FA-92091 / PLC ladder logic scan cycles / Open access

Sequencer write clobbers destination bits outside the mask · case 01

Outputs that other rungs control on the same word are cleared on every sequencer step.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The destination is overwritten with the masked word.

VERIFIED REPAIR

Preserve unmasked destination bits and replace only masked bits.

Unsuccessful approach: ORing the masked word in never clears masked bits from the previous step.

Case contract

Sequencer output (SQO). words is the sequencer file whose element 0 is the home step; position starts at 0. On each rising edge of enable the position advances; past the last element it wraps to 1 (not 0). Each advance writes dest = (dest AND NOT mask) OR (word AND mask) in 16 bits. A reset input returns position to 0 without writing dest and has priority over a coincident advance; the enable edge memory is always updated. steps is a list of [enable, reset]; return [position, dest] per scan.

Why this case matters

Ladder programs are executed as repeated scans; each defect here changes what a rung, timer, counter or data-table instruction reports on a particular scan, which is how commissioning and field faults are actually observed.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(words, mask, start_dest, steps):
    pos = 0
    dest = start_dest
    prev = False
    length = len(words) - 1
    out = []
    for en, res in steps:
        en = bool(en)
        if res:
            pos = 0
        elif en and not prev:
            pos += 1
            if pos > length:
                pos = 1
            dest = words[pos] & mask
        prev = en
        out.append([pos, dest])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['regression: scenario 1',
   [[26918, 50611, 8879, 59828],
    65535,
    52597,
    [[False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False]]],
   [[0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [1, 50611],
    [1, 50611],
    [1, 50611]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[42968, 29173, 43546],
    255,
    5794,
    [[True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False]]],
   [[1, 5877],
    [1, 5877],
    [1, 5877],
    [1, 5877],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [0, 5658],
    [0, 5658]]],
  ['regression: scenario 3',
   [[16785, 47110, 21847, 45361],
    61440,
    41889,
    [[True, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False]]],
   [[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]],
  ['regression: scenario 4',
   [[26660, 61415, 54040],
    65535,
    45106,
    [[True, False], [True, False], [True, False], [False, False], [False, False], [True, False]]],
   [[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]]],
 [['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[8488, 43469, 38296, 4034],
    255,
    44563,
    [[False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False]]],
   [[0, 44563],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [2, 44696],
    [2, 44696],
    [3, 44738],
    [3, 44738],
    [1, 44749],
    [1, 44749],
    [2, 44696]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[43079, 20640, 23622, 26553],
    255,
    15109,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, True]]],
   [[0, 15109],
    [0, 15109],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [3, 15289],
    [0, 15289]]],
  ['regression: scenario 3',
   [[16618, 36272, 41924, 55813],
    3855,
    48911,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 48384], [1, 48384], [1, 48384], [1, 48384], [1, 48384], [2, 45828], [2, 45828]]],
  ['regression: scenario 4',
   [[45574, 2941],
    255,
    15355,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False]]],
   [[0, 15355],
    [0, 15355],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229]]]],
 [['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[36741, 30504],
    65535,
    26589,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [True, False],
     [False, False]]],
   [[1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [0, 30504],
    [0, 30504],
