mirror of https://github.com/axmolengine/axmol.git
79 lines
3.2 KiB
C++
79 lines
3.2 KiB
C++
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/****************************************************************************
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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) 2017-2018 Xiamen Yaji Software Co., Ltd.
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http://www.cocos2d-x.org
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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 documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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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 void writeBEUint16(etc2_byte* pOut, etc2_uint32 data) {
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pOut[0] = (etc2_byte) (data >> 8);
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pOut[1] = (etc2_byte) data;
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}
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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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