f16spec.cpp

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// $Id: f16spec.cpp 1282 2006-06-09 09:46:49Z alex $
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               Xara LX, a vector drawing and manipulation program.
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 */

// fixed16 code that will probably need changing between platforms
// (portable code can be found in fixed16.cpp). This is the Windows version



#include "camtypes.h"
#include "f16spec.h"
//#include "source.h"
#include <math.h>
//#include "errors.h" - in camtypes.h [AUTOMATICALLY REMOVED]
//#include "andy.h"

DECLARE_SOURCE("$Revision: 1282 $");

#define TORADIANS(x)    ((x)/180.0*PI)

/********************************************************************************************

>   BOOL MathCoprocInstalled;

    Author:     Mario_Shamtani (Xara Group Ltd) <camelotdev@xara.com>
    Created:    11/6/93
    SeeAlso:    InitMaths() 
    Purpose:    
        Flag used to determine if there is a maths coprocessor present. Its default setting 
        is FALSE i.e. there is no coprocessor installed. This is mainly used to hint GDraw
        how to do things most efficiently.
    
    Errors:     None.

********************************************************************************************/

static BOOL MathCoprocInstalled = FALSE;

// set this to 1 for the test. Disabled because we have yet to get a Pentium to try it on
#define PENTIUM_TEST    0


#if PENTIUM_TEST
// Pentium FDIV bug test code
//
// Here is a simple test  that will reproduce the bug, if present;
// if this gives "256.000000" as result, your system is affected; on a 486,
// this gives "0.000000". The fn returns true if the FPU is OK

// (Note we have never seen this check go off as we have no Pentium machines)

static volatile double IFPBFFOd0=0;

static volatile double * IsFloatingPointBugFreeFoolOptimiser(volatile double * pdbl)
{
    if (pdbl) pdbl++;
    IFPBFFOd0 = *(--pdbl);
    return (pdbl); // This function just returns its own value.
}

// (This code obtained by Alex from somewhere on the net)

static BOOL IsFloatingPointBugFree()
{
    volatile double *w,*x,*y,*z;

    volatile double wd,xd,yd,zd;

    w=&wd;
    x=&xd;
    y=&yd;
    z=&zd;

    w=IsFloatingPointBugFreeFoolOptimiser(w);
    x=IsFloatingPointBugFreeFoolOptimiser(x);
    y=IsFloatingPointBugFreeFoolOptimiser(y);
    z=IsFloatingPointBugFreeFoolOptimiser(z);

    (*x) = 4195835.0;
    (*y) = 3145727.0;
    (*z) = ((*x)/(*y));

    w=IsFloatingPointBugFreeFoolOptimiser(w);
    x=IsFloatingPointBugFreeFoolOptimiser(x);
    y=IsFloatingPointBugFreeFoolOptimiser(y);
    z=IsFloatingPointBugFreeFoolOptimiser(z);

    (*z) = (*z) * (*y);

    w=IsFloatingPointBugFreeFoolOptimiser(w);
    x=IsFloatingPointBugFreeFoolOptimiser(x);
    y=IsFloatingPointBugFreeFoolOptimiser(y);
    z=IsFloatingPointBugFreeFoolOptimiser(z);

    (*w) = (*x) - (*z);

    w=IsFloatingPointBugFreeFoolOptimiser(w);
    x=IsFloatingPointBugFreeFoolOptimiser(x);
    y=IsFloatingPointBugFreeFoolOptimiser(y);
    z=IsFloatingPointBugFreeFoolOptimiser(z);

    return ((*w)<128.0);
}
#endif      // PENTIUM_TEST


/********************************************************************************************

>   BOOL IsMathCoprocInstalled()

    Author:     Andy_Pennell (Xara Group Ltd) <camelotdev@xara.com>
    Created:    19/1/95
    Returns:    TRUE if the hardware supports a real FPU, FALSE if emulated.
    Purpose:    Gives a hint to those that need to know things about FPU performance.
    Errors:     None.

********************************************************************************************/

BOOL IsMathCoprocInstalled()
{
#if defined(__WXMSW__)
    // the theoretically proper way to detect an FPU is to delve into the reigstry thus:
    // NT  entry lives at HKEY_LOCAL_MACHINE\HARDWARE\DESCRIPTION\System\FloatingPointProcessor\0
    // W95 entry lives at HKEY_LOCAL_MACHINE\Enum\Root\*PNP0C01\0000NDP (M7 liable to change)
    // W32s is only available by thunking to WinFlags() (ug).
    // Instead, we use a tiny bit of .asm, as suggested by Mr-Asm himself, Gavin

    WORD RegCR0;
    _asm
    {
        smsw    RegCR0                  // bit 2 of CR0 is the EM bit, set for emulation
    }

    return (RegCR0 & 4) ? FALSE : TRUE;
#else
    return TRUE;
#endif
}

/********************************************************************************************

>   BOOL InitMaths()

    Author:     Mario_Shamtani (Xara Group Ltd) <camelotdev@xara.com>
    Created:    26/4/93
    Inputs:     None.
    Outputs:    None
    Returns:    A Boolean if initialisation was ok.
    Purpose:    Initialises the maths class. Windows version tests for maths coprocessor.
                Also sets up maths exception vectors.
    Errors:     None.

********************************************************************************************/

BOOL InitMaths()
{

    MathCoprocInstalled = IsMathCoprocInstalled();

    #if PENTIUM_TEST
    // now check for faulty Pentium
    if ( !IsFloatingPointBugFree() )
    {
        Error::SetError( _R(IDE_BAD_PENTIUM) );
        InformError();
    }
    #endif

    return TRUE;
}          


/********************************************************************************************

>   FIXED16& FIXED16::Sin() 

    Author:     Mario_Shamtani (Xara Group Ltd) <camelotdev@xara.com>
    Created:    14/5/93
    SeeAlso:    Fixed16Sin() 
    Inputs:     None.
    Outputs:    None
    Returns:    A reference to an FIXED16 with result of sin. Input argument must be in
                DEGREES not radians.
    Purpose:    Performs sine on a FIXED16.
    Errors:     None.

********************************************************************************************/

fixed16& fixed16::Sin() 
{
#ifndef WIN32
    if (MathCoprocInstalled)                    //Is MathCoprocessor installed
        *this = Fixed16Sin(*this);
    else
#endif
        *this = sin(TORADIANS(this->MakeDouble()));

ERROR3("Alex doubts whether this routine works");

    return *this;
}

/********************************************************************************************

>   FIXED16& FIXED16::Cos() 

    Author:     Mario_Shamtani (Xara Group Ltd) <camelotdev@xara.com>
    Created:    14/5/93
    SeeAlso:    Fixed16Cos()
    Inputs:     None.
    Outputs:    None
    Returns:    A reference to an FIXED16 with result of Cos. Input argument must be in
                DEGREES not radians.
    Purpose:    Performs Cos on a FIXED16.
    Errors:     None.

********************************************************************************************/

fixed16& fixed16::Cos() 
{
#ifndef WIN32
    if (MathCoprocInstalled)                //Is MathCoprocessor installed
        *this = Fixed16Cos(*this);
    else
#endif
        *this = cos(TORADIANS(this->MakeDouble()));

ERROR3("Alex doubts whether this routine works");

    return *this;
}

---