xref: /freebsd/lib/libc/quad/quad.h (revision 06c3fb2749bda94cb5201f81ffdb8fa6c3161b2e)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This software was developed by the Computer Systems Engineering group
8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9  * contributed to Berkeley.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 /*
37  * Quad arithmetic.
38  *
39  * This library makes the following assumptions:
40  *
41  *  - The type long long (aka quad_t) exists.
42  *
43  *  - A quad variable is exactly twice as long as `long'.
44  *
45  *  - The machine's arithmetic is two's complement.
46  *
47  * This library can provide 128-bit arithmetic on a machine with 128-bit
48  * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
49  * with 48-bit longs.
50  */
51 
52 #include <sys/types.h>
53 #include <limits.h>
54 
55 /*
56  * Depending on the desired operation, we view a `long long' (aka quad_t) in
57  * one or more of the following formats.
58  */
59 union uu {
60 	quad_t	q;		/* as a (signed) quad */
61 	quad_t	uq;		/* as an unsigned quad */
62 	long	sl[2];		/* as two signed longs */
63 	u_long	ul[2];		/* as two unsigned longs */
64 };
65 
66 /*
67  * Define high and low longwords.
68  */
69 #define	H		_QUAD_HIGHWORD
70 #define	L		_QUAD_LOWWORD
71 
72 /*
73  * Total number of bits in a quad_t and in the pieces that make it up.
74  * These are used for shifting, and also below for halfword extraction
75  * and assembly.
76  */
77 #define	QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
78 #define	LONG_BITS	(sizeof(long) * CHAR_BIT)
79 #define	HALF_BITS	(sizeof(long) * CHAR_BIT / 2)
80 
81 /*
82  * Extract high and low shortwords from longword, and move low shortword of
83  * longword to upper half of long, i.e., produce the upper longword of
84  * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
85  *
86  * These are used in the multiply code, to split a longword into upper
87  * and lower halves, and to reassemble a product as a quad_t, shifted left
88  * (sizeof(long)*CHAR_BIT/2).
89  */
90 #define	HHALF(x)	((x) >> HALF_BITS)
91 #define	LHALF(x)	((x) & ((1L << HALF_BITS) - 1))
92 #define	LHUP(x)		((x) << HALF_BITS)
93 
94 int		__cmpdi2(quad_t a, quad_t b);
95 quad_t		__divdi3(quad_t a, quad_t b);
96 quad_t		__moddi3(quad_t a, quad_t b);
97 u_quad_t	__qdivrem(u_quad_t u, u_quad_t v, u_quad_t *rem);
98 int		__ucmpdi2(u_quad_t a, u_quad_t b);
99 u_quad_t	__udivdi3(u_quad_t a, u_quad_t b);
100 u_quad_t	__umoddi3(u_quad_t a, u_quad_t b);
101 
102 typedef unsigned int	qshift_t;
103