115 lines
3.8 KiB
C
115 lines
3.8 KiB
C
// Copyright 2009 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//////////////////////////////////////////////////////////////////////////////////////////
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// This is a fork of the AOSP project ETC1 codec. The original code can be found
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// at the following web site:
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// https://android.googlesource.com/platform/frameworks/native/+/master/opengl/libs/ETC1/
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//////////////////////////////////////////////////////////////////////////////////////////
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#ifndef __etc1_h__
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#define __etc1_h__
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#define ETC1_ENCODED_BLOCK_SIZE 8
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#define ETC1_DECODED_BLOCK_SIZE 48
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#ifndef ETC1_RGB8_OES
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#define ETC1_RGB8_OES 0x8D64
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#endif
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typedef unsigned char etc1_byte;
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typedef int etc1_bool;
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typedef unsigned int etc1_uint32;
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#ifdef __cplusplus
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extern "C" {
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#endif
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// Encode a block of pixels.
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//
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// pIn is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
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// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
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// value of pixel (x, y).
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//
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// validPixelMask is a 16-bit mask where bit (1 << (x + y * 4)) indicates whether
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// the corresponding (x,y) pixel is valid. Invalid pixel color values are ignored when compressing.
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//
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// pOut is an ETC1 compressed version of the data.
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void etc1_encode_block(const etc1_byte* pIn, etc1_uint32 validPixelMask, etc1_byte* pOut);
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// Decode a block of pixels.
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//
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// pIn is an ETC1 compressed version of the data.
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//
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// pOut is a pointer to a ETC_DECODED_BLOCK_SIZE array of bytes that represent a
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// 4 x 4 square of 3-byte pixels in form R, G, B. Byte (3 * (x + 4 * y) is the R
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// value of pixel (x, y).
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void etc1_decode_block(const etc1_byte* pIn, etc1_byte* pOut);
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// Return the size of the encoded image data (does not include size of PKM header).
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etc1_uint32 etc1_get_encoded_data_size(etc1_uint32 width, etc1_uint32 height);
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// Encode an entire image.
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// pIn - pointer to the image data. Formatted such that
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// pixel (x,y) is at pIn + pixelSize * x + stride * y;
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// pOut - pointer to encoded data. Must be large enough to store entire encoded image.
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// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
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// returns non-zero if there is an error.
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int etc1_encode_image(const etc1_byte* pIn, etc1_uint32 width, etc1_uint32 height,
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etc1_uint32 pixelSize, etc1_uint32 stride, etc1_byte* pOut);
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// Decode an entire image.
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// pIn - pointer to encoded data.
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// pOut - pointer to the image data. Will be written such that
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// pixel (x,y) is at pIn + pixelSize * x + stride * y. Must be
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// large enough to store entire image.
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// pixelSize can be 2 or 3. 2 is an GL_UNSIGNED_SHORT_5_6_5 image, 3 is a GL_BYTE RGB image.
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// returns non-zero if there is an error.
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int etc1_decode_image(const etc1_byte* pIn, etc1_byte* pOut,
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etc1_uint32 width, etc1_uint32 height,
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etc1_uint32 pixelSize, etc1_uint32 stride);
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// Size of a PKM header, in bytes.
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#define ETC_PKM_HEADER_SIZE 16
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// Format a PKM header
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void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height);
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// Check if a PKM header is correctly formatted.
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etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader);
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// Read the image width from a PKM header
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etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader);
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// Read the image height from a PKM header
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etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader);
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#ifdef __cplusplus
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}
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#endif
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#endif
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