25 Oktober 2011 9:28
I'm trying to implement reduced clock operation and trying to understand fetchdt.h.
I have some questions
1. in body of FetchDMADataTouchDownSampled44, there is already "downsample from 40MHz to 20MHz" (below code)
Is it already implement half-clock operation? If not, what is purpose of this part?
// Downsample from 40MHz to 20MHz
// Mem2VcsL and Mem2VcsH work together to downsample sequential 2 signal block into one signal block
Mem2VcsL(*(SignalBlock*)p40MStream , block, block, block, block); // vcs is 4 complex16 samples
Mem2VcsH(*((SignalBlock*)p40MStream + 1), block, block, block, block);
return hr; // return S_OK if succed
2. in body of resampler.resample ( in 44Mto40M.h ), it use LinearTableR, LinearTableL for downsampling 44M to 40M.
What is mean of LinearTableR(and L)? What's mean of value of element in LinearTableR?
I want to implement half-clock operation, than should I change this LinearTableR?
3. in Mem2VcsH fuctio, what is mean of m128FirstHalfMask and ~0 which is an element in m128FirstHalfMask? (in fetchdt.h)