1/*****************************************************************************/
2/* */
3/* shift.h */
4/* */
5/* Safe shift routines */
6/* */
7/* */
8/* */
9/* (C) 2003 Ullrich von Bassewitz */
10/* Roemerstrasse 52 */
11/* D-70794 Filderstadt */
12/* EMail: uz@cc65.org */
13/* */
14/* */
15/* This software is provided 'as-is', without any expressed or implied */
16/* warranty. In no event will the authors be held liable for any damages */
17/* arising from the use of this software. */
18/* */
19/* Permission is granted to anyone to use this software for any purpose, */
20/* including commercial applications, and to alter it and redistribute it */
21/* freely, subject to the following restrictions: */
22/* */
23/* 1. The origin of this software must not be misrepresented; you must not */
24/* claim that you wrote the original software. If you use this software */
25/* in a product, an acknowledgment in the product documentation would be */
26/* appreciated but is not required. */
27/* 2. Altered source versions must be plainly marked as such, and must not */
28/* be misrepresented as being the original software. */
29/* 3. This notice may not be removed or altered from any source */
30/* distribution. */
31/* */
32/*****************************************************************************/
33
34
35
36/* According to the C standard, shifting a data type by the number of bits it
37** has causes undefined behaviour. So
38**
39** unsigned long l = 1;
40** unsigned u =32;
41** l <<= u;
42**
43** may be illegal. The functions in this module behave safely in that respect,
44** and they use proper casting to distinguish signed from unsigned shifts.
45** They are not a general purpose replacement for the shift operator!
46*/
47
48
49
50#ifndef SHIFT_H
51#define SHIFT_H
52
53
54
55#include <limits.h>
56
57
58
59/*****************************************************************************/
60/* Code */
61/*****************************************************************************/
62
63
64
65long asl_l (long l, unsigned count);
66/* Arithmetic shift left l by count. */
67
68long asr_l (long l, unsigned count);
69/* Arithmetic shift right l by count */
70
71unsigned long shl_l (unsigned long l, unsigned count);
72/* Logical shift left l by count */
73
74unsigned long shr_l (unsigned long l, unsigned count);
75/* Logical shift right l by count */
76
77
78
79/* End of shift.h */
80
81#endif
82