526 lines
15 KiB
C
526 lines
15 KiB
C
/*
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QOI - The "Quite OK Image" format for fast, lossless image compression
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Dominic Szablewski - https://phoboslab.org
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-- LICENSE: The MIT License(MIT)
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Copyright(c) 2021 Dominic Szablewski
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Permission is hereby granted, free of charge, to any person obtaining a copy of
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this software and associated documentation files(the "Software"), to deal in
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the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
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of the Software, and to permit persons to whom the Software is furnished to do
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so, subject to the following conditions :
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The above copyright notice and this permission notice shall be included in all
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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 THE
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SOFTWARE.
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-- About
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QOI encodes and decodes images in a lossless format. An encoded QOI image is
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usually around 10--30% larger than a decently optimized PNG image.
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QOI outperforms simpler PNG encoders in compression ratio and performance. QOI
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images are typically 20% smaller than PNGs written with stbi_image but 10%
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larger than with libpng. Encoding is 25-50x faster and decoding is 3-4x faster
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than stbi_image or libpng.
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-- Synopsis
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// Define `QOI_IMPLEMENTATION` in *one* C/C++ file before including this
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// library to create the implementation.
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#define QOI_IMPLEMENTATION
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#include "qoi.h"
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// Load and decode a QOI image from the file system into a 32bbp RGBA buffer
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int width, height;
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void *rgba_pixels = qoi_read("image.qoi", &width, &height, 4);
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// Encode and store an RGBA buffer to the file system
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qoi_write("image_new.qoi", rgba_pixels, width, height, 4);
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-- Documentation
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This library provides the following functions;
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- qoi_read -- read and decode a QOI file
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- qoi_decode -- decode the raw bytes of a QOI image from memory
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- qoi_write -- encode and write a QOI file
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- qoi_encode -- encode an rgba buffer into a QOI image in memory
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See the function declaration below for the signature and more information.
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If you don't want/need the qoi_read and qoi_write functions, you can define
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QOI_NO_STDIO before including this library.
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This library uses malloc() and free(). To supply your own malloc implementation
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you can define QOI_MALLOC and QOI_FREE before including this library.
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-- Data Format
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A QOI file has a 12 byte header, followed by any number of data "chunks".
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struct qoi_header_t {
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char magic[4]; // magic bytes "qoif"
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uint32_t width; // image width in pixels (BE)
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uint32_t height; // image height in pixels (BE)
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uint8_t channels; // must be 3 (RGB) or 4 (RGBA)
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uint8_t colorspace; // a bitmap 0000rgba where
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// - a zero bit indicates sRGBA,
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// - a one bit indicates linear (user interpreted)
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// colorspace for each channel
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};
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The decoder and encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous
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pixel value. Pixels are either encoded as
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- a run of the previous pixel
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- an index into a previously seen pixel
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- a difference to the previous pixel value in r,g,b,a
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- full r,g,b,a values
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A running array[64] of previously seen pixel values is maintained by the encoder
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and decoder. Each pixel that is seen by the encoder and decoder is put into this
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array at the position (r^g^b^a) % 64. In the encoder, if the pixel value at this
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index matches the current pixel, this index position is written to the stream.
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Each chunk starts with a 2, 3 or 4 bit tag, followed by a number of data bits.
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The bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned.
