FA-72107 / Error-correcting codes / Member archive

Bit flipping stops before checking the last flip · case 02

Words fixed by the final permitted iteration are reported as failures.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Parallel Gallager bit-flipping decoder. H lists the variable indices of each parity check. In each iteration: if every check is satisfied stop with success; otherwise count, per bit, the unsatisfied checks it joins and flip all bits that reach the maximum count. At most max_iter flipping iterations are performed and the syndrome is checked after the last one. Return [bits, iterations performed, success].

Why this case matters

Hard-decision LDPC decoders in flash controllers use bit flipping as a low-power first pass.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression [[[0, 1, 3], [1, 2, 4], [0, 2, 5], [3, 4, 5]], [0, 0, 0, 1, 0, 0], 1]	`[[0, 0, 0, 0, 0, 0], 1, false]`	`[[0, 0, 0, 0, 0, 0], 1, true]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.