static unsafe void double_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[1];
int overlap = f.num_taps - 1;
while (num_in > f.dft_length >> 1)
{
int input_offs = p.fifo.offset;
p.fifo.read((f.dft_length - overlap) >> 1, null);
num_in -= (f.dft_length - overlap) >> 1;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by(overlap);
fixed(byte *pinput = &p.fifo.data[input_offs])
fixed(byte *poutput = &output_fifo.data[output_offs])
fixed(double *lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed(int *lsx_fft_br = p.shared.info.lsx_fft_br)
{
double *input = (double *)pinput;
double *output = (double *)poutput;
for (int j = 0, i = 0; i < f.dft_length; ++j, i += 2)
{
output[i] = input[j];
output[i + 1] = 0;
}
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double tmp = output[i];
output[i] = f.coefs[i] * tmp - f.coefs[i + 1] * output[i + 1];
output[i + 1] = f.coefs[i + 1] * tmp + f.coefs[i] * output[i + 1];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
}
}
}
static unsafe void half_sample(stage_t p, fifo_t output_fifo)
{
int num_in = Math.Max(0, p.fifo.occupancy);
dft_filter_t f = p.shared.half_band[p.which];
int overlap = f.num_taps - 1;
while (num_in >= f.dft_length)
{
int input_offs = p.fifo.offset;
p.fifo.read(f.dft_length - overlap, null);
num_in -= f.dft_length - overlap;
int output_offs = output_fifo.reserve(f.dft_length);
output_fifo.trim_by((f.dft_length + overlap) >> 1);
Buffer.BlockCopy(p.fifo.data, input_offs, output_fifo.data, output_offs, f.dft_length * sizeof(double));
fixed(byte *poutput = &output_fifo.data[output_offs])
fixed(double *lsx_fft_sc = p.shared.info.lsx_fft_sc)
fixed(int *lsx_fft_br = p.shared.info.lsx_fft_br)
{
double *output = (double *)poutput;
SOXFft.rdft(f.dft_length, 1, output, lsx_fft_br, lsx_fft_sc);
output[0] *= f.coefs[0];
output[1] *= f.coefs[1];
for (int i = 2; i < f.dft_length; i += 2)
{
double tmp = output[i];
output[i] = f.coefs[i] * tmp - f.coefs[i + 1] * output[i + 1];
output[i + 1] = f.coefs[i + 1] * tmp + f.coefs[i] * output[i + 1];
}
SOXFft.rdft(f.dft_length, -1, output, lsx_fft_br, lsx_fft_sc);
for (int j = 1, i = 2; i < f.dft_length - overlap; ++j, i += 2)
{
output[j] = output[i];
}
}
}
}
