Coherent4.2.10/include/ieeefp.h

/* (-lgl
 *	Coherent 386 release 4.2
 *	Copyright (c) 1982, 1993 by Mark Williams Company.
 *	All rights reserved. May not be copied without permission.
 *	For copying permission and licensing info, write licensing@mwc.com
 -lgl) */

#ifndef __IEEEFP_H__
#define __IEEEFP_H__

/*
 * Describes the stack frame presented to a user signal handler,
 * including (optional) floating point context.
 */

/*
 * The following magic numbers index the "reg" part of a saved signal context.
 * These numbers *must* correspond to the structure offsets in the
 * <common/_gregset.h> header for this to work.
 */

#define	SS	18
#define	UESP	17
#define	EFL	16
#define	CS	15
#define	EIP	14
#define	ERR	13
#define TRAPNO	12
#define	EAX	11
#define	ECX	10
#define	EDX	9
#define	EBX	8
#define	ESP	7
#define	EBP	6
#define	ESI	5
#define	EDI	4
#define	DS	3
#define	ES	2
#define	FS	1
#define	GS	0


/*
 * "fpem" objects are for floating point emulation.
 *
 * The stackframe passed to a signal handler includes a pointer "fpsp".
 * This pointer is a (struct _fpstate *) when a true coprocessor is in use.
 * It is actually a (struct _fpemstate *), and must be cast thus, when
 * the emulator is used.
 * The declaration of "fpsp" is kept as (struct _fpstate *) for BCS
 * compatibility.
 */

struct _fpem_reg {
	char sign;
	char tag;
	long exp;
	unsigned sigl;
	unsigned sigh;
};

struct _fpstackframe {
	long	signo;
	long	regs[SS+1];
	struct	_fpstate *fpsp;
	char	*wsp;
};

struct _fpreg {
	unsigned short significand[4];
	unsigned short exponent;
};

struct _fpstate {
	unsigned long	cw,
			sw,
			tag,
			ipoff,
			cssel,
			dataoff,
			datasel;
	struct _fpreg	_st[8];
	unsigned long	status;
};

struct _fpemstate {
	unsigned long	cw,
			sw,
			tag,
			ipoff,
			cssel,
			dataoff,
			datasel,
			top;
	struct  _fpem_reg regs[8];	/* pseudo regs */
	unsigned char lookahead;
	unsigned long	status,
			entry_eip;
};

/* For kernel context in u area, which keeps either emulator or ndp status. */
union _fpcontext {
	struct _fpstate		fpstate;
	struct _fpemstate	fpemstate;
};

#endif