leonarski_fandClaude Opus 5.5
f4252ad39d
The CBF reader decoded every frame's x-CBF_BYTE_OFFSET stream on the worker thread - 19-30 % of the image-loop worker CPU on CBF sets (7qij, 4mtk) - and the 4-byte image was then uploaded. ReadRawImage now hands over the stream as the file stores it, in the image's own buffer, as a new read-only CompressionAlgorithm::CBF_BYTE_OFFSET (mode Int32, what it decodes to), and ImagePreprocessorGPU decodes it on the card into the same int32 image and runs the same preprocessing kernel on it. The device decode (CBFDecoderGPU) cuts the stream into 256-byte tiles. A token is 1, 3, 7 or 15 bytes, so a tile can be entered at 15 offsets; for each one thread works out where the decode leaves the tile, how many pixels it emitted and their sum modulo 2^32 (the walks from different entries meet within a few bytes, after which they are one walk). An exclusive scan composing these maps gives each tile its true entry, first pixel and running value, and a second walk writes the pixels. A stream that ends before the image is refused as on the host. The host decoder moves to compression/ (DecodeCBFByteOffset) and is reached through JFJochDecompressPtr, so every host consumer - the CPU build, the azimuthal-integration worker, the pre-scan's shadow and gain passes - decodes exactly as before, now from the stream. It is the CPU path, not a fallback: a frame the device refuses is not retried on the host. A process file written from CBF input stores the decoded int32 image, as it always did. .cbf.gz is still inflated on the host. Tests: CBFDecoderGPU_MatchesHost (every token size, 0x80 inside payloads, escape runs across tiles, trailing CIF text), CBFDecoderGPU_ShortStreamIsRefused, ImagePreprocessorGPU_StoredEncodingsMatchCPU. Checked locally against the host decoder on 36 real frames of 9 open-arm CBF sets (signed 32-bit, signed and unsigned 16-bit, plain and gzip): identical. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EizBKhTqrAYago9KJG3dA3
13 lines
561 B
C++
13 lines
561 B
C++
// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
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// SPDX-License-Identifier: GPL-3.0-only
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#pragma once
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#include <cstddef>
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#include <cstdint>
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// x-CBF_BYTE_OFFSET -> int32. Deltas against a running value, smallest container first: int8,
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// escaping to int16 via -128, to int32 via -32768, to int64 via INT32_MIN. Little-endian, packed.
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// Throws if the stream ends before n_pixels are produced. out must hold n_pixels.
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void DecodeCBFByteOffset(const uint8_t *data, size_t size, int32_t *out, size_t n_pixels);
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