FAILURE MAP
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FA-48931 / PCM sample encoding / Open access

Ones complement pcm: negative zero tag · case 01

Negative zero is confused with the largest negative code.

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

ROOT CAUSE

Negative zero is confused with the largest negative code.

VERIFIED REPAIR

Use the stated conversion contract at negative zero tag.

Unsuccessful approach: Tagging positive zero merges the two wire zero representations.

Case contract

Decode bounded ones-complement PCM fields; optionally preserve a per-sample negative-zero sideband while numeric zero stays JSON integer zero.

Why this case matters

Offline PCM interchange uses these exact bounded packet and sample representation decisions.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(codes, width, preserve_negative_zero):
    mask=(1<<width)-1
    sign=1<<(width-1)
    values=[]
    negative_zero=[]
    for raw in codes:
        code=raw&mask
        magnitude=(~code)&mask if code&sign else code
        value=-magnitude if code&sign else magnitude
        values.append(value)
        negative_zero.append(bool(preserve_negative_zero and code==sign))
    return [values,negative_zero]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 7, 8, 14, 15], 4, True)), [[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]])
check('oracle 2', solve(*([15, 0, 8], 4, False)), [[0, 0, -7], [False, False, False]])
check('oracle 3', solve(*([31, 16, 17], 4, True)), [[0, 0, 1], [True, False, False]])
check('oracle 4', solve(*([], 4, True)), [[], []])
check('oracle 5', solve(*([0, 3, 4, 6, 7], 3, True)), [[0, 3, -3, -1, 0], [False, False, False, False, True]])
check('oracle 6', solve(*([255, 128, 254, 127], 8, False)), [[0, -127, -1, 127], [False, False, False, False]])
check('oracle 7', solve(*([255], 8, True)), [[0], [True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
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 fixtureActualExpectedOutcome
oracle 1[[0, 1, 7, -7, -1, 0], [False, False, False, True, False, False]][[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]]Failed
oracle 2[[0, 0, -7], [False, False, False]][[0, 0, -7], [False, False, False]]Passed
oracle 3[[0, 0, 1], [False, False, False]][[0, 0, 1], [True, False, False]]Failed
oracle 4[[], []][[], []]Passed
oracle 5[[0, 3, -3, -1, 0], [False, False, True, False, False]][[0, 3, -3, -1, 0], [False, False, False, False, True]]Failed
oracle 6[[0, -127, -1, 127], [False, False, False, False]][[0, -127, -1, 127], [False, False, False, False]]Passed
oracle 7[[0], [False]][[0], [True]]Failed
variant packet 1[[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, True, False, False, False, False, False, True, False, False]][[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]]Failed

SHA-256 / 0d413fb26e4745cb5add600678cce88cda524009cf79f9f395abd90f53edbd00

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(codes, width, preserve_negative_zero):
    mask=(1<<width)-1
    sign=1<<(width-1)
    values=[]
    negative_zero=[]
    for raw in codes:
        code=raw&mask
        magnitude=(~code)&mask if code&sign else code
        value=-magnitude if code&sign else magnitude
        values.append(value)
        negative_zero.append(bool(preserve_negative_zero and code==0))
    return [values,negative_zero]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 7, 8, 14, 15], 4, True)), [[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]])
check('oracle 2', solve(*([15, 0, 8], 4, False)), [[0, 0, -7], [False, False, False]])
check('oracle 3', solve(*([31, 16, 17], 4, True)), [[0, 0, 1], [True, False, False]])
check('oracle 4', solve(*([], 4, True)), [[], []])
check('oracle 5', solve(*([0, 3, 4, 6, 7], 3, True)), [[0, 3, -3, -1, 0], [False, False, False, False, True]])
check('oracle 6', solve(*([255, 128, 254, 127], 8, False)), [[0, -127, -1, 127], [False, False, False, False]])
check('oracle 7', solve(*([255], 8, True)), [[0], [True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
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 fixtureActualExpectedOutcome
oracle 1[[0, 1, 7, -7, -1, 0], [True, False, False, False, False, False]][[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]]Failed
oracle 2[[0, 0, -7], [False, False, False]][[0, 0, -7], [False, False, False]]Passed
oracle 3[[0, 0, 1], [False, True, False]][[0, 0, 1], [True, False, False]]Failed
oracle 4[[], []][[], []]Passed
oracle 5[[0, 3, -3, -1, 0], [True, False, False, False, False]][[0, 3, -3, -1, 0], [False, False, False, False, True]]Failed
oracle 6[[0, -127, -1, 127], [False, False, False, False]][[0, -127, -1, 127], [False, False, False, False]]Passed
oracle 7[[0], [False]][[0], [True]]Failed
variant packet 1[[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [True, False, False, False, False, False, True, False, False, False, False, False]][[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]]Failed

