xref: /original-bsd/include/bitstring.h (revision c9004d80)
1 /*
2  * Copyright (c) 1989, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This code is derived from software contributed to Berkeley by
6  * Paul Vixie.
7  *
8  * %sccs.include.redist.c%
9  *
10  *	@(#)bitstring.h	8.1 (Berkeley) 07/19/93
11  */
12 
13 #ifndef _BITSTRING_H_
14 #define	_BITSTRING_H_
15 
16 typedef	unsigned char bitstr_t;
17 
18 /* internal macros */
19 				/* byte of the bitstring bit is in */
20 #define	_bit_byte(bit) \
21 	((bit) >> 3)
22 
23 				/* mask for the bit within its byte */
24 #define	_bit_mask(bit) \
25 	(1 << ((bit)&0x7))
26 
27 /* external macros */
28 				/* bytes in a bitstring of nbits bits */
29 #define	bitstr_size(nbits) \
30 	((((nbits) - 1) >> 3) + 1)
31 
32 				/* allocate a bitstring */
33 #define	bit_alloc(nbits) \
34 	(bitstr_t *)calloc(1, \
35 	    (unsigned int)bitstr_size(nbits) * sizeof(bitstr_t))
36 
37 				/* allocate a bitstring on the stack */
38 #define	bit_decl(name, nbits) \
39 	(name)[bitstr_size(nbits)]
40 
41 				/* is bit N of bitstring name set? */
42 #define	bit_test(name, bit) \
43 	((name)[_bit_byte(bit)] & _bit_mask(bit))
44 
45 				/* set bit N of bitstring name */
46 #define	bit_set(name, bit) \
47 	(name)[_bit_byte(bit)] |= _bit_mask(bit)
48 
49 				/* clear bit N of bitstring name */
50 #define	bit_clear(name, bit) \
51 	(name)[_bit_byte(bit)] &= ~_bit_mask(bit)
52 
53 				/* clear bits start ... stop in bitstring */
54 #define	bit_nclear(name, start, stop) { \
55 	register bitstr_t *_name = name; \
56 	register int _start = start, _stop = stop; \
57 	register int _startbyte = _bit_byte(_start); \
58 	register int _stopbyte = _bit_byte(_stop); \
59 	if (_startbyte == _stopbyte) { \
60 		_name[_startbyte] &= ((0xff >> (8 - (_start&0x7))) | \
61 				      (0xff << ((_stop&0x7) + 1))); \
62 	} else { \
63 		_name[_startbyte] &= 0xff >> (8 - (_start&0x7)); \
64 		while (++_startbyte < _stopbyte) \
65 			_name[_startbyte] = 0; \
66 		_name[_stopbyte] &= 0xff << ((_stop&0x7) + 1); \
67 	} \
68 }
69 
70 				/* set bits start ... stop in bitstring */
71 #define	bit_nset(name, start, stop) { \
72 	register bitstr_t *_name = name; \
73 	register int _start = start, _stop = stop; \
74 	register int _startbyte = _bit_byte(_start); \
75 	register int _stopbyte = _bit_byte(_stop); \
76 	if (_startbyte == _stopbyte) { \
77 		_name[_startbyte] |= ((0xff << (_start&0x7)) & \
78 				    (0xff >> (7 - (_stop&0x7)))); \
79 	} else { \
80 		_name[_startbyte] |= 0xff << ((_start)&0x7); \
81 		while (++_startbyte < _stopbyte) \
82 	    		_name[_startbyte] = 0xff; \
83 		_name[_stopbyte] |= 0xff >> (7 - (_stop&0x7)); \
84 	} \
85 }
86 
87 				/* find first bit clear in name */
88 #define	bit_ffc(name, nbits, value) { \
89 	register bitstr_t *_name = name; \
90 	register int _byte, _nbits = nbits; \
91 	register int _stopbyte = _bit_byte(_nbits), _value = -1; \
92 	for (_byte = 0; _byte <= _stopbyte; ++_byte) \
93 		if (_name[_byte] != 0xff) { \
94 			_value = _byte << 3; \
95 			for (_stopbyte = _name[_byte]; (_stopbyte&0x1); \
96 			    ++_value, _stopbyte >>= 1); \
97 			break; \
98 		} \
99 	*(value) = _value; \
100 }
101 
102 				/* find first bit set in name */
103 #define	bit_ffs(name, nbits, value) { \
104 	register bitstr_t *_name = name; \
105 	register int _byte, _nbits = nbits; \
106 	register int _stopbyte = _bit_byte(_nbits), _value = -1; \
107 	for (_byte = 0; _byte <= _stopbyte; ++_byte) \
108 		if (_name[_byte]) { \
109 			_value = _byte << 3; \
110 			for (_stopbyte = _name[_byte]; !(_stopbyte&0x1); \
111 			    ++_value, _stopbyte >>= 1); \
112 			break; \
113 		} \
114 	*(value) = _value; \
115 }
116 
117 #endif /* !_BITSTRING_H_ */
118