FA-88946 / Digital logic simulation / Open access

Data change at the clock edge escapes both checks · case 01

A data transition exactly at the rising edge is not reported at all.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The hold window is opened at the edge, and the setup window is also open there, leaving a gap.

VERIFIED REPAIR

Start the hold window at the edge instant: e <= t < e + hold.

Unsuccessful approach: Shifting the window to (e, e+hold] still misses the edge instant and wrongly flags e+hold.

Case contract

Input [c0, clock, data, setup, hold]: c0 is the initial clock level, clock is time-sorted [t, v] transitions (possibly redundant), data is a list of data transition times. Rising edges are 0->1 changes only. For every data time t and every rising edge e: e-setup < t < e is a 'setup' violation, e <= t < e+hold is a 'hold' violation. Return all [e, t, kind] sorted by edge, then time.

Why this case matters

Timing checks in gate-level simulation decide which transitions corrupt a register; window boundaries and edge extraction are the classic bug sites.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(*args):
    c0, clock, data, s, h = args
    edges = []
    prev = c0
    for t, v in clock:
        if prev == 0 and v == 1:
            edges.append(t)
        prev = v
    out = []
    for t in data:
        for e in edges:
            if e - s < t < e:
                out.append([e, t, 'setup'])
            elif e < t < e + h:
                out.append([e, t, 'hold'])
    return sorted(out)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [21, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [13, 1]], [3, 5, 11], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [22, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [14, 1]], [3, 5, 12], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 17, 27], 3, 2], [[10, 8, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [23, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [15, 1]], [3, 5, 13], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [24, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [16, 1]], [3, 5, 14], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [25, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [17, 1]], [3, 5, 15], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
setup window boundaries	`[[10, 8, 'setup'], [20, 18, 'setup']]`	`[[10, 8, 'setup'], [20, 18, 'setup']]`	Passed
transition exactly at the clock edge	`[[30, 29, 'setup']]`	`[[20, 20, 'hold'], [30, 29, 'setup']]`	Failed
falling clock edges are not checked	`[]`	`[]`	Passed
redundant high transition is not an edge	`[]`	`[]`	Passed
clock already high at start	`[]`	`[]`	Passed
clock low at start rises first	`[[4, 3, 'setup']]`	`[[4, 3, 'setup']]`	Passed
overlapping windows reported by edge	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup']]`	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']]`	Failed

SHA-256 / c51fd16b0cb023d4dc940802d6b2d73472c1407a61b1395a5ffbb22467885f14

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(*args):
    c0, clock, data, s, h = args
    edges = []
    prev = c0
    for t, v in clock:
        if prev == 0 and v == 1:
            edges.append(t)
        prev = v
    out = []
    for t in data:
        for e in edges:
            if e - s < t < e:
                out.append([e, t, 'setup'])
            elif e < t <= e + h:
                out.append([e, t, 'hold'])
    return sorted(out)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [21, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [13, 1]], [3, 5, 11], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [22, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [14, 1]], [3, 5, 12], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 17, 27], 3, 2], [[10, 8, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [23, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [15, 1]], [3, 5, 13], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [24, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [16, 1]], [3, 5, 14], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [25, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [17, 1]], [3, 5, 15], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
setup window boundaries	`[[10, 8, 'setup'], [20, 18, 'setup']]`	`[[10, 8, 'setup'], [20, 18, 'setup']]`	Passed
transition exactly at the clock edge	`[[20, 22, 'hold'], [30, 29, 'setup']]`	`[[20, 20, 'hold'], [30, 29, 'setup']]`	Failed
falling clock edges are not checked	`[]`	`[]`	Passed
redundant high transition is not an edge	`[]`	`[]`	Passed
clock already high at start	`[]`	`[]`	Passed
clock low at start rises first	`[[4, 3, 'setup'], [4, 6, 'hold']]`	`[[4, 3, 'setup']]`	Failed
overlapping windows reported by edge	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup']]`	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']]`	Failed

SHA-256 / ccd486435f026cd5a2d27600cdc3e530423c5a4f83ace9b153b454b8dd22ec48

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(*args):
    c0, clock, data, s, h = args
    edges = []
    prev = c0
    for t, v in clock:
        if prev == 0 and v == 1:
            edges.append(t)
        prev = v
    out = []
    for t in data:
        for e in edges:
            if e - s < t < e:
                out.append([e, t, 'setup'])
            elif e <= t < e + h:
                out.append([e, t, 'hold'])
    return sorted(out)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [21, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [13, 1]], [3, 5, 11], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [22, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [14, 1]], [3, 5, 12], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 17, 27], 3, 2], [[10, 8, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [23, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [15, 1]], [3, 5, 13], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 18, 27], 3, 2], [[10, 8, 'setup'], [20, 18, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 30], 3, 2], [[20, 20, 'hold'], [30, 30, 'hold']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 26], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [24, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [16, 1]], [3, 5, 14], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 5], 2, 2], [[4, 3, 'setup'], [4, 5, 'hold']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])], [('setup window boundaries', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [7, 8, 19, 27], 3, 2], [[10, 8, 'setup'], [20, 19, 'setup']]), ('transition exactly at the clock edge', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [20, 22, 29], 3, 2], [[20, 20, 'hold'], [30, 29, 'setup']]), ('falling clock edges are not checked', [0, [[10, 1], [15, 0], [20, 1], [25, 0], [30, 1]], [16, 25], 3, 2], []), ('redundant high transition is not an edge', [0, [[5, 1], [10, 1], [12, 0], [25, 1]], [9, 11], 3, 2], []), ('clock already high at start', [1, [[4, 1], [8, 0], [17, 1]], [3, 5, 15], 2, 2], []), ('clock low at start rises first', [0, [[4, 1], [8, 0], [12, 1]], [3, 6], 2, 2], [[4, 3, 'setup']]), ('overlapping windows reported by edge', [0, [[10, 1], [11, 0], [12, 1]], [11, 12], 3, 3], [[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
setup window boundaries	`[[10, 8, 'setup'], [20, 18, 'setup']]`	`[[10, 8, 'setup'], [20, 18, 'setup']]`	Passed
transition exactly at the clock edge	`[[20, 20, 'hold'], [30, 29, 'setup']]`	`[[20, 20, 'hold'], [30, 29, 'setup']]`	Passed
falling clock edges are not checked	`[]`	`[]`	Passed
redundant high transition is not an edge	`[]`	`[]`	Passed
clock already high at start	`[]`	`[]`	Passed
clock low at start rises first	`[[4, 3, 'setup']]`	`[[4, 3, 'setup']]`	Passed
overlapping windows reported by edge	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']]`	`[[10, 11, 'hold'], [10, 12, 'hold'], [12, 11, 'setup'], [12, 12, 'hold']]`	Passed

SHA-256 / 47ac5ea1d87b401fe3f1327ff41a585799ca5c68825a6481ccae85fa37e750d9

Verification & scope

A deterministic bounded teaching model of one simulator rule set; the contract is stipulated and is not a claim of conformance to any HDL standard or commercial simulator. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:51:12.839385+00:00.

Case digest / 72737f4fd4d2a513162787bfcc22537946882804e1ad93effa1da0836ad5a567