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[unix-history] / usr / src / lib / libc / quad / quad.h

/*-
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * %sccs.include.redist.c%
 *
 *	@(#)quad.h	8.1 (Berkeley) %G%
 */

/*
 * Quad arithmetic.
 *
 * This library makes the following assumptions:
 *
 *  - The type long long (aka quad_t) exists.
 *
 *  - A quad variable is exactly twice as long as `long'.
 *
 *  - The machine's arithmetic is two's complement.
 *
 * This library can provide 128-bit arithmetic on a machine with 128-bit
 * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
 * with 48-bit longs.
 */

#include <sys/types.h>
#include <limits.h>

/*
 * Depending on the desired operation, we view a `long long' (aka quad_t) in
 * one or more of the following formats.
 */
union uu {
	quad_t	q;		/* as a (signed) quad */
	quad_t	uq;		/* as an unsigned quad */
	long	sl[2];		/* as two signed longs */
	u_long	ul[2];		/* as two unsigned longs */
};

/*
 * Define high and low longwords.
 */
#define	H		_QUAD_HIGHWORD
#define	L		_QUAD_LOWWORD

/*
 * Total number of bits in a quad_t and in the pieces that make it up.
 * These are used for shifting, and also below for halfword extraction
 * and assembly.
 */
#define	QUAD_BITS	(sizeof(quad_t) * CHAR_BIT)
#define	LONG_BITS	(sizeof(long) * CHAR_BIT)
#define	HALF_BITS	(sizeof(long) * CHAR_BIT / 2)

/*
 * Extract high and low shortwords from longword, and move low shortword of
 * longword to upper half of long, i.e., produce the upper longword of
 * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
 *
 * These are used in the multiply code, to split a longword into upper
 * and lower halves, and to reassemble a product as a quad_t, shifted left
 * (sizeof(long)*CHAR_BIT/2).
 */
#define	HHALF(x)	((x) >> HALF_BITS)
#define	LHALF(x)	((x) & ((1 << HALF_BITS) - 1))
#define	LHUP(x)		((x) << HALF_BITS)

extern u_quad_t __qdivrem __P((u_quad_t u, u_quad_t v, u_quad_t *rem));

/*
 * XXX
 * Compensate for gcc 1 vs gcc 2.  Gcc 1 defines ?sh?di3's second argument
 * as u_quad_t, while gcc 2 correctly uses int.  Unfortunately, we still use
 * both compilers.
 */
#if __GNUC__ >= 2
typedef unsigned int	qshift_t;
#else
typedef u_quad_t	qshift_t;
#endif