public void NegativeInfinite()
{
var result = new ieee754_Float32(float.NegativeInfinity);
Assert.That(result.IsNegative, Is.EqualTo(true));
Assert.That(result.Exponent, Is.EqualTo(ieee754_Float32.EXPONENT_RESERVED));
Assert.That(result.Mantissa, Is.EqualTo(0));
Assert.That(result.Value, Is.EqualTo(float.NegativeInfinity));
}
public void Zero()
{
var result = new ieee754_Float32(0f);
Assert.That(result.IsNegative, Is.EqualTo(false));
Assert.That(result.Exponent, Is.EqualTo(ieee754_Float32.EXPONENT_MIN));
Assert.That(result.Mantissa, Is.EqualTo(0));
Assert.That(result.Value, Is.EqualTo(0f));
}
public void MinusOne()
{
var result = new ieee754_Float32(-1f);
Assert.That(result.IsNegative, Is.EqualTo(true));
Assert.That(result.Exponent, Is.EqualTo(0));
Assert.That(result.Mantissa, Is.EqualTo(0));
Assert.That(result.Value, Is.EqualTo(-1f));
}
public static float ConvertToFloat32(int fixedValue, int floatBitCount)
{
var isNegative = fixedValue < 0;
if (isNegative)
{
fixedValue = -fixedValue;
}
var index = FindFirstActiveBitIndex((uint)fixedValue);
var exponent = fixedValue == 0 ? -ieee754_Float32.EXPONENT_BIAS : index - floatBitCount - 1;
var fraction = ieee754_Float32.MANTISSA_BIT_COUNT - index + 1;
var mantissa = fraction < 0 ? fixedValue >> -fraction : fixedValue << fraction;
var floatValue = new ieee754_Float32(isNegative, exponent, mantissa);
return(floatValue.Value);
}
public static int ConvertToFixed(float value, int floatBitCount)
{
var ieee_float = new ieee754_Float32(value);
if (ieee_float.IsZero)
{
return(0);
}
if (ieee_float.IsReserved)
{
throw new System.ArgumentException("NaN or Infinity can NOT convert to Fixed32.");
}
var fixedResult = ieee_float.Mantissa | 1 << ieee754_Float32.MANTISSA_BIT_COUNT;
// 실수 비트 수
var fraction = ieee754_Float32.MANTISSA_BIT_COUNT - ieee_float.Exponent;
// 만약 실수 비트수가 결과값의 비트수를 넘어가면,
if (fraction > 32)
{
// 오프셋만큼 가수부를 밀어주고, 실수 비트는 결과값 비트수로 변경한다.
var offset = fraction - 32;
fixedResult >>= offset;
fraction = 32;
}
// 지정한 실수 비트 수와의 차이만큼 교정해준다.
var offsetFloatBitCount = fraction - floatBitCount;
fixedResult >>= offsetFloatBitCount;
// 음수면, 2의 보수로 음수화 한다.
if (ieee_float.IsNegative)
{
fixedResult = ~fixedResult + 1;
}
return(fixedResult);
}
