decode.c revision 22997 
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 *	$Id$
29 */
30
31#include <stdio.h>
32
33int decode(FILE *fd, char *buffer)
34{
35	int n, pos = 0;
36	char *p;
37	char temp[128];
38
39#define	DEC(c)	(((c) - ' ') & 0x3f)
40
41	do {
42		if (!fgets(temp, sizeof(temp), fd))
43			return(0);
44	} while (strncmp(temp, "begin ", 6));
45	sscanf(temp, "begin %o %s", &n, temp);
46	for (;;) {
47		if (!fgets(p = temp, sizeof(temp), fd))
48			return(0);
49		if ((n = DEC(*p)) <= 0)
50			break;
51		for (++p; n > 0; p += 4, n -= 3)
52			if (n >= 3) {
53				buffer[pos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
54				buffer[pos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
55				buffer[pos++] = DEC(p[2])<<6 | DEC(p[3]);
56			}
57			else {
58				if (n >= 1) {
59					buffer[pos++] =
60						DEC(p[0])<<2 | DEC(p[1])>>4;
61				}
62				if (n >= 2) {
63					buffer[pos++] =
64						DEC(p[1])<<4 | DEC(p[2])>>2;
65				}
66				if (n >= 3) {
67					buffer[pos++] =
68						DEC(p[2])<<6 | DEC(p[3]);
69				}
70			}
71	}
72	if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
73		return(0);
74	return(pos);
75}
76