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QOI_INDEX {
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u8 tag : 2; // b00
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u8 idx : 6; // 6-bit index into the color index array: 0..63
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}
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QOI_RUN_8 {
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u8 tag : 3; // b010
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u8 run : 5; // 5-bit run-length repeating the previous pixel: 1..32
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}
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QOI_RUN_16 {
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u8 tag : 3; // b011
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u16 run : 13; // 13-bit run-length repeating the previous pixel: 33..8224
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}
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QOI_DIFF_8 {
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u8 tag : 2; // b10
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u8 dr : 2; // 2-bit red channel difference: -2..1
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u8 dg : 2; // 2-bit green channel difference: -2..1
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u8 db : 2; // 2-bit blue channel difference: -2..1
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}
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QOI_DIFF_16 {
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u8 tag : 3; // b110
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u8 dr : 5; // 5-bit red channel difference: -16..15
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u8 dg : 4; // 4-bit green channel difference: -8.. 7
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u8 db : 4; // 4-bit blue channel difference: -8.. 7
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}
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QOI_DIFF_24 {
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u8 tag : 4; // b1110
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u8 dr : 5; // 5-bit red channel difference: -16..15
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u8 dg : 5; // 5-bit green channel difference: -16..15
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u8 db : 5; // 5-bit blue channel difference: -16..15
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u8 da : 5; // 5-bit alpha channel difference: -16..15
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}
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QOI_COLOR {
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u8 tag : 4; // b1111
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u8 has_r: 1; // red byte follows
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u8 has_g: 1; // green byte follows
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u8 has_b: 1; // blue byte follows
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u8 has_a: 1; // alpha byte follows
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u8 r; // red value if has_r == 1: 0..255
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u8 g; // green value if has_g == 1: 0..255
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u8 b; // blue value if has_b == 1: 0..255
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u8 a; // alpha value if has_a == 1: 0..255
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}
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The byte stream is padded with 4 zero bytes. Size the longest chunk we can
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encounter is 5 bytes (QOI_COLOR with RGBA set), with this padding we just have
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to check for an overrun once per decode loop iteration.
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*/
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// -----------------------------------------------------------------------------
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// Header - Public functions
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#ifndef QOI_H
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#define QOI_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef QOI_NO_STDIO
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// Encode raw RGB or RGBA pixels into a QOI image write it to the file system.
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// w and h denote the the width and height of the pixel data. channels must be
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// either 3 for RGB data or 4 for RGBA.
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// The function returns 0 on failure (invalid parameters, or fopen or malloc
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// failed) or the number of bytes written on success.
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int qoi_write(const char *filename, const void *data, int w, int h, int channels);
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// Read and decode a QOI image from the file system into either raw RGB
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// (channels=3) or RGBA (channels=4) pixel data.
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// The function either returns NULL on failure (invalid data, or malloc or fopen
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// failed) or a pointer to the decoded pixels. On success out_w and out_h will
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// be set to the width and height of the decoded image.
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// The returned pixel data should be free()d after use.
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void *qoi_read(const char *filename, int *out_w, int *out_h, int channels);
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#endif // QOI_NO_STDIO
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// Encode raw RGB or RGBA pixels into a QOI image in memory. w and h denote the
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// width and height of the pixel data. channels must be either 3 for RGB data
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// or 4 for RGBA.
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// The function either returns NULL on failure (invalid parameters or malloc
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// failed) or a pointer to the encoded data on success. On success the out_len
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// is set to the size in bytes of the encoded data.
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// The returned qoi data should be free()d after user.
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void *qoi_encode(const void *data, int w, int h, int channels, int *out_len);
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// Decode a QOI image from memory into either raw RGB (channels=3) or RGBA
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// (channels=4) pixel data.
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// The function either returns NULL on failure (invalid parameters or malloc
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// failed) or a pointer to the decoded pixels. On success out_w and out_h will
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// be set to the width and height of the decoded image.
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// The returned pixel data should be free()d after use.
