decode.c revision 23457 
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: decode.c,v 1.5 1997/02/22 16:14:07 peter Exp $
29 */
30
31#include <stdio.h>
32#include <string.h>
33#include "decode.h"
34
35int decode(FILE *fd, char *buffer)
36{
37	int n, pos = 0;
38	char *p;
39	char temp[128];
40
41#define	DEC(c)	(((c) - ' ') & 0x3f)
42
43	do {
44		if (!fgets(temp, sizeof(temp), fd))
45			return(0);
46	} while (strncmp(temp, "begin ", 6));
47	sscanf(temp, "begin %o %s", &n, temp);
48	for (;;) {
49		if (!fgets(p = temp, sizeof(temp), fd))
50			return(0);
51		if ((n = DEC(*p)) <= 0)
52			break;
53		for (++p; n > 0; p += 4, n -= 3)
54			if (n >= 3) {
55				buffer[pos++] = DEC(p[0])<<2 | DEC(p[1])>>4;
56				buffer[pos++] = DEC(p[1])<<4 | DEC(p[2])>>2;
57				buffer[pos++] = DEC(p[2])<<6 | DEC(p[3]);
58			}
59			else {
60				if (n >= 1) {
61					buffer[pos++] =
62						DEC(p[0])<<2 | DEC(p[1])>>4;
63				}
64				if (n >= 2) {
65					buffer[pos++] =
66						DEC(p[1])<<4 | DEC(p[2])>>2;
67				}
68				if (n >= 3) {
69					buffer[pos++] =
70						DEC(p[2])<<6 | DEC(p[3]);
71				}
72			}
73	}
74	if (!fgets(temp, sizeof(temp), fd) || strcmp(temp, "end\n"))
75		return(0);
76	return(pos);
77}
78