FA-52568 / Raster memory layout / Member archive

Variable Scanline Packets: Directory slot uses byte index or skips first record · case 03

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

Member previewVariant 3 · 3 implementations · 6 checks per implementation

Case contract

Each scanline is a packet with a two-byte tag, a four-byte absolute-offset directory entry, and a caller-specified encoded payload length. The directory precedes packet bytes; a trailing one-byte terminator follows each packet. 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 2	`{"allocation_end": 77, "directory_bytes": 20, "directory_entry": 28, "packet_origins": [47, 54, 57, 64, 68], "packet_sizes": [7, 3, 7, 4, 9], "payload_end": 56, "payload_start": 56, "relative_offsets": [0, 7, 10, 17, 21], "rows": 5, "terminator": 56}`	`{"allocation_end": 77, "directory_bytes": 20, "directory_entry": 31, "packet_origins": [47, 54, 57, 64, 68], "packet_sizes": [7, 3, 7, 4, 9], "payload_end": 56, "payload_start": 56, "relative_offsets": [0, 7, 10, 17, 21], "rows": 5, "terminator": 56}`	Failed

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