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b4dbec562f
Reasoning: Image Data Buffers: The `data` parameter of `WebPDequantizeLevels` (in both .c and .h) and `InitParams` (src/utils/quant_levels_dec_utils.c:232) is annotated with `WEBP_SIZED_BY((long)stride * height)`, as it points to the start of the image buffer. The `src` and `dst` fields in `SmoothParams` (src/utils/quant_levels_dec_utils.c:54) are annotated as `WEBP_INDEXABLE`. They are initialized from `data` in `InitParams` (L266) and are advanced row by row using pointer arithmetic (e.g., `p->src += p->stride` in `VFilter` L111, `p->dst += p->stride` in `ApplyFilter` L165). `WEBP_INDEXABLE` is used because the pointers iterate within the buffer and are only accessed with positive indices. Scratch Buffers (`SmoothParams`): Scratch buffers are allocated in `InitParams` via `WebPSafeMalloc`. The local variable `mem` holding this allocation (L245) is explicitly annotated as `WEBP_BIDI_INDEXABLE` to ensure safety when compiling with error suppression. - `start`, `cur`, `top`: These pointers are used for iteration and pointer arithmetic within the circular scratch buffer. They are annotated as `WEBP_INDEXABLE`. - `end`: This pointer is annotated as `WEBP_BIDI_INDEXABLE` because it is used in subtraction (`p->end - width`) in `InitParams` (L257) to calculate `p->top`. - `average`: This buffer is accessed sequentially up to `width`. It is annotated as `WEBP_COUNTED_BY(width)`. Initialization in `InitParams` is reordered (L261) to ensure `p->width` is set before `p->average`. - `correction`: This lookup table requires negative indexing. To avoid using `WEBP_BIDI_INDEXABLE` in the struct, it is annotated as `WEBP_COUNTED_BY_OR_NULL(CORRECTION_LUT_SIZE)` (L75), pointing to the start of the buffer. `CORRECTION_LUT_SIZE` is defined (L33). `InitCorrectionLUT` (L188) and `ApplyFilter` (L147) calculate a local middle pointer which is explicitly annotated as `WEBP_BIDI_INDEXABLE` to allow safe negative indexing. Local Pointers: To ensure safety when compiling with error suppression (where locals default to unsafe), explicit annotations are added to local pointers derived from safe struct members: - `VFilter` (L87): `src`, `cur`, `top`, `out` are `WEBP_INDEXABLE`. - `HFilter` (L121): `in`, `out` are `WEBP_INDEXABLE`. - `ApplyFilter` (L145): `average`, `dst` are `WEBP_INDEXABLE`. - `CountLevels` (L214): `data` is `WEBP_INDEXABLE`. Bug: 432511821 Change-Id: I6bdf86f80c94a5b182c5aef7e4092fe4ea24afb8
40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
// Copyright 2013 Google Inc. All Rights Reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the COPYING file in the root of the source
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// tree. An additional intellectual property rights grant can be found
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// in the file PATENTS. All contributing project authors may
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// be found in the AUTHORS file in the root of the source tree.
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// -----------------------------------------------------------------------------
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//
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// Alpha plane de-quantization utility
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//
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// Author: Vikas Arora (vikasa@google.com)
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#ifndef WEBP_UTILS_QUANT_LEVELS_DEC_UTILS_H_
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#define WEBP_UTILS_QUANT_LEVELS_DEC_UTILS_H_
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#include "src/utils/bounds_safety.h"
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#include "src/webp/types.h"
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WEBP_ASSUME_UNSAFE_INDEXABLE_ABI
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#ifdef __cplusplus
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extern "C" {
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#endif
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// Apply post-processing to input 'data' of size 'width'x'height' assuming that
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// the source was quantized to a reduced number of levels. 'stride' is in bytes.
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// Strength is in [0..100] and controls the amount of dithering applied.
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// Returns false in case of error (data is NULL, invalid parameters,
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// malloc failure, ...).
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int WebPDequantizeLevels(uint8_t* WEBP_SIZED_BY((size_t)stride* height)
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const data,
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int width, int height, int stride, int strength);
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // WEBP_UTILS_QUANT_LEVELS_DEC_UTILS_H_
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