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Synopsis:
    #include <float.h>
    unsigned int _control87( unsigned int newcw,
                             unsigned int mask );

Description:
    The _control87 function updates the control word of the
    8087/80287/80387/80486.  If mask is zero, then the control word is not
    updated.  If mask is non-zero, then the control word is updated with
    bits from newcw corresponding to every bit that is on in mask.

Returns:
    The _control87 function returns the new control word.  The description
    of bits defined for the control word is found in the <float.h> header
    file.

See Also:
    _clear87, _fpreset, _status87

Example:
    #include <stdio.h>
    #include <float.h>

    char *status[2] = { "disabled", "enabled" };

    void main()
      {
        unsigned int fp_cw = 0;
        unsigned int fp_mask = 0;
        unsigned int bits;

        fp_cw = _control87( fp_cw,
                            fp_mask );

        printf( "Interrupt Exception Masks\n" );
        bits = fp_cw & MCW_EM;
        printf( "  Invalid Operation exception %s\n",
                status[ (bits & EM_INVALID) == 0 ] );
        printf( "  Denormalized exception %s\n",
                status[ (bits & EM_DENORMAL) == 0 ] );
        printf( "  Divide-By-Zero exception %s\n",
                status[ (bits & EM_ZERODIVIDE) == 0 ] );
        printf( "  Overflow exception %s\n",
                status[ (bits & EM_OVERFLOW) == 0 ] );
        printf( "  Underflow exception %s\n",
                status[ (bits & EM_UNDERFLOW) == 0 ] );
        printf( "  Precision exception %s\n",
                status[ (bits & EM_PRECISION) == 0 ] );

        printf( "Infinity Control = " );
        bits = fp_cw & MCW_IC;
        if( bits == IC_AFFINE )     printf( "affine\n" );
        if( bits == IC_PROJECTIVE ) printf( "projective\n" );

        printf( "Rounding Control = " );
        bits = fp_cw & MCW_RC;
        if( bits == RC_NEAR )       printf( "near\n" );
        if( bits == RC_DOWN )       printf( "down\n" );
        if( bits == RC_UP )         printf( "up\n" );
        if( bits == RC_CHOP )       printf( "chop\n" );

        printf( "Precision Control = " );
        bits = fp_cw & MCW_PC;
        if( bits == PC_24 )         printf( "24 bits\n" );
        if( bits == PC_53 )         printf( "53 bits\n" );
        if( bits == PC_64 )         printf( "64 bits\n" );
      }

Classification:
    Intel

Systems:
    All