mirror of
https://github.com/cocos/cocos-engine.git
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75 lines
3.2 KiB
C++
75 lines
3.2 KiB
C++
/****************************************************************************
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Copyright (c) 2010-2012 cocos2d-x.org
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Copyright (c) 2013-2016 Chukong Technologies Inc.
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Copyright (c) 2017-2022 Xiamen Yaji Software Co., Ltd.
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http://www.cocos.com
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated engine source code (the "Software"), a limited,
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worldwide, royalty-free, non-assignable, revocable and non-exclusive license
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to use Cocos Creator solely to develop games on your target platforms. You shall
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not use Cocos Creator software for developing other software or tools that's
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used for developing games. You are not granted to publish, distribute,
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sublicense, and/or sell copies of Cocos Creator.
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The software or tools in this License Agreement are licensed, not sold.
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Xiamen Yaji Software Co., Ltd. reserves all rights not expressly granted to you.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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****************************************************************************/
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#include "base/etc2.h"
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#include <stdint.h>
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#include <string.h>
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static const char kMagic[] = {'P', 'K', 'M', ' ', '2', '0'};
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static const etc2_uint32 ETC2_PKM_FORMAT_OFFSET = 6;
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static const etc2_uint32 ETC2_PKM_ENCODED_WIDTH_OFFSET = 8;
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static const etc2_uint32 ETC2_PKM_ENCODED_HEIGHT_OFFSET = 10;
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static const etc2_uint32 ETC2_PKM_WIDTH_OFFSET = 12;
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static const etc2_uint32 ETC2_PKM_HEIGHT_OFFSET = 14;
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static etc2_uint32 readBEUint16(const etc2_byte *pIn) {
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return (pIn[0] << 8) | pIn[1];
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}
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// Check if a PKM header is correctly formatted.
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etc2_bool etc2_pkm_is_valid(const etc2_byte *pHeader) {
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if (memcmp(pHeader, kMagic, sizeof(kMagic))) {
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return false;
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}
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etc2_uint32 format = readBEUint16(pHeader + ETC2_PKM_FORMAT_OFFSET);
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etc2_uint32 encodedWidth = readBEUint16(pHeader + ETC2_PKM_ENCODED_WIDTH_OFFSET);
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etc2_uint32 encodedHeight = readBEUint16(pHeader + ETC2_PKM_ENCODED_HEIGHT_OFFSET);
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etc2_uint32 width = readBEUint16(pHeader + ETC2_PKM_WIDTH_OFFSET);
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etc2_uint32 height = readBEUint16(pHeader + ETC2_PKM_HEIGHT_OFFSET);
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return (format == ETC2_RGB_NO_MIPMAPS || format == ETC2_RGBA_NO_MIPMAPS) &&
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encodedWidth >= width && encodedWidth - width < 4 &&
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encodedHeight >= height && encodedHeight - height < 4;
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}
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// Read the image width from a PKM header
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etc2_uint32 etc2_pkm_get_width(const etc2_byte *pHeader) {
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return readBEUint16(pHeader + ETC2_PKM_WIDTH_OFFSET);
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}
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// Read the image height from a PKM header
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etc2_uint32 etc2_pkm_get_height(const etc2_byte *pHeader) {
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return readBEUint16(pHeader + ETC2_PKM_HEIGHT_OFFSET);
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}
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etc2_uint32 etc2_pkm_get_format(const uint8_t *pHeader) {
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return readBEUint16(pHeader + ETC2_PKM_FORMAT_OFFSET);
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}
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