FA-52370 / Raster memory layout / Member archive

Bitplane Word Storage: Pixel-to-word lookup uses byte packing or local bit index · case 05

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

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

A four-plane bitmap uses sixteen-bit words, most-significant-bit-first pixels, independent plane headers, and plane-major storage. Each row contains an extra sentinel word. Return word location and update mask without decoding colors. 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 3	`{"address": 129, "bit_index": 0, "last_word_mask": 65280, "mask": 1, "plane_bytes": 28, "plane_origin": 115, "row_bytes": 6, "row_words": 3, "word_column": 1, "words": 2}`	`{"address": 127, "bit_index": 0, "last_word_mask": 65280, "mask": 1, "plane_bytes": 28, "plane_origin": 115, "row_bytes": 6, "row_words": 3, "word_column": 0, "words": 2}`	Failed

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