    [0, 30504]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[38610, 2229],
    65535,
    14704,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, True],
     [False, False]]],
   [[0, 14704], [0, 14704], [0, 14704], [0, 14704], [0, 14704], [1, 2229], [1, 2229], [0, 2229], [0, 2229]]],
  ['regression: scenario 3',
   [[45414, 65173, 31151, 4829],
    3855,
    46402,
    [[False, True],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False]]],
   [[0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [1, 48709],
    [1, 48709],
    [1, 48709]]],
  ['regression: scenario 4',
   [[29784, 63854],
    255,
    25258,
    [[False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 25258],
    [1, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [0, 25198]]]],
 [['regression: scenario 1',
   [[61786, 58708],
    255,
    45362,
    [[False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[0, 45362], [0, 45362], [0, 45362], [1, 45396], [1, 45396], [1, 45396], [1, 45396]]],
  ['regression: scenario 5',
   [[47154, 32327, 23912, 32399],
    3855,
    21368,
    [[False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 21368],
    [0, 21368],
    [0, 21368],
    [1, 24183],
    [1, 24183],
    [1, 24183],
    [2, 23928],
    [2, 23928],
    [2, 23928],
    [3, 24191],
    [0, 24191]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[57902, 51779],
    61440,
    26811,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387]]],
  ['regression: scenario 3',
   [[35305, 48952, 41314, 29239, 28773],
    65535,
    11028,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True]]],
   [[0, 11028],
    [0, 11028],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [0, 41314]]]],
 [['regression: scenario 2',
   [[43067, 57880, 6921, 33106, 51712],
    255,
    13830,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, True],
     [True, True],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 13848],
    [1, 13848],
    [1, 13848],
    [2, 13833],
    [2, 13833],
    [2, 13833],
    [3, 13906],
    [3, 13906],
    [0, 13906],
    [0, 13906],
    [0, 13906],
    [1, 13848],
    [1, 13848]]],
  ['regression: scenario 6',
   [[49875, 17863, 34135],
    3855,
    57202,
    [[False, False], [True, False], [True, False], [True, True], [False, False], [False, False]]],
   [[0, 57202], [1, 54647], [1, 54647], [0, 54647], [0, 54647], [0, 54647]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 1',
   [[39974, 26951],
    3855,
    4546,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 4546],
    [0, 4546],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [0, 6599]]],
  ['regression: scenario 3',
   [[62662, 46394, 25376, 46313],
    3855,
    7057,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [1, 5530],
    [1, 5530],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [3, 5273],
    [3, 5273]]]]]
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
regression: wrap past last step	`[[1, 17], [1, 17], [2, 34], [2, 34], [1, 17], [1, 17]]`	`[[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]`	Failed
regression: scenario 1	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 50611], [1, 50611], [1, 50611]]`	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 50611], [1, 50611], [1, 50611]]`	Passed
control: two element file	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	Passed
regression: reset while enabled	`[[1, 3], [0, 3], [0, 3], [1, 3]]`	`[[1, 65523], [0, 65523], [0, 65523], [1, 65523]]`	Failed
regression: reset with advance	`[[0, 170], [0, 170], [0, 170], [1, 256]]`	`[[0, 170], [0, 170], [0, 170], [1, 426]]`	Failed
regression: scenario 2	`[[1, 245], [1, 245], [1, 245], [1, 245], [2, 26], [2, 26], [2, 26], [2, 26], [0, 26], [0, 26]]`	`[[1, 5877], [1, 5877], [1, 5877], [1, 5877], [2, 5658], [2, 5658], [2, 5658], [2, 5658], [0, 5658], [0, 5658]]`	Failed
regression: scenario 3	`[[1, 45056], [1, 45056], [1, 45056], [1, 45056], [1, 45056], [1, 45056], [1, 45056]]`	`[[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]`	Failed
regression: scenario 4	`[[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]`	`[[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]`	Passed

