windows-xp/Source/XPSP1/NT/base/wow64/mscpu/math/modf.c

/*++
                                                                                
Copyright (c) 1999 Microsoft Corporation

Module Name:

   modf.c 

Abstract:
    
   modf()  function
    
Author:



Revision History:

    29-sept-1999 ATM Shafiqul Khalid [askhalid] copied from rtl library.
--*/

#include <math.h>
#include <trans.h>
#include <float.h> 

extern double _frnd(double);
extern double _copysign (double x, double y);

/***
*double modf(double x, double *intptr)
*
*Purpose:
*   Split x into fractional and integer part
*   The signed fractional portion is returned
*   The integer portion is stored as a floating point value at intptr
*
*Entry:
*
*Exit:
*
*Exceptions:
*    I
*******************************************************************************/
static  unsigned int newcw = (ICW & ~IMCW_RC) | (IRC_CHOP & IMCW_RC);

double modf(double x, double *intptr)
{
    unsigned int savedcw;
    double result,intpart;

    /* save user fp control word */
    savedcw = _ctrlfp(0, 0);     /* get old control word */
    _ctrlfp(newcw,IMCW);    /* round towards 0 */

    /* check for infinity or NAN */
    if (IS_D_SPECIAL(x)){
    *intptr = QNAN_MODF;
    switch (_sptype(x)) {
    case T_PINF:
    case T_NINF:
        *intptr = x;
        result = _copysign(0, x);
        RETURN(savedcw,result);
    case T_QNAN:
        *intptr = x;
        return _handle_qnan1(OP_MODF, x, savedcw);
    default: //T_SNAN
        result = _s2qnan(x);
        *intptr = result;
        return _except1(FP_I, OP_MODF, x, result, savedcw);
    }
    }

    if (x == 0.0) {
    *intptr = x;
    result = x;
    }

    else {
    intpart = _frnd(x); //fix needed: this may set the P exception flag
            //and pollute the fp status word

    *intptr = intpart;
    result = x - intpart;
    }

    RETURN(savedcw,result);
}