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void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channels);
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#ifdef __cplusplus
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}
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#endif
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#endif // QOI_H
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// -----------------------------------------------------------------------------
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// Implementation
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#ifdef QOI_IMPLEMENTATION
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#include <stdlib.h>
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#ifndef QOI_MALLOC
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#define QOI_MALLOC(sz) malloc(sz)
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#define QOI_FREE(p) free(p)
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#endif
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#define QOI_INDEX 0x00 // 00xxxxxx
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#define QOI_RUN_8 0x40 // 010xxxxx
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#define QOI_RUN_16 0x60 // 011xxxxx
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#define QOI_DIFF_8 0x80 // 10xxxxxx
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#define QOI_DIFF_16 0xc0 // 110xxxxx
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#define QOI_DIFF_24 0xe0 // 1110xxxx
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#define QOI_COLOR 0xf0 // 1111xxxx
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#define QOI_MASK_2 0xc0 // 11000000
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#define QOI_MASK_3 0xe0 // 11100000
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#define QOI_MASK_4 0xf0 // 11110000
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#define QOI_COLOR_HASH(C) (C.rgba.r ^ C.rgba.g ^ C.rgba.b ^ C.rgba.a)
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#define QOI_MAGIC \
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(((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \
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((unsigned int)'i') << 8 | ((unsigned int)'f'))
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#define QOI_HEADER_SIZE 12
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#define QOI_PADDING 4
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typedef union {
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struct { unsigned char r, g, b, a; } rgba;
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unsigned int v;
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} qoi_rgba_t;
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void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
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bytes[(*p)++] = (0xff000000 & v) >> 24;
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bytes[(*p)++] = (0x00ff0000 & v) >> 16;
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bytes[(*p)++] = (0x0000ff00 & v) >> 8;
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bytes[(*p)++] = (0x000000ff & v);
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}
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unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
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unsigned int a = bytes[(*p)++];
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unsigned int b = bytes[(*p)++];
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unsigned int c = bytes[(*p)++];
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unsigned int d = bytes[(*p)++];
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return (a << 24) | (b << 16) | (c << 8) | d;
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}
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void *qoi_encode(const void *data, int w, int h, int channels, int *out_len) {
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if (
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data == NULL || out_len == NULL ||
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w <= 0 || w >= (1 << 16) ||
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h <= 0 || h >= (1 << 16) ||
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channels < 3 || channels > 4
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) {
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return NULL;
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}
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int max_size = w * h * (channels + 1) + QOI_HEADER_SIZE + QOI_PADDING;
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int p = 0;
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unsigned char *bytes = QOI_MALLOC(max_size);
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if (!bytes) {
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return NULL;
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}
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qoi_write_32(bytes, &p, QOI_MAGIC);
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qoi_write_32(bytes, &p, w);
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qoi_write_32(bytes, &p, h);
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bytes[p++] = channels;
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bytes[p++] = 0; // TODO: accept a colorspace as a parameter to this function
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const unsigned char *pixels = (const unsigned char *)data;
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qoi_rgba_t index[64] = {0};
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int run = 0;
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qoi_rgba_t px_prev = {.rgba = {.r = 0, .g = 0, .b = 0, .a = 255}};
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qoi_rgba_t px = px_prev;
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int px_len = w * h * channels;
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int px_end = px_len - channels;
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for (int px_pos = 0; px_pos < px_len; px_pos += channels) {
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if (channels == 4) {
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px = *(qoi_rgba_t *)(pixels + px_pos);
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}
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else {
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px.rgba.r = pixels[px_pos];
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px.rgba.g = pixels[px_pos+1];
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px.rgba.b = pixels[px_pos+2];
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}
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if (px.v == px_prev.v) {
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run++;
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}
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if (run > 0 && (run == 0x2020 || px.v != px_prev.v || px_pos == px_end)) {
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if (run < 33) {
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run -= 1;
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bytes[p++] = QOI_RUN_8 | run;
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}
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else {
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run -= 33;
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bytes[p++] = QOI_RUN_16 | run >> 8;
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bytes[p++] = run;
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}
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run = 0;
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}
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if (px.v != px_prev.v) {
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int index_pos = QOI_COLOR_HASH(px) % 64;
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if (index[index_pos].v == px.v) {
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bytes[p++] = QOI_INDEX | index_pos;
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}
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else {
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index[index_pos] = px;
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int vr = px.rgba.r - px_prev.rgba.r;
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int vg = px.rgba.g - px_prev.rgba.g;
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int vb = px.rgba.b - px_prev.rgba.b;
