FA-89083 / Digital logic simulation / Member archive

Falling edges into unknown are missed · case 03

1->x and 1->z transitions are not reported as negedges.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

Input [seq]: a string of samples over '0','1','x','z'. Levels order 0 < {x,z} < 1 (x and z are the same middle level). A change to a higher level is a posedge (0->1, 0->x, 0->z, x->1, z->1), to a lower level a negedge; x<->z is no edge. The first sample has no predecessor. Return [posedge indices, negedge indices].

Why this case matters

Event controls on clocks and resets fire on unknown transitions; an edge classifier that only knows 0->1 misses or invents triggers.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
edges through unknown and floating	`[[1, 2], [4]]`	`[[1, 2], [3, 4]]`	Failed

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