public IEnumerable<float> Enumerate(FloatDescription desc)
{
var max = Math.Pow(2, desc.BitCount);
for (var i = 0; i < max; i++) {
var bcount = desc.BitCount / 8;
if (desc.BitCount % 8 != 0) {
bcount += 1;
}
var bytes = BitConverter.GetBytes(i).Take(bcount).Reverse().ToArray();
var value = FromBytes(desc, bytes);
yield return value;
}
}
public float FromBytes(FloatDescription desc, params byte[] bytes)
{
var remainder = desc.BitCount % 8;
var byteCount = desc.BitCount / 8;
if (remainder > 0) {
byteCount += 1;
}
if (bytes.Length > byteCount) throw new Exception("too many bytes");
var newBytes = bytes.Take(byteCount).ToArray();
var bits = newBytes.SelectMany(ByteToBits).Take(desc.BitCount).ToArray();
var floatParts = ToFloatParts(desc, bits);
var value = FromFloatParts(desc, floatParts);
return value;
}
public float FromFloatParts(FloatDescription desc, FloatParts parts)
{
var isZero = true;
var sign = parts.Sign > 0 ? -1 : 1;
var e = BitsToInt(parts.Exponent) - desc.ExponentBias;
if (e != 0) {
isZero = false;
}
var exp = Math.Pow(2.0, e);
double frac = 0;
frac += 1;
for (var i = 0; i < desc.SignificandBits; i++) {
if (parts.Fraction[i] == Bit.One) {
frac += Math.Pow(2.0, -(i + 1));
isZero = false;
}
}
if (isZero) {
return 0;
}
return (float)(sign * frac * exp);
}
public FloatParts ToFloatParts(FloatDescription desc, Bit[] bits)
{
if (bits.Length != desc.BitCount) {
throw new Exception("not enough bits");
}
var e = new List<Bit>();
var f = new List<Bit>();
if (desc.ExponentBits > 0) {
e = bits.Skip(1).Take(desc.ExponentBits).ToList();
}
if (desc.SignificandBits > 0) {
f = bits.Skip(1 + desc.ExponentBits).ToList();
}
var parts = new FloatParts {
Sign = bits[0],
Exponent = e.ToArray(),
Fraction = f.ToArray()
};
return parts;
}
