/*** *fpctrl.c - fp low level control and status routines * * Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved. * *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 /*** _statfp *() - * *Purpose: * return user status word * *Entry: * *Exit: * *Exceptions: * *******************************************************************************/ unsigned int _statfp() { short status; _asm { fstsw status } return status; } /*** _clrfp *() - * *Purpose: * return user status word and clear status * *Entry: * *Exit: * *Exceptions: * *******************************************************************************/ unsigned int _clrfp() { short status; _asm { fnstsw status fnclex } return status; } /*** _ctrlfp *() - * *Purpose: * return and set user control word * *Entry: * *Exit: * *Exceptions: * *******************************************************************************/ unsigned int _ctrlfp(unsigned int newctrl, unsigned int _mask) { short oldCw; short newCw; _asm { fstcw oldCw } newCw = (short) ((newctrl & _mask) | (oldCw & ~_mask)); _asm { fldcw newCw } return oldCw; } /*** _set_statfp *() - * *Purpose: * force selected exception flags to 1 * *Entry: * *Exit: * *Exceptions: * *******************************************************************************/ static unsigned long over[3] = { 0x0, 0x80000000, 0x4410 }; static unsigned long under[3] = { 0x1, 0x80000000, 0x3000 }; void _set_statfp(unsigned int sw) { int itmp; double tmp; if (sw & ISW_INVALID) { _asm { fld tbyte ptr over fistp itmp fwait } } if (sw & ISW_OVERFLOW) { // will also trigger precision _asm { fstsw ax fld tbyte ptr over fstp tmp fwait fstsw ax } } if (sw & ISW_UNDERFLOW) { // will also trigger precision _asm { fld tbyte ptr under fstp tmp fwait } } if (sw & ISW_ZERODIVIDE) { _asm { fldz fld1 fdivrp st(1), st fstp st(0) fwait } } if (sw & ISW_INEXACT) { _asm { fldpi fstp tmp fwait } } }