SHA-256 / 868c6135d8fb3a2ee0222ff155a3d30dd835849b380f2bd469c0fcdb00869d1b

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(words, mask, start_dest, steps):
    pos = 0
    dest = start_dest
    prev = False
    length = len(words) - 1
    out = []
    for en, res in steps:
        en = bool(en)
        if res:
            pos = 0
        elif en and not prev:
            pos += 1
            if pos > length:
                pos = 1
            dest = dest | (words[pos] & mask)
        prev = en
        out.append([pos, dest])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['regression: scenario 1',
   [[26918, 50611, 8879, 59828],
    65535,
    52597,
    [[False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False]]],
   [[0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [1, 50611],
    [1, 50611],
    [1, 50611]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[42968, 29173, 43546],
    255,
    5794,
    [[True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False]]],
   [[1, 5877],
    [1, 5877],
    [1, 5877],
    [1, 5877],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [0, 5658],
    [0, 5658]]],
  ['regression: scenario 3',
   [[16785, 47110, 21847, 45361],
    61440,
    41889,
    [[True, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False]]],
   [[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]],
  ['regression: scenario 4',
   [[26660, 61415, 54040],
    65535,
    45106,
    [[True, False], [True, False], [True, False], [False, False], [False, False], [True, False]]],
   [[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]]],
 [['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[8488, 43469, 38296, 4034],
    255,
    44563,
    [[False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False]]],
   [[0, 44563],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [2, 44696],
    [2, 44696],
    [3, 44738],
    [3, 44738],
    [1, 44749],
    [1, 44749],
    [2, 44696]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[43079, 20640, 23622, 26553],
    255,
    15109,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, True]]],
   [[0, 15109],
    [0, 15109],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [3, 15289],
    [0, 15289]]],
  ['regression: scenario 3',
   [[16618, 36272, 41924, 55813],
    3855,
    48911,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 48384], [1, 48384], [1, 48384], [1, 48384], [1, 48384], [2, 45828], [2, 45828]]],
  ['regression: scenario 4',
   [[45574, 2941],
    255,
    15355,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False]]],
   [[0, 15355],
    [0, 15355],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229]]]],
 [['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[36741, 30504],
    65535,
    26589,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [True, False],
     [False, False]]],
   [[1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [0, 30504],
    [0, 30504],
    [0, 30504]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[38610, 2229],
    65535,
    14704,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, True],
     [False, False]]],
   [[0, 14704], [0, 14704], [0, 14704], [0, 14704], [0, 14704], [1, 2229], [1, 2229], [0, 2229], [0, 2229]]],
  ['regression: scenario 3',
   [[45414, 65173, 31151, 4829],
    3855,
    46402,
    [[False, True],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False]]],
   [[0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [1, 48709],
    [1, 48709],
    [1, 48709]]],
  ['regression: scenario 4',
   [[29784, 63854],
    255,
    25258,
    [[False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 25258],
    [1, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [0, 25198]]]],
 [['regression: scenario 1',
   [[61786, 58708],
    255,
    45362,
    [[False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[0, 45362], [0, 45362], [0, 45362], [1, 45396], [1, 45396], [1, 45396], [1, 45396]]],
  ['regression: scenario 5',
   [[47154, 32327, 23912, 32399],
    3855,
    21368,
    [[False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 21368],
    [0, 21368],
    [0, 21368],
    [1, 24183],
    [1, 24183],
    [1, 24183],
    [2, 23928],
    [2, 23928],
    [2, 23928],
    [3, 24191],
    [0, 24191]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[57902, 51779],
    61440,
    26811,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387]]],
  ['regression: scenario 3',
   [[35305, 48952, 41314, 29239, 28773],
    65535,
    11028,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True]]],
   [[0, 11028],
    [0, 11028],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [0, 41314]]]],
 [['regression: scenario 2',
   [[43067, 57880, 6921, 33106, 51712],
    255,
    13830,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, True],
     [True, True],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 13848],
    [1, 13848],
    [1, 13848],
    [2, 13833],
    [2, 13833],
    [2, 13833],
    [3, 13906],
    [3, 13906],
    [0, 13906],
    [0, 13906],
    [0, 13906],
    [1, 13848],
    [1, 13848]]],
  ['regression: scenario 6',
   [[49875, 17863, 34135],
    3855,
    57202,
    [[False, False], [True, False], [True, False], [True, True], [False, False], [False, False]]],
   [[0, 57202], [1, 54647], [1, 54647], [0, 54647], [0, 54647], [0, 54647]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 1',
   [[39974, 26951],
    3855,
    4546,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 4546],
    [0, 4546],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [0, 6599]]],
  ['regression: scenario 3',
   [[62662, 46394, 25376, 46313],
    3855,
    7057,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [1, 5530],
    [1, 5530],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [3, 5273],
    [3, 5273]]]]]
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
regression: wrap past last step	`[[1, 43793], [1, 43793], [2, 43827], [2, 43827], [1, 43827], [1, 43827]]`	`[[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]`	Failed
regression: scenario 1	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 52727], [1, 52727], [1, 52727]]`	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 50611], [1, 50611], [1, 50611]]`	Failed
control: two element file	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	Passed
regression: reset while enabled	`[[1, 65523], [0, 65523], [0, 65523], [1, 65523]]`	`[[1, 65523], [0, 65523], [0, 65523], [1, 65523]]`	Passed
regression: reset with advance	`[[0, 170], [0, 170], [0, 170], [1, 426]]`	`[[0, 170], [0, 170], [0, 170], [1, 426]]`	Passed
regression: scenario 2	`[[1, 5879], [1, 5879], [1, 5879], [1, 5879], [2, 5887], [2, 5887], [2, 5887], [2, 5887], [0, 5887], [0, 5887]]`	`[[1, 5877], [1, 5877], [1, 5877], [1, 5877], [2, 5658], [2, 5658], [2, 5658], [2, 5658], [0, 5658], [0, 5658]]`	Failed
regression: scenario 3	`[[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]`	`[[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]`	Passed
regression: scenario 4	`[[1, 65527], [1, 65527], [1, 65527], [1, 65527], [1, 65527], [2, 65535]]`	`[[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]`	Failed

