One polyphase branch of a block 2x stage: a direct-form FIR whose every output is the taps summed oldest-first, one multiply-add each (fused where the hardware has it; see fir_multiply_add()).
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template<typename SampleType>
class pulp::signal::detail::FixedOrderFirBranch< SampleType >
One polyphase branch of a block 2x stage: a direct-form FIR whose every output is the taps summed oldest-first, one multiply-add each (fused where the hardware has it; see fir_multiply_add()).
That fixed per-output order is the point. A vectorised correlation (vDSP_conv, a tree-reduced dot) regroups the sum differently depending on how many outputs one call produces, so the same signal fed in different block sizes rounds differently. Here sixteen outputs advance together in registers and a ragged tail runs the identical sequence one output at a time, so the result is bit-identical for any partition of the input — including one sample at a time.
1.15.0