decode.c revision 2089 
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 * 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 withough specific prior written permission
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 *
27 *	$Id: decode.c,v 1.1 1994/05/20 12:20:37 sos Exp $
28 */
29
30#include <stdio.h>
31
32int decode(FILE *fd, char *buffer)
33{
34	int n, pos = 0;
35	char *p;
36	char temp[128];
37
38#define	DEC(c)	(((c) - ' ') & 0x3f)
39
40	do {
41		if (!fgets(temp, sizeof(temp), fd))
42			return(0);
43	} while (strncmp(temp, "begin ", 6));
44	sscanf(temp, "begin %o %s", &n, temp);
45	for (;;) {
46		if (!fgets(p = temp, sizeof(temp), fd))
47			return(0);
48		if ((n = DEC(*p)) <= 0)
49			break;
50		for (++p; n > 0; p += 4, n -= 3)
51			if (n >= 3) {
52				buffer[pos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
53				buffer[pos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
54				buffer[pos++] = DEC(p[2])<<6 | DEC(p[3]);
55			}
56			else {
57				if (n >= 1) {
58					buffer[pos++] =
59						DEC(p[0])<<2 | DEC(p[1])>>4;
60				}
61				if (n >= 2) {
62					buffer[pos++] =
63						DEC(p[1])<<4 | DEC(p[2])>>2;
64				}
65				if (n >= 3) {
66					buffer[pos++] =
67						DEC(p[2])<<6 | DEC(p[3]);
68				}
69			}
70	}
71	if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
72		return(0);
73	return(pos);
74}
75