FA-81372 / MIDI event timing / Member archive

Variable-length quantity stream decoder: previous quantity bleeds into the next · case 02

In [0, 129, 0, 5] the second and third values absorb earlier bits instead of reading 128 and 5.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Input a list of byte values. Decode consecutive variable-length quantities (7 data bits per byte, bit 7 = continuation, most significant first, at most 4 bytes each). Return the list of values; return None for a byte outside 0..255, a quantity whose fourth byte still has the continuation bit, or a truncated final quantity.

Why this case matters

MIDI sequencers, file readers and synth drivers depend on exact event ordering and tick/time arithmetic.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
oracle 4	`[128, 16384, 268435584]`	`[128, 0, 128]`	Failed

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