FA-10751 / Raster memory layout / Open access
Pixel unpack alignment · case 01
Row addresses ignore required unpack padding.
ROOT CAUSE
Row addresses ignore required unpack padding.
VERIFIED REPAIR
Use the stage contract: Round nonnegative row-byte length upward to a multiple of positive integer unpack alignment; aligned and empty rows stay unchanged.
Unsuccessful approach: Unconditionally advancing to the next alignment block adds padding to already aligned rows.
Case contract
Round nonnegative row-byte length upward to a multiple of positive integer unpack alignment; aligned and empty rows stay unchanged.
Why this case matters
A deterministic software graphics stage with explicit channel and coordinate conventions; no hardware, device profile or API behavior is inferred.
1 / The failure
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(row_bytes, alignment):
return row_bytes
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(3, 4)), 4)
check('fixture 2', solve(*(4, 4)), 4)
check('fixture 3', solve(*(0, 4)), 0)
check('fixture 4', solve(*(9, 8)), 16)
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 |
|---|---|---|---|
| fixture 1 | 3 | 4 | Failed |
| fixture 2 | 4 | 4 | Passed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 9 | 16 | Failed |
SHA-256 / 62605d7e1ed2171264da05346e1facf1577f58bf5ad62af38a690bda2b133c05
2 / The unsuccessful fix
Exit 1"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(row_bytes, alignment):
return (row_bytes//alignment+1)*alignment
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(3, 4)), 4)
check('fixture 2', solve(*(4, 4)), 4)
check('fixture 3', solve(*(0, 4)), 0)
check('fixture 4', solve(*(9, 8)), 16)
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 |
|---|---|---|---|
| fixture 1 | 4 | 4 | Passed |
| fixture 2 | 8 | 4 | Failed |
| fixture 3 | 4 | 0 | Failed |
| fixture 4 | 16 | 16 | Passed |
SHA-256 / 706b2f96363d6441eafdfdff0e68d67786388f6974cf8dc128b61019a3f9a22f
3 / The verified repair
Exit 0"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(row_bytes, alignment):
return ((row_bytes+alignment-1)//alignment)*alignment
def check(label, actual, expected):
observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('fixture 1', solve(*(3, 4)), 4)
check('fixture 2', solve(*(4, 4)), 4)
check('fixture 3', solve(*(0, 4)), 0)
check('fixture 4', solve(*(9, 8)), 16)
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 |
|---|---|---|---|
| fixture 1 | 4 | 4 | Passed |
| fixture 2 | 4 | 4 | Passed |
| fixture 3 | 0 | 0 | Passed |
| fixture 4 | 16 | 16 | Passed |
SHA-256 / 2313863052478267639f408ab15c0ee5bf8459296df21771da7bef0950c04c02
Verification & scope
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 2026-09-29T14:38:41.885022+00:00.
Case digest / 6b294f6bec565129f965123d9ce00ede253d96dedb571c4d2e6041f46d40d349