xref: /titanic_51/usr/src/head/ieeefp.h (revision ba3594ba9b5dd4c846c472a8d657edcb7c8109ac)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1988 AT&T */
/*	  All Rights Reserved */


#ifndef _IEEEFP_H
#define	_IEEEFP_H

#ifdef	__cplusplus
extern "C" {
#endif

/*
 * Floating point enviornment for machines that support
 * the IEEE 754 floating-point standard.  This file currently
 * supports the 80*87, and SPARC families.
 *
 * This header defines the following interfaces:
 *	1) Classes of floating point numbers
 *	2) Rounding Control
 *	3) Exception Control
 *	4) Exception Handling
 *	5) Utility Macros
 *	6) Full Exception Environment Control
 */

/*
 * CLASSES of floating point numbers *************************
 * IEEE floating point values fall into 1 of the following 10
 * classes
 */
typedef	enum	fpclass_t {
	FP_SNAN = 0,	/* signaling NaN */
	FP_QNAN = 1,	/* quiet NaN */
	FP_NINF = 2,	/* negative infinity */
	FP_PINF = 3,	/* positive infinity */
	FP_NDENORM = 4, /* negative denormalized non-zero */
	FP_PDENORM = 5, /* positive denormalized non-zero */
	FP_NZERO = 6,	/* -0.0 */
	FP_PZERO = 7,   /* +0.0 */
	FP_NNORM = 8,	/* negative normalized non-zero */
	FP_PNORM = 9	/* positive normalized non-zero */
} fpclass_t;

extern fpclass_t fpclass(double);	/* get class of double value */
extern int	finite(double);
extern int	unordered(double, double);

/*
 * ROUNDING CONTROL ******************************************
 *
 * At all times, floating-point math is done using one of four
 * mutually-exclusive rounding modes.
 */

#if defined(__i386) || defined(__amd64)

/*
 * NOTE: the values given are chosen to match those used by the
 * 80*87 rounding mode field in the control word.
 */
typedef	enum	fp_rnd {
	FP_RN = 0,	/* round to nearest representable number, tie -> even */
	FP_RM = 1,	/* round toward minus infinity */
	FP_RP = 2,	/* round toward plus infinity */
	FP_RZ = 3	/* round toward zero (truncate) */
} fp_rnd;

#endif

#if defined(__sparc)

/*
 * NOTE: the values given are chosen to match those used by the
 * RD (Round Direction) field of the FSR (Floating Point State Register).
 */
typedef	enum	fp_rnd {
	FP_RN = 0,	/* round to nearest representable number, tie -> even */
	FP_RZ = 1,	/* round toward zero (truncate) */
	FP_RP = 2,	/* round toward plus infinity */
	FP_RM = 3	/* round toward minus infinity */
} fp_rnd;

#endif

extern fp_rnd	fpsetround(fp_rnd);	/* set rounding mode, return previous */
extern fp_rnd	fpgetround(void);	/* return current rounding mode */

/*
 * EXCEPTION CONTROL *****************************************
 *
 */

#define	fp_except	int

#define	FP_DISABLE	0	/* exception will be ignored */
#define	FP_ENABLE	1	/* exception will cause SIGFPE */
#define	FP_CLEAR	0	/* exception has not occurred */
#define	FP_SET		1	/* exception has occurred */

#if defined(__i386) || defined(__amd64)

/*
 * There are six floating point exceptions, which can be individually
 * ENABLED (== 1) or DISABLED (== 0).  When an exception occurs
 * (ENABLED or not), the fact is noted by changing an associated
 * "sticky bit" from CLEAR (==0) to SET (==1).
 *
 * NOTE: the bit positions in fp_except are chosen to match those of
 * the 80*87 control word mask bits.  Although the 87 chips actually
 * ENABLE exceptions with a mask value of 0 (not 1, as on the 3b), it
 * is felt that switching these values may create more problems than
 * it solves.
 */

/* an fp_except can have the following (not exclusive) values: */
#define	FP_X_INV	0x01	/* invalid operation exception */
#define	FP_X_DNML	0x02	/* denormalization exception */
#define	FP_X_DZ		0x04	/* divide-by-zero exception */
#define	FP_X_OFL	0x08	/* overflow exception */
#define	FP_X_UFL	0x10	/* underflow exception */
#define	FP_X_IMP	0x20	/* imprecise (loss of precision) */

#endif

#if defined(__sparc)

/*
 * There are five floating-point exceptions, which can be individually
 * ENABLED (== 1) or DISABLED (== 0).  When an exception occurs
 * (ENABLED or not), the fact is noted by changing an associated
 * "sticky bit" from CLEAR (==0) to SET (==1).
 *
 * NOTE: the bit positions in an fp_except are chosen to match that in
 * the Trap Enable Mask of the FSR (Floating Point State Register).
 */

