
37
38int decode(FILE *fd, char *buffer)
39{
40	int n, pos = 0;
41	char *p;
42	char temp[128];
43
44#define	DEC(c)	(((c) - ' ') & 0x3f)
45
46	do {
47		if (!fgets(temp, sizeof(temp), fd))
48			return(0);
49	} while (strncmp(temp, "begin ", 6));
50	sscanf(temp, "begin %o %s", &n, temp);
51	for (;;) {
52		if (!fgets(p = temp, sizeof(temp), fd))
53			return(0);
54		if ((n = DEC(*p)) <= 0)
55			break;
56		for (++p; n > 0; p += 4, n -= 3)
57			if (n >= 3) {
58				buffer[pos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
59				buffer[pos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
60				buffer[pos++] = DEC(p[2])<<6 | DEC(p[3]);
61			}
62			else {
63				if (n >= 1) {
64					buffer[pos++] =
65						DEC(p[0])<<2 | DEC(p[1])>>4;
66				}
67				if (n >= 2) {
68					buffer[pos++] =
69						DEC(p[1])<<4 | DEC(p[2])>>2;
70				}
71				if (n >= 3) {
72					buffer[pos++] =
73						DEC(p[2])<<6 | DEC(p[3]);
74				}
75			}
76	}
77	if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
78		return(0);
79	return(pos);
80}
81