const float4 ePi = float4(
        3.14159e-00,
        2.65358e-06,
        9.79323e-12,
        8.46264e-18
);


#ifndef PI_PRECISION
#define PI_PRECISION 0
#endif

#if PI_PRECISION == 0
const float cPi = 3.14159265; // 3.14159274
const float getPi() {
    return cPi;
}

#elif PI_PRECISION == -1
const float getPi() {
    float xPi : register( r2 );
    asm {
        ps_3_0
        
    }
}
#elif PI_PRECISION == 24 
const float getPi() {
    float rPi;
    rPi = ePi[3] +
          ePi[2] +
          ePi[1] +
          ePi[0] ;
    return rPi;
}
#elif PI_PRECISION == 18 
const float getPi() {
    float rPi;
    rPi = ePi[2] +
          ePi[1] +
          ePi[0] ;
    return rPi;
}
#elif PI_PRECISION == 12
const float getPi() {
    volatile float rPi;
    rPi = ePi[1] +
          ePi[0] ;
    return rPi;
}
#endif
 
float4 main( float4 unk1 : COLOR1, float4 unk2 : COLOR2 ) : COLOR0 {
    // arguments to main are 'uncertain', and so are not const-expression optimized away
    float Pi = getPi();
    return float4( Pi, Pi, Pi, Pi );
}