4.4BSD/usr/src/sys/tahoe/math/FP.h

/*-
 * Copyright (c) 1985 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Computer Consoles Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)FP.h	7.1 (Berkeley) 12/6/90
 */

/*
 * General definitions of the floating point stuff on Power 6/32.
 * The floating point format definition is:
 *
 *		S    (exp-128)
 *	    (-1)  * 2	       * F
 *
 *	Where exp is the exponent field and F is the binary
 *	mantissa following it, including the hidden bit.
 *	The hidden bit actually is 1/2, so F is known to
 *	satisfy the range:
 *		1/2 <= F < 1
 */

typedef struct {
	unsigned	sign:1;
	unsigned	exponent:8;
	unsigned	mantissa:23;
} sp_format;

typedef struct {
	unsigned	sign:1;
	unsigned	exponent:8;
	unsigned	mantissa:23;
	unsigned	mantissa_lst;
} dp_format;

#define	EXP_BIAS	128		/* Exponent bias */
#define SIGN_BIT	0x80000000	/* S bit mask */