Leaked source code of windows server 2003
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118 lines
2.1 KiB

/***
*fpctrl.c - fp low level control and status routines
*
* Copyright (c) 1985-2000, Microsoft Corporation
*
*Purpose:
* IEEE control and status routines for internal use.
* These routines use machine specific constants while _controlfp,
* _statusfp, and _clearfp use an abstracted control/status word
*
*Revision History:
*
* 03-31-92 GDP written
* 05-12-92 GJF Rewrote fdivr as fdivrp st(1),st to work around C8-32
* assertions.
*
*/
#include <trans.h>
extern unsigned int _get_fpsr(void);
extern void _set_fpsr(unsigned int);
extern void _fclrf(void);
/*** _statfp
*() -
*
*Purpose:
* return user status word
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
uintptr_t _statfp()
{
unsigned int status;
status = _get_fpsr() & ISW;
return (uintptr_t)status;
}
/*** _clrfp
*() -
*
*Purpose:
* return user status word and clear status
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
uintptr_t _clrfp()
{
unsigned int status;
status = _get_fpsr() & ISW;
_fclrf();
return (uintptr_t)status;
}
/*** _ctrlfp
*() -
*
*Purpose:
* return and set user control word
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
uintptr_t _ctrlfp(uintptr_t newctrl, uintptr_t _mask)
{
unsigned int oldCw;
unsigned int newCw;
unsigned int tmp;
oldCw = _get_fpsr();
newCw = ((unsigned int)(newctrl & _mask) | (oldCw & (unsigned int)~_mask));
_set_fpsr(newCw);
return (uintptr_t)oldCw;
}
/*** _set_statfp
*() -
*
*Purpose:
* force selected exception flags to 1
*
*Entry:
*
*Exit:
*
*Exceptions:
*
*******************************************************************************/
void _set_statfp(uintptr_t sw)
{
unsigned int status;
status = _get_fpsr() | ((unsigned int)sw & ISW);
_set_fpsr(status);
}