FA-71915 / Error-correcting codes / Member archive

Deinterleaver splits the stream by row length · case 05

Non-square interleavers put flags in the wrong codewords.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

A rows x cols block interleaver writes codewords row by row (each row is one codeword of cols symbols) and transmits column by column. Given per-symbol error flags in transmission order, deinterleave them back to row order, find the largest number of flagged symbols in any codeword, and report whether it is within the per-codeword capability t. Return [deinterleaved flags, worst, correctable]; mismatched sizes return None.

Why this case matters

Interleaving spreads channel bursts across codewords; link budgets check whether a burst stays correctable.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression [[0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0], 6, 2, 1]	`[[0, 0, 0, 0, 0, 0, 0, 0, null, null, null, null], 0, true]`	`[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0], 1, true]`	Failed

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