FA-52724 / Raster memory layout / Member archive

Small Mip Tail Packing: Large mip directory assumes one page or includes current allocation · case 04

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

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

Mip levels below a threshold share one fixed-size tail page. Larger levels each own whole pages. Tail levels are packed in reverse level order, each with a two-byte tag; tail capacity is caller-provided and sufficient. 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": 348, "large_map": {"0": 28, "1": 92}, "large_pages": [2, 1], "selected": 28, "tail_first": 2, "tail_levels": [4, 3, 2], "tail_map": {"2": 232, "3": 225, "4": 222}, "tail_origin": 220, "tail_spans": [3, 7, 19], "tail_used": 29}`	`{"allocation_end": 348, "large_map": {"0": 28, "1": 156}, "large_pages": [2, 1], "selected": 28, "tail_first": 2, "tail_levels": [4, 3, 2], "tail_map": {"2": 232, "3": 225, "4": 222}, "tail_origin": 220, "tail_spans": [3, 7, 19], "tail_used": 29}`	Failed

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