internal static void fDCT2D_llm(
MutableSpan <float> s,
MutableSpan <float> d,
MutableSpan <float> temp,
bool downscaleBy8 = false,
bool offsetSourceByNeg128 = false)
{
MutableSpan <float> sWorker = offsetSourceByNeg128 ? s.AddScalarToAllValues(-128f) : s;
for (int j = 0; j < 8; j++)
{
fDCT1Dllm_32f(sWorker.Slice(j * 8), temp.Slice(j * 8));
}
Transpose8x8(temp, d);
for (int j = 0; j < 8; j++)
{
fDCT1Dllm_32f(d.Slice(j * 8), temp.Slice(j * 8));
}
Transpose8x8(temp, d);
if (downscaleBy8)
{
for (int j = 0; j < 64; j++)
{
d[j] *= 0.125f;
}
}
}
public void IntegerDCT_ForwardThenInverse(int seed, int startAt)
{
MutableSpan <int> original = Create8x8RandomIntData(-200, 200, seed);
var block = original.AddScalarToAllValues(128);
ReferenceImplementations.IntegerReferenceDCT.TransformFDCTInplace(block);
for (int i = 0; i < 64; i++)
{
block[i] /= 8;
}
ReferenceImplementations.IntegerReferenceDCT.TransformIDCTInplace(block);
for (int i = startAt; i < 64; i++)
{
float expected = original[i];
float actual = (float)block[i];
Assert.Equal(expected, actual, new ApproximateFloatComparer(3f));
}
}