/* an fp_except can have the following (not exclusive) values: */
#define	FP_X_INV	0x10	/* invalid operation exception */
#define	FP_X_OFL	0x08	/* overflow exception */
#define	FP_X_UFL	0x04	/* underflow exception */
#define	FP_X_DZ		0x02	/* divide-by-zero exception */
#define	FP_X_IMP	0x01	/* imprecise (loss of precision) */

#endif

extern fp_except fpgetmask(void);		/* current exception mask */
extern fp_except fpsetmask(fp_except);		/* set mask, return previous */
extern fp_except fpgetsticky(void);		/* return logged exceptions */
extern fp_except fpsetsticky(fp_except);	/* change logged exceptions */

/*
 * UTILITY MACROS ********************************************
 */

extern int isnanf(float);
extern int isnand(double);

#if defined(__i386) || defined(__amd64)

/*
 * EXCEPTION HANDLING ****************************************
 *
 * When a signal handler catches an FPE, it will have a freshly initialized
 * coprocessor.  This allows signal handling routines to make use of
 * floating point arithmetic, if need be.  The previous state of the 87
 * chip is available, however.  There are two ways to get at this information,
 * depending on how the signal handler was set up.
 *
 * If the handler was set via signal() or sigset(), the old, SVR3, method
 * should be used: the signal handler assumes that it has a single parameter,
 * which is of type struct _fpstackframe, defined below.  By investigating
 * this parameter, the cause of the FPE may be determined.  By modifying it,
 * the state of the coprocessor can be changed upon return to the main task.
 * THIS METHOD IS OBSOLETE, AND MAY NOT BE SUPPORTED IN FUTURE RELEASES.
 *
 * If the handler was set via sigaction(), the new, SVR4, method should be
 * used: the third argument to the handler will be a pointer to a ucontext
 * structure (see sys/ucontext.h).  The uc_mcontext.fpregs member of the
 * ucontext structure holds the saved floating-point registers.  This can be
 * examined and/or modified.  By modifying it, the state of the coprocessor
 * can be changed upon return to the main task.
 */

struct _fpreg {	/* structure of a temp real fp register */
	unsigned short significand[4];	/* 64 bit mantissa value */
	unsigned short exponent;	/* 15 bit exponent and sign bit */
};

#if defined(__i386)

/*
 * AMD64 users should use sigaction() as described above.
 */

struct _fpstackframe {		/* signal handler's argument */
	long signo;		/* signal number arg */
	long regs[19];		/* all registers */
	struct _fpstate *fpsp;	/* address of saved 387 state */
	char *wsp;		/* address of saved Weitek state */
};

#endif

#if defined(__i386) || defined(__amd64)

#if defined(__amd64)
#define	_fpstate _fpstate32
#endif

struct _fpstate {		/* saved state info from an exception */
	unsigned int	cw,	/* control word */
			sw,	/* status word after fnclex-not useful */
			tag,	/* tag word */
			ipoff,	/* %eip register */
			cssel,	/* code segment selector */
			dataoff, /* data operand address */
			datasel; /* data operand selector */
	struct _fpreg _st[8];	/* saved register stack */
	unsigned int status;	/* status word saved at exception */
	unsigned int mxcsr;
	unsigned int xstatus;	/* status word saved at exception */
	unsigned int __pad[2];
	unsigned int xmm[8][4];
};

#if defined(__amd64)
#undef	_fpstate
#endif

#endif	/* __i386 || __amd64 */

/*
 * The structure of the 80*87 status and control words, and the mxcsr
 * register are given by the following structures.
 */
struct _cw87 {
	unsigned
		mask:	6,	/* exception masks */
		res1:	2,	/* not used */
		prec:	2,	/* precision control field */
		rnd:	2,	/* rounding control field */
		inf:	1,	/* infinity control (not on 387) */
		res2:	3;	/* not used */
};

struct _sw87 {
	unsigned
		excp:	6,	/* exception sticky bits */
		res1:	1,	/* not used */
		errs:	1,	/* error summary-set if unmasked excp */
		c012:	3,	/* condition code bits 0..2 */
		stkt:	3,	/* stack top pointer */
		c3:	1,	/* condition code bit 3 */
		busy:	1;	/* coprocessor busy */
};

struct _mxcsr {
	unsigned
		excp:	6,	/* exception sticky bits */
		daz:	1,	/* denormals are zeroes */
		mask:	6,	/* exception masks */
		rnd:	2,	/* rounding control */
		fzero:	1;	/* flush to zero */
};

#endif

#ifdef	__cplusplus
}
#endif

#endif	/* _IEEEFP_H */