FA-52962 / Raster memory layout / Member archive

Scanline Scatter Gather: Second segment assumes physical adjacency or loses pixel width · case 02

The returned physical layout descriptor disagrees with the declared buffer mapping at right_start.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

A raster readback maps each row to two caller-provided physical segments. Segment boundary is a pixel index, not a byte count; segment two has its own noncontiguous origin. A requested valid x range becomes up to two byte spans. Return the named intermediate layout descriptor and final address fields; all quantities are integer byte offsets unless explicitly stated.

Why this case matters

Offline raster resource, upload, readback, and storage-layout regression model.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
layout fixture 1	`{"destination_offsets": [], "left_bytes": 0, "left_count": 0, "left_start": 114, "right_bytes": 0, "right_count": 0, "right_local": 0, "right_start": 126, "spans": [], "total_bytes": 0}`	`{"destination_offsets": [], "left_bytes": 0, "left_count": 0, "left_start": 114, "right_bytes": 0, "right_count": 0, "right_local": 0, "right_start": 400, "spans": [], "total_bytes": 0}`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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