SHA-256 / f15d42c47134179afd9eb1383d603825c6bbac0f545c83bff543552a6eddbbf1

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(codes, width, preserve_negative_zero):
    mask=(1<<width)-1
    sign=1<<(width-1)
    values=[]
    negative_zero=[]
    for raw in codes:
        code=raw&mask
        magnitude=(~code)&mask if code&sign else code
        value=-magnitude if code&sign else magnitude
        values.append(value)
        negative_zero.append(bool(preserve_negative_zero and code==mask))
    return [values,negative_zero]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('oracle 1', solve(*([0, 1, 7, 8, 14, 15], 4, True)), [[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]])
check('oracle 2', solve(*([15, 0, 8], 4, False)), [[0, 0, -7], [False, False, False]])
check('oracle 3', solve(*([31, 16, 17], 4, True)), [[0, 0, 1], [True, False, False]])
check('oracle 4', solve(*([], 4, True)), [[], []])
check('oracle 5', solve(*([0, 3, 4, 6, 7], 3, True)), [[0, 3, -3, -1, 0], [False, False, False, False, True]])
check('oracle 6', solve(*([255, 128, 254, 127], 8, False)), [[0, -127, -1, 127], [False, False, False, False]])
check('oracle 7', solve(*([255], 8, True)), [[0], [True]])
if N == 1: check('variant packet 1', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 2: check('variant packet 2', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 3: check('variant packet 3', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 4: check('variant packet 4', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
if N == 5: check('variant packet 5', solve(*[[0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15, 0, 1, 7, 8, 14, 15], 4, True]), [[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True, False, False, False, False, False, True]])
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 fixtureActualExpectedOutcome
oracle 1[[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]][[0, 1, 7, -7, -1, 0], [False, False, False, False, False, True]]Passed
oracle 2[[0, 0, -7], [False, False, False]][[0, 0, -7], [False, False, False]]Passed
oracle 3[[0, 0, 1], [True, False, False]][[0, 0, 1], [True, False, False]]Passed
oracle 4[[], []][[], []]Passed
oracle 5[[0, 3, -3, -1, 0], [False, False, False, False, True]][[0, 3, -3, -1, 0], [False, False, False, False, True]]Passed
oracle 6[[0, -127, -1, 127], [False, False, False, False]][[0, -127, -1, 127], [False, False, False, False]]Passed
oracle 7[[0], [True]][[0], [True]]Passed
variant packet 1[[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]][[0, 1, 7, -7, -1, 0, 0, 1, 7, -7, -1, 0], [False, False, False, False, False, True, False, False, False, False, False, True]]Passed

SHA-256 / e991dcf69ef6c0014180a5e9626eb25028eb8dc585a04e5476bb6788b9e02244

Verification & scope

Stipulated finite model; no claim of hardware timing or full file-format conformance. 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 2026-09-29T14:44:55.264582+00:00.

Case digest / bb6356d9a59d095838159670e89465e443b4efbaf82f36ef4d226c2560b047fb