SHA-256 / a359800df538eb6914f8b8d8f1c8c45ca0976f3b275472273740261d74f6c944

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(words, mask, start_dest, steps):
    pos = 0
    dest = start_dest
    prev = False
    length = len(words) - 1
    out = []
    for en, res in steps:
        en = bool(en)
        if res:
            pos = 0
        elif en and not prev:
            pos += 1
            if pos > length:
                pos = 1
            dest = (dest & ~mask & 0xFFFF) | (words[pos] & mask)
        prev = en
        out.append([pos, dest])
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['regression: scenario 1',
   [[26918, 50611, 8879, 59828],
    65535,
    52597,
    [[False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False]]],
   [[0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [0, 52597],
    [1, 50611],
    [1, 50611],
    [1, 50611]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[42968, 29173, 43546],
    255,
    5794,
    [[True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [False, False]]],
   [[1, 5877],
    [1, 5877],
    [1, 5877],
    [1, 5877],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [2, 5658],
    [0, 5658],
    [0, 5658]]],
  ['regression: scenario 3',
   [[16785, 47110, 21847, 45361],
    61440,
    41889,
    [[True, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False]]],
   [[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]],
  ['regression: scenario 4',
   [[26660, 61415, 54040],
    65535,
    45106,
    [[True, False], [True, False], [True, False], [False, False], [False, False], [True, False]]],
   [[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]]],
 [['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[8488, 43469, 38296, 4034],
    255,
    44563,
    [[False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False]]],
   [[0, 44563],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [1, 44749],
    [2, 44696],
    [2, 44696],
    [3, 44738],
    [3, 44738],
    [1, 44749],
    [1, 44749],
    [2, 44696]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[43079, 20640, 23622, 26553],
    255,
    15109,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, True]]],
   [[0, 15109],
    [0, 15109],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [1, 15264],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [2, 15174],
    [3, 15289],
    [0, 15289]]],
  ['regression: scenario 3',
   [[16618, 36272, 41924, 55813],
    3855,
    48911,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 48384], [1, 48384], [1, 48384], [1, 48384], [1, 48384], [2, 45828], [2, 45828]]],
  ['regression: scenario 4',
   [[45574, 2941],
    255,
    15355,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False]]],
   [[0, 15355],
    [0, 15355],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229],
    [1, 15229]]]],
 [['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[36741, 30504],
    65535,
    26589,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [False, False],
     [True, True],
     [True, False],
     [False, False]]],
   [[1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [1, 30504],
    [0, 30504],
    [0, 30504],
    [0, 30504]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: scenario 1',
   [[38610, 2229],
    65535,
    14704,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, True],
     [False, False]]],
   [[0, 14704], [0, 14704], [0, 14704], [0, 14704], [0, 14704], [1, 2229], [1, 2229], [0, 2229], [0, 2229]]],
  ['regression: scenario 3',
   [[45414, 65173, 31151, 4829],
    3855,
    46402,
    [[False, True],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False]]],
   [[0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [0, 46402],
    [1, 48709],
    [1, 48709],
    [1, 48709]]],
  ['regression: scenario 4',
   [[29784, 63854],
    255,
    25258,
    [[False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 25258],
    [1, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [1, 25198],
    [0, 25198],
    [0, 25198],
    [0, 25198],
    [1, 25198],
    [0, 25198]]]],
 [['regression: scenario 1',
   [[61786, 58708],
    255,
    45362,
    [[False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[0, 45362], [0, 45362], [0, 45362], [1, 45396], [1, 45396], [1, 45396], [1, 45396]]],
  ['regression: scenario 5',
   [[47154, 32327, 23912, 32399],
    3855,
    21368,
    [[False, True],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 21368],
    [0, 21368],
    [0, 21368],
    [1, 24183],
    [1, 24183],
    [1, 24183],
    [2, 23928],
    [2, 23928],
    [2, 23928],
    [3, 24191],
    [0, 24191]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 2',
   [[57902, 51779],
    61440,
    26811,
    [[True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False]]],
