@@ -39,6 +39,10 @@ All DSP units share a common architecture depicted by the following figure. They

### Currently available DSP units

#### LDPC, a Low Density Parity Check code decoder

LDPC implements all LDPC codes of 802.11n. Starting from an input frame of 8 bits soft Log Likelyhood Ratios (LLR) it iterates a programmable number of times and delivers a frame of posterior LLRs that can be sliced to produce a decoded codeword. The decoding algorithm is the Self-Corrected MinSum.

#### INTL, a general purpose interleaver

INTL takes a set of input samples and a permutation table and outputs a permuted set of samples. The bit width of the samples can be anything between one and eight bits. INTL is also useful for rate matching and frame equalization, thanks to several special features like force-zero-sample, force-one-sample, skip-sample, repeat-sample, etc. When de-interleaving, if some input samples were repeated by the transmitter, INTL can replace the set of repeated samples by their average value or by the last occurrence. The largest applicable permutation is 32768 samples but larger permutations can be obtained in multiple passes (a 65536-samples permutation, for instance, requires four 32768-samples passes).