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int va = px.rgba.a - px_prev.rgba.a;
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if (
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vr > -17 && vr < 16 && vg > -17 && vg < 16 &&
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vb > -17 && vb < 16 && va > -17 && va < 16
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) {
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if (
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va == 0 && vr > -3 && vr < 2 &&
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vg > -3 && vg < 2 && vb > -3 && vb < 2
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) {
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bytes[p++] = QOI_DIFF_8 | ((vr + 2) << 4) | (vg + 2) << 2 | (vb + 2);
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}
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else if (
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va == 0 && vr > -17 && vr < 16 &&
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vg > -9 && vg < 8 && vb > -9 && vb < 8
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) {
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bytes[p++] = QOI_DIFF_16 | (vr + 16);
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bytes[p++] = ((vg + 8) << 4) | (vb + 8);
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}
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else {
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bytes[p++] = QOI_DIFF_24 | ((vr + 16) >> 1);
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bytes[p++] = ((vr + 16) << 7) | ((vg + 16) << 2) | ((vb + 16) >> 3);
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bytes[p++] = ((vb + 16) << 5) | (va + 16);
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}
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}
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else {
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bytes[p++] = QOI_COLOR | (vr?8:0)|(vg?4:0)|(vb?2:0)|(va?1:0);
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if (vr) { bytes[p++] = px.rgba.r; }
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if (vg) { bytes[p++] = px.rgba.g; }
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if (vb) { bytes[p++] = px.rgba.b; }
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if (va) { bytes[p++] = px.rgba.a; }
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}
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}
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}
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px_prev = px;
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}
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for (int i = 0; i < QOI_PADDING; i++) {
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bytes[p++] = 0;
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}
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*out_len = p;
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return bytes;
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}
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void *qoi_decode(const void *data, int size, int *out_w, int *out_h, int channels) {
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if (channels < 3 || channels > 4 || size < QOI_HEADER_SIZE + QOI_PADDING) {
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return NULL;
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}
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const unsigned char *bytes = (const unsigned char *)data;
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int p = 0;
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unsigned int header_magic = qoi_read_32(bytes, &p);
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unsigned int header_w = qoi_read_32(bytes, &p);
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unsigned int header_h = qoi_read_32(bytes, &p);
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unsigned int header_channels = bytes[p++];
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unsigned int header_colorspace = bytes[p++];
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if (
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header_w == 0 || header_h == 0 ||
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header_channels < 3 || header_channels > 4 ||
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header_magic != QOI_MAGIC
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) {
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return NULL;
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}
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int px_len = header_w * header_h * channels;
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unsigned char *pixels = QOI_MALLOC(px_len);
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if (!pixels) {
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return NULL;
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}
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qoi_rgba_t px = {.rgba = {.r = 0, .g = 0, .b = 0, .a = 255}};
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qoi_rgba_t index[64] = {0};
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int run = 0;
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int chunks_len = size - QOI_PADDING;
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for (int px_pos = 0; px_pos < px_len; px_pos += channels) {
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if (run > 0) {
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run--;
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}
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else if (p < chunks_len) {
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int b1 = bytes[p++];
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if ((b1 & QOI_MASK_2) == QOI_INDEX) {
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px = index[b1 ^ QOI_INDEX];
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}
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else if ((b1 & QOI_MASK_3) == QOI_RUN_8) {
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run = (b1 & 0x1f);
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}
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else if ((b1 & QOI_MASK_3) == QOI_RUN_16) {
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int b2 = bytes[p++];
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run = (((b1 & 0x1f) << 8) | (b2)) + 32;
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}
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else if ((b1 & QOI_MASK_2) == QOI_DIFF_8) {
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px.rgba.r += ((b1 >> 4) & 0x03) - 2;
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px.rgba.g += ((b1 >> 2) & 0x03) - 2;
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px.rgba.b += ( b1 & 0x03) - 2;
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}
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else if ((b1 & QOI_MASK_3) == QOI_DIFF_16) {
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int b2 = bytes[p++];
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px.rgba.r += (b1 & 0x1f) - 16;
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px.rgba.g += (b2 >> 4) - 8;
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px.rgba.b += (b2 & 0x0f) - 8;
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}
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else if ((b1 & QOI_MASK_4) == QOI_DIFF_24) {
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int b2 = bytes[p++];
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int b3 = bytes[p++];
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px.rgba.r += (((b1 & 0x0f) << 1) | (b2 >> 7)) - 16;
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px.rgba.g += ((b2 & 0x7c) >> 2) - 16;
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px.rgba.b += (((b2 & 0x03) << 3) | ((b3 & 0xe0) >> 5)) - 16;
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px.rgba.a += (b3 & 0x1f) - 16;
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}
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else if ((b1 & QOI_MASK_4) == QOI_COLOR) {
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if (b1 & 8) { px.rgba.r = bytes[p++]; }
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if (b1 & 4) { px.rgba.g = bytes[p++]; }
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if (b1 & 2) { px.rgba.b = bytes[p++]; }
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if (b1 & 1) { px.rgba.a = bytes[p++]; }
|
|
}
|
|
|
|
index[QOI_COLOR_HASH(px) % 64] = px;
|
|
}
