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ctrl87.h
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ctrl87.h
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/*
* ctrl87.h
*
*/
#ifndef __CONTROL87_H__
#define __CONTROL87_H__
#ifdef __CONTROL87_C__
#define EXTERN
#else
#define EXTERN extern
#endif
/* 8087/80287 Status Word format */
#define SW_INVALID 0x0001 /* Invalid operation */
#define SW_DENORMAL 0x0002 /* Denormalized operand */
#define SW_ZERODIVIDE 0x0004 /* Zero divide */
#define SW_OVERFLOW 0x0008 /* Overflow */
#define SW_UNDERFLOW 0x0010 /* Underflow */
#define SW_INEXACT 0x0020 /* Precision (Inexact result) */
/* 8087/80287 Control Word format */
#define MCW_EM 0x003f /* interrupt Exception Masks*/
#define EM_INVALID 0x0001 /* invalid */
#define EM_DENORMAL 0x0002 /* denormal */
#define EM_ZERODIVIDE 0x0004 /* zero divide */
#define EM_OVERFLOW 0x0008 /* overflow */
#define EM_UNDERFLOW 0x0010 /* underflow */
#define EM_INEXACT 0x0020 /* inexact (precision) */
#define MCW_IC 0x1000 /* Infinity Control */
#define IC_AFFINE 0x1000 /* affine */
#define IC_PROJECTIVE 0x0000 /* projective */
#define MCW_RC 0x0c00 /* Rounding Control */
#define RC_CHOP 0x0c00 /* chop */
#define RC_UP 0x0800 /* up */
#define RC_DOWN 0x0400 /* down */
#define RC_NEAR 0x0000 /* near */
#define MCW_PC 0x0300 /* Precision Control */
#define PC_24 0x0000 /* 24 bits */
#define PC_53 0x0200 /* 53 bits */
#define PC_64 0x0300 /* 64 bits */
/**************************************************************************/
/************************* Type declarations **************************/
/**************************************************************************/
/**************************************************************************/
/************************ Function declarations ***********************/
/**************************************************************************/
/*
_control87 changes floating-point control word.
Declaration:
------------
unsigned short _control87(unsigned short newcw, unsigned short mask);
Remarks:
--------
_control87 retrieves or changes the floating-point control word.
The floating-point control word is an unsigned short that specifies the
following modes in the 80x87 FPU:
o allowed exceptions
o infinity mode
o rounding mode
o precision mode
Changing these modes allows you to mask or unmask floating-point exceptions.
_control87 matches the bits in mask to the bits in newcw.
If any mask bit = 1, the corresponding bit in newcw contains the new value
for the same bit in the floating-point control word.
If mask = 0000, _control87 returns the floating-point control word without
altering it.
Examples:
---------
Switching to projective infinity mode:
_control87(IC_PROJECTIVE, MCW_IC);
Disabling all exceptions:
_control87(MCW_EM, MCW_EM);
Return Value:
-------------
The bits in the value returned reflect the new floating-point control word.
*/
EXTERN unsigned short _control87(unsigned short newcw, unsigned short mask);
/**************************************************************************/
/************************** Global variables **************************/
/**************************************************************************/
#ifdef __CONTROL87_C__
#else
#endif
#undef EXTERN
#endif