public static void Logarithm(ReadOnlySpan <double> src, double srcMinFrequency, double srcMaxFrequency, Span <double> dst, ILogarithm log)
{
src.Handle(dst, (ReadOnlySpan <double> @in, Span <double> @out) => {
var srcWidth = @in.Length;
var dstWidth = @out.Length;
if (log != null)
{
var logChanged = logarithmCache.Log != log;
if (logChanged)
{
logarithmCache.Log = log;
}
if (logChanged || logarithmCache.MinFrequency != srcMinFrequency || logarithmCache.MaxFrequency != srcMaxFrequency)
{
logarithmCache.MinFrequency = srcMinFrequency;
logarithmCache.MaxFrequency = srcMaxFrequency;
logarithmCache.MinFrequencyLog = log.Log(srcMinFrequency);
logarithmCache.MaxFrequencyLog = log.Log(srcMaxFrequency);
}
if (logChanged || logarithmCache.Width != dstWidth)
{
double scale = (srcWidth - 1) / (srcMaxFrequency - srcMinFrequency);
double minMel = logarithmCache.MinFrequencyLog;
double maxMel = logarithmCache.MaxFrequencyLog;
double mscale = (maxMel - minMel) / dstWidth;
var cache = new double[dstWidth + 1];
for (int i = 0; i <= dstWidth; i++)
{
cache[i] = (log.ILog(i * mscale + minMel) - srcMinFrequency) * scale;
}
logarithmCache.Width = dstWidth;
logarithmCache.Data = cache;
}
fixed(double *cache = logarithmCache.Data)
{
for (int i = 0; i < dstWidth; i++)
{
@out[i] = Max(@in, cache[i], cache[i + 1]);
}
}
}
else
{
double scale = (double)(srcWidth - 1) / dstWidth;
for (int i = 0; i < dstWidth; i++)
{
double x1 = i * scale;
double x2 = x1 + scale;
@out[i] = Max(@in, x1, x2);
}
}
});
}
public static void Logarithm(double *src, int srcWidth, double srcMinFrequency, double srcMaxFrequency, double *dst, int dstWidth, ILogarithm log)
{
if (log != null)
{
double scale = (srcWidth - 1) / (srcMaxFrequency - srcMinFrequency);
double minMel = log.Log(srcMinFrequency);
double maxMel = log.Log(srcMaxFrequency);
double mscale = (maxMel - minMel) / dstWidth;
for (int i = 0; i < dstWidth; i++)
{
double x1 = (log.ILog(i * mscale + minMel) - srcMinFrequency) * scale;
double x2 = (log.ILog((i + 1) * mscale + minMel) - srcMinFrequency) * scale;
dst[i] = Max(src, srcWidth, x1, x2);
}
}
else
{
double scale = (double)(srcWidth - 1) / dstWidth;
for (int i = 0; i < dstWidth; i++)
{
double x1 = i * scale;
double x2 = x1 + scale;
dst[i] = Max(src, srcWidth, x1, x2);
}
}
}
