src/shared/cmake/CheckFloatByte.cpp.in

  typedef long double float_t;
  typedef long int32_t;
  typedef char uint8_t;
  
  //float to bits conversion utilities...
  union clvalue {
	 int32_t     i;
	 float		f; //must use a float type, else types dont match up
  };
  
  int32_t floatToIntBits(float_t value)
  {
	 clvalue u;
	 int32_t e, f;
	 u.f = value;
	 e = u.i & 0x7f800000;
	 f = u.i & 0x007fffff;

	 if (e == 0x7f800000 && f != 0)
	 u.i = 0x7fc00000;
		
	 return u.i;
  }
  float_t intBitsToFloat(int32_t bits)
  {
	 clvalue u;
	 u.i = bits;
	 return u.f;
  }
  
  float_t byteToFloat(uint8_t b) {
	 if (b == 0)                                   // zero is a special case
		  return 0.0f;
	 int32_t mantissa = b & 7;
	 int32_t exponent = (b >> 3) & 31;
	 int32_t bits = ((exponent+(63-15)) << 24) | (mantissa << 21);
	 return intBitsToFloat(bits);
  }

  uint8_t floatToByte(float_t f) {
	 if (f < 0.0f)                                 // round negatives up to zero
		  f = 0.0f;

	 if (f == 0.0f)                                // zero is a special case
		  return 0;

	 int32_t bits = floatToIntBits(f);           // parse float_t into parts
	 int32_t mantissa = (bits & 0xffffff) >> 21;
	 int32_t exponent = (((bits >> 24) & 0x7f) - 63) + 15;

	 if (exponent > 31) {                          // overflow: use max value
		  exponent = 31;
		  mantissa = 7;
	 }

	 if (exponent < 0) {                           // underflow: use min value
		  exponent = 0;
		  mantissa = 1;
	 }

	 return (uint8_t)((exponent << 3) | mantissa);    // pack into a uint8_t
  }
  

#ifdef __CLASSIC_C__
int main(){
  int ac;
  char*av[];
#else
int main(int ac, char*av[]){
#endif
  //well known conversion
  if ( floatToByte(0.5f) != 120 )
		return 1;
  
  //converting back works?
  if ( floatToByte(byteToFloat(57)) != 57 )
		return 1;

  return 0;
}