   [[1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387], [1, 51387]]],
  ['regression: scenario 3',
   [[35305, 48952, 41314, 29239, 28773],
    65535,
    11028,
    [[False, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, True]]],
   [[0, 11028],
    [0, 11028],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [1, 48952],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [2, 41314],
    [0, 41314]]]],
 [['regression: scenario 2',
   [[43067, 57880, 6921, 33106, 51712],
    255,
    13830,
    [[True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False],
     [True, True],
     [True, True],
     [False, False],
     [True, False],
     [False, False]]],
   [[1, 13848],
    [1, 13848],
    [1, 13848],
    [2, 13833],
    [2, 13833],
    [2, 13833],
    [3, 13906],
    [3, 13906],
    [0, 13906],
    [0, 13906],
    [0, 13906],
    [1, 13848],
    [1, 13848]]],
  ['regression: scenario 6',
   [[49875, 17863, 34135],
    3855,
    57202,
    [[False, False], [True, False], [True, False], [True, True], [False, False], [False, False]]],
   [[0, 57202], [1, 54647], [1, 54647], [0, 54647], [0, 54647], [0, 54647]]],
  ['regression: wrap past last step',
   [[0, 17, 34],
    255,
    43776,
    [[True, False], [False, False], [True, False], [False, False], [True, False], [True, False]]],
   [[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]],
  ['control: two element file',
   [[5, 9], 65535, 0, [[True, False], [False, False], [True, False], [False, False], [True, False]]],
   [[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]],
  ['regression: reset while enabled',
   [[0, 3, 12], 15, 65520, [[True, False], [True, True], [False, False], [True, False]]],
   [[1, 65523], [0, 65523], [0, 65523], [1, 65523]]],
  ['regression: reset with advance',
   [[0, 256, 512], 65280, 170, [[False, False], [True, True], [False, False], [True, False]]],
   [[0, 170], [0, 170], [0, 170], [1, 426]]],
  ['regression: scenario 1',
   [[39974, 26951],
    3855,
    4546,
    [[False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [False, False],
     [False, False],
     [True, False],
     [True, True]]],
   [[0, 4546],
    [0, 4546],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [1, 6599],
    [0, 6599]]],
  ['regression: scenario 3',
   [[62662, 46394, 25376, 46313],
    3855,
    7057,
    [[False, False],
     [False, False],
     [False, False],
     [False, False],
     [False, False],
     [True, False],
     [False, False],
     [True, False],
     [True, False],
     [True, False],
     [False, False],
     [True, False],
     [False, False]]],
   [[0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [0, 7057],
    [1, 5530],
    [1, 5530],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [2, 5008],
    [3, 5273],
    [3, 5273]]]]]
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
regression: wrap past last step	`[[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]`	`[[1, 43793], [1, 43793], [2, 43810], [2, 43810], [1, 43793], [1, 43793]]`	Passed
regression: scenario 1	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 50611], [1, 50611], [1, 50611]]`	`[[0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [0, 52597], [1, 50611], [1, 50611], [1, 50611]]`	Passed
control: two element file	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	`[[1, 9], [1, 9], [1, 9], [1, 9], [1, 9]]`	Passed
regression: reset while enabled	`[[1, 65523], [0, 65523], [0, 65523], [1, 65523]]`	`[[1, 65523], [0, 65523], [0, 65523], [1, 65523]]`	Passed
regression: reset with advance	`[[0, 170], [0, 170], [0, 170], [1, 426]]`	`[[0, 170], [0, 170], [0, 170], [1, 426]]`	Passed
regression: scenario 2	`[[1, 5877], [1, 5877], [1, 5877], [1, 5877], [2, 5658], [2, 5658], [2, 5658], [2, 5658], [0, 5658], [0, 5658]]`	`[[1, 5877], [1, 5877], [1, 5877], [1, 5877], [2, 5658], [2, 5658], [2, 5658], [2, 5658], [0, 5658], [0, 5658]]`	Passed
regression: scenario 3	`[[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]`	`[[1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985], [1, 45985]]`	Passed
regression: scenario 4	`[[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]`	`[[1, 61415], [1, 61415], [1, 61415], [1, 61415], [1, 61415], [2, 54040]]`	Passed

SHA-256 / 3d29531f8e01b476051aebffb8f672221f785b3688d14e3c7ef26c281fed43b8

Verification & scope

A deterministic bounded teaching model of one PLC instruction or rung pattern evaluated scan by scan. The stated contract is a stipulated toy convention, not a claim of conformance to any vendor controller or IEC 61131-3 runtime. 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 2026-09-29T14:51:42.448326+00:00.

Case digest / bd58eee7cf8ad042001493193c0275d5ffc0d0290737ba84afad09bfa3f0781d