xref: /csrg-svn/lib/libc/quad/quad.h (revision 61160)
153439Sbostic /*-
2*61160Sbostic  * Copyright (c) 1992, 1993
3*61160Sbostic  *	The Regents of the University of California.  All rights reserved.
453439Sbostic  *
553794Sbostic  * This software was developed by the Computer Systems Engineering group
653794Sbostic  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
753794Sbostic  * contributed to Berkeley.
853794Sbostic  *
953439Sbostic  * %sccs.include.redist.c%
1053795Sbostic  *
11*61160Sbostic  *	@(#)quad.h	8.1 (Berkeley) 06/04/93
1253794Sbostic  */
1353794Sbostic 
1453794Sbostic /*
1553794Sbostic  * Quad arithmetic.
1653439Sbostic  *
1753794Sbostic  * This library makes the following assumptions:
1853794Sbostic  *
1954431Sbostic  *  - The type long long (aka quad_t) exists.
2053794Sbostic  *
2153794Sbostic  *  - A quad variable is exactly twice as long as `long'.
2253794Sbostic  *
2353794Sbostic  *  - The machine's arithmetic is two's complement.
2453794Sbostic  *
2554431Sbostic  * This library can provide 128-bit arithmetic on a machine with 128-bit
2654431Sbostic  * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
2754431Sbostic  * with 48-bit longs.
2853439Sbostic  */
2953439Sbostic 
3054431Sbostic #include <sys/types.h>
3153794Sbostic #include <limits.h>
3253459Sbostic 
3353794Sbostic /*
3454431Sbostic  * Depending on the desired operation, we view a `long long' (aka quad_t) in
3553794Sbostic  * one or more of the following formats.
3653794Sbostic  */
3753794Sbostic union uu {
3854431Sbostic 	quad_t	q;		/* as a (signed) quad */
3954431Sbostic 	quad_t	uq;		/* as an unsigned quad */
4053794Sbostic 	long	sl[2];		/* as two signed longs */
4153794Sbostic 	u_long	ul[2];		/* as two unsigned longs */
4253794Sbostic };
4353459Sbostic 
4453794Sbostic /*
4553794Sbostic  * Define high and low longwords.
4653794Sbostic  */
4753794Sbostic #define	H		_QUAD_HIGHWORD
4853794Sbostic #define	L		_QUAD_LOWWORD
4953459Sbostic 
5053794Sbostic /*
5154431Sbostic  * Total number of bits in a quad_t and in the pieces that make it up.
5253794Sbostic  * These are used for shifting, and also below for halfword extraction
5353794Sbostic  * and assembly.
5453794Sbostic  */
5554431Sbostic #define	QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
5653794Sbostic #define	LONG_BITS	(sizeof(long) * CHAR_BIT)
5753794Sbostic #define	HALF_BITS	(sizeof(long) * CHAR_BIT / 2)
5853459Sbostic 
5953794Sbostic /*
6053794Sbostic  * Extract high and low shortwords from longword, and move low shortword of
6153794Sbostic  * longword to upper half of long, i.e., produce the upper longword of
6254431Sbostic  * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
6353794Sbostic  *
6453794Sbostic  * These are used in the multiply code, to split a longword into upper
6554431Sbostic  * and lower halves, and to reassemble a product as a quad_t, shifted left
6653794Sbostic  * (sizeof(long)*CHAR_BIT/2).
6753794Sbostic  */
6853794Sbostic #define	HHALF(x)	((x) >> HALF_BITS)
6953794Sbostic #define	LHALF(x)	((x) & ((1 << HALF_BITS) - 1))
7053794Sbostic #define	LHUP(x)		((x) << HALF_BITS)
7153439Sbostic 
7254431Sbostic extern u_quad_t __qdivrem __P((u_quad_t u, u_quad_t v, u_quad_t *rem));
7354182Sbostic 
7454182Sbostic /*
7554182Sbostic  * XXX
7654182Sbostic  * Compensate for gcc 1 vs gcc 2.  Gcc 1 defines ?sh?di3's second argument
7754431Sbostic  * as u_quad_t, while gcc 2 correctly uses int.  Unfortunately, we still use
7854182Sbostic  * both compilers.
7954182Sbostic  */
8055768Sbostic #if __GNUC__ >= 2
8154182Sbostic typedef unsigned int	qshift_t;
8254182Sbostic #else
8354431Sbostic typedef u_quad_t	qshift_t;
8454182Sbostic #endif
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