Source code of Windows XP (NT5)
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/***
*ieee.c - ieee control and status routines** Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.**Purpose:* IEEE control and status routines.**Revision History:** 04-01-02 GDP Rewritten to use abstract control and status words* 06-06-01 GB Added _DN_FLUSH**/
#ifndef _IA64_
#define _IA64_
#endif
#include <trans.h>
#include <float.h>
#include <nt.h>
#include <signal.h>
extern unsigned __int64 _get_fpsr(void);extern void _set_fpsr(unsigned __int64);extern void _fclrf(void);
static unsigned int _abstract_sw(unsigned __int64 sw);static unsigned int _abstract_cw(unsigned __int64 cw);static unsigned __int64 _hw_cw(unsigned int abstr);
#define FS (1<<6)
#define CWMASK 0x00001f7f
#define FTZ 0x00000040
/***
* _statusfp() -**Purpose:* return abstract fp status word**Entry:**Exit:**Exceptions:********************************************************************************/
unsigned int _statusfp(){ unsigned __int64 status;
status = _get_fpsr();
return _abstract_sw(status);}
/***
*_clearfp() -**Purpose:* return abstract status word and clear status**Entry:**Exit:**Exceptions:********************************************************************************/
unsigned int _clearfp(){ unsigned __int64 status;
status = _get_fpsr(); _fclrf();
return _abstract_sw(status);}
/*** _control87
*() -**Purpose:* return and set abstract user fp control word* can modify EM_DENORMAL mask**Entry:**Exit:**Exceptions:********************************************************************************/
unsigned int _control87(unsigned int newctrl, unsigned int mask){ unsigned __int64 oldCw; unsigned __int64 newCw; unsigned int oldabs; unsigned int newabs;
oldCw = _get_fpsr();
oldabs = _abstract_cw(oldCw);
newabs = (newctrl & mask) | (oldabs & ~mask);
newCw = _hw_cw(newabs) | (oldCw & ~(unsigned __int64)CWMASK);
_set_fpsr(newCw);
return newabs;} /* _control87() */
/*** _controlfp
*() -**Purpose:* return and set abstract user fp control word* cannot change denormal mask (ignores _EM_DENORMAL)* This is done for portable IEEE behavior on all platforms**Entry:**Exit:**Exceptions:********************************************************************************/
unsigned int _controlfp(unsigned int newctrl, unsigned int mask){ return _control87(newctrl, mask & ~_EM_DENORMAL);}
/***
* _abstract_cw() - abstract control word**Purpose:* produce a fp control word in abstracted (machine independent) form**Entry:* cw: machine control word**Exit:**Exceptions:********************************************************************************/
unsigned int _abstract_cw(unsigned __int64 cw){ unsigned int abstr = 0;
//
// Set exception mask bits
//
if (cw & IEM_INVALID) abstr |= _EM_INVALID; if (cw & IEM_ZERODIVIDE) abstr |= _EM_ZERODIVIDE; if (cw & IEM_OVERFLOW) abstr |= _EM_OVERFLOW; if (cw & IEM_UNDERFLOW) abstr |= _EM_UNDERFLOW; if (cw & IEM_INEXACT) abstr |= _EM_INEXACT; if (cw & IEM_DENORMAL) abstr |= _EM_DENORMAL;
//
// Set rounding mode
//
switch (cw & IMCW_RC) { case IRC_NEAR: abstr |= _RC_NEAR; break; case IRC_UP: abstr |= _RC_UP; break; case IRC_DOWN: abstr |= _RC_DOWN; break; case IRC_CHOP: abstr |= _RC_CHOP; break; }
// Flush to zero mode
if (cw & FTZ) { abstr |= _DN_FLUSH; }
//
// Set Precision mode
//
switch (cw & IMCW_PC) { case IPC_64: abstr |= _PC_64; break; case IPC_53: abstr |= _PC_53; break; case IPC_24: abstr |= _PC_24; break; }
return abstr;}
/***
* _hw_cw() - h/w control word**Purpose:* produce a machine dependent fp control word***Entry:* abstr: abstract control word**Exit:**Exceptions:********************************************************************************/
unsigned __int64 _hw_cw(unsigned int abstr){ //
// Set standard infinity and denormal control bits
//
unsigned __int64 cw = 0;
//
// Set exception mask bits
//
if (abstr & _EM_INVALID) cw |= IEM_INVALID; if (abstr & _EM_ZERODIVIDE) cw |= IEM_ZERODIVIDE; if (abstr & _EM_OVERFLOW) cw |= IEM_OVERFLOW; if (abstr & _EM_UNDERFLOW) cw |= IEM_UNDERFLOW; if (abstr & _EM_INEXACT) cw |= IEM_INEXACT; if (abstr & _EM_DENORMAL) cw |= IEM_DENORMAL;
//
// Set rounding mode
//
switch (abstr & _MCW_RC) { case _RC_NEAR: cw |= IRC_NEAR; break; case _RC_UP: cw |= IRC_UP; break; case _RC_DOWN: cw |= IRC_DOWN; break; case _RC_CHOP: cw |= IRC_CHOP; break; }
// Flush to zero mode
if (abstr & _DN_FLUSH) { cw |= FTZ; }
//
// Set Precision mode
//
switch (abstr & _MCW_PC) { case _PC_64: cw |= IPC_64; break; case _PC_53: cw |= IPC_53; break; case _PC_24: cw |= IPC_24; break; }
return cw;}
/***
* _abstract_sw() - abstract fp status word**Purpose:* produce an abstract (machine independent) fp status word***Entry:* sw: machine status word**Exit:**Exceptions:********************************************************************************/
unsigned int _abstract_sw(unsigned __int64 sw){ unsigned int abstr = 0;
if (sw & ISW_INVALID) abstr |= _SW_INVALID; if (sw & ISW_ZERODIVIDE) abstr |= _SW_ZERODIVIDE; if (sw & ISW_OVERFLOW) abstr |= _SW_OVERFLOW; if (sw & ISW_UNDERFLOW) abstr |= _SW_UNDERFLOW; if (sw & ISW_INEXACT) abstr |= _SW_INEXACT; if (sw & ISW_DENORMAL) abstr |= _SW_DENORMAL;
return abstr;}
/***
* _fpreset() - reset fp system**Purpose:* reset fp environment to the default state* Also reset saved fp environment if invoked from a user's* signal handler**Entry:**Exit:**Exceptions:********************************************************************************/void _fpreset(){ unsigned __int64 status = ICW | 0x9004802700002; /* fpsr.sf1.pc=3, wre=1, traps.dd=1 */ PEXCEPTION_POINTERS excptrs = (PEXCEPTION_POINTERS) _pxcptinfoptrs;
//
// reset fp state
//
_set_fpsr(status);
if (excptrs && excptrs->ContextRecord->ContextFlags & CONTEXT_FLOATING_POINT) { // _fpreset has been invoked by a signal handler which in turn
// has been invoked by the CRT filter routine. In this case
// the saved fp context should be cleared, so that the change take
// effect on continuation.
excptrs->ContextRecord->StFPSR = ICW; }}
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