FA-52574 / Raster memory layout / Member archive

Variable Scanline Packets: Payload begins at tag or skips first encoded byte · case 04

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

Member previewVariant 4 · 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 1	`{"allocation_end": 87, "directory_bytes": 20, "directory_entry": 36, "packet_origins": [56, 63, 66, 72, 76], "packet_sizes": [7, 3, 6, 4, 11], "payload_end": 60, "payload_start": 56, "relative_offsets": [0, 7, 10, 16, 20], "rows": 5, "terminator": 60}`	`{"allocation_end": 87, "directory_bytes": 20, "directory_entry": 36, "packet_origins": [56, 63, 66, 72, 76], "packet_sizes": [7, 3, 6, 4, 11], "payload_end": 62, "payload_start": 58, "relative_offsets": [0, 7, 10, 16, 20], "rows": 5, "terminator": 62}`	Failed

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