xref: /freebsd/sys/libkern/quad.h (revision 17ee9d00bc1ae1e598c38f25826f861e4bc6c3ce)
1 /*-
2  * Copyright (c) 1992, 1993
3  *	The Regents of the University of California.  All rights reserved.
4  *
5  * This software was developed by the Computer Systems Engineering group
6  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7  * contributed to Berkeley.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. All advertising materials mentioning features or use of this software
18  *    must display the following acknowledgement:
19  *	This product includes software developed by the University of
20  *	California, Berkeley and its contributors.
21  * 4. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  *
37  *	@(#)quad.h	8.1 (Berkeley) 6/4/93
38  * $Id$
39  */
40 
41 /*
42  * Quad arithmetic.
43  *
44  * This library makes the following assumptions:
45  *
46  *  - The type long long (aka quad_t) exists.
47  *
48  *  - A quad variable is exactly twice as long as `long'.
49  *
50  *  - The machine's arithmetic is two's complement.
51  *
52  * This library can provide 128-bit arithmetic on a machine with 128-bit
53  * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
54  * with 48-bit longs.
55  */
56 
57 #include <sys/types.h>
58 #include <limits.h>
59 
60 /*
61  * Depending on the desired operation, we view a `long long' (aka quad_t) in
62  * one or more of the following formats.
63  */
64 union uu {
65 	quad_t	q;		/* as a (signed) quad */
66 	quad_t	uq;		/* as an unsigned quad */
67 	long	sl[2];		/* as two signed longs */
68 	u_long	ul[2];		/* as two unsigned longs */
69 };
70 
71 /*
72  * Define high and low longwords.
73  */
74 #define	H		_QUAD_HIGHWORD
75 #define	L		_QUAD_LOWWORD
76 
77 /*
78  * Total number of bits in a quad_t and in the pieces that make it up.
79  * These are used for shifting, and also below for halfword extraction
80  * and assembly.
81  */
82 #define	QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
83 #define	LONG_BITS	(sizeof(long) * CHAR_BIT)
84 #define	HALF_BITS	(sizeof(long) * CHAR_BIT / 2)
85 
86 /*
87  * Extract high and low shortwords from longword, and move low shortword of
88  * longword to upper half of long, i.e., produce the upper longword of
89  * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
90  *
91  * These are used in the multiply code, to split a longword into upper
92  * and lower halves, and to reassemble a product as a quad_t, shifted left
93  * (sizeof(long)*CHAR_BIT/2).
94  */
95 #define	HHALF(x)	((x) >> HALF_BITS)
96 #define	LHALF(x)	((x) & ((1 << HALF_BITS) - 1))
97 #define	LHUP(x)		((x) << HALF_BITS)
98 
99 extern u_quad_t __qdivrem __P((u_quad_t u, u_quad_t v, u_quad_t *rem));
100 
101 /*
102  * XXX
103  * Compensate for gcc 1 vs gcc 2.  Gcc 1 defines ?sh?di3's second argument
104  * as u_quad_t, while gcc 2 correctly uses int.  Unfortunately, we still use
105  * both compilers.
106  */
107 #if __GNUC__ >= 2
108 typedef unsigned int	qshift_t;
109 #else
110 typedef u_quad_t	qshift_t;
111 #endif
112