FA-52400 / Raster memory layout / Member archive

Indexed Nibble Records: Nibble rows discard odd pixel or allocate one byte per pixel · case 05

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

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

An indexed image has a palette of three-byte entries, a two-byte palette-count field, and high-nibble-first pixels. Each scanline starts with a one-byte checksum. Odd final low nibbles are padding. 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": 129, "byte_address": 120, "image_origin": 114, "keep_mask": 240, "packed_bytes": 4, "palette_bytes": 29, "row_pitch": 5, "shift": 0, "tail_mask": 240, "written_byte": 38}`	`{"allocation_end": 132, "byte_address": 121, "image_origin": 114, "keep_mask": 240, "packed_bytes": 5, "palette_bytes": 29, "row_pitch": 6, "shift": 0, "tail_mask": 240, "written_byte": 38}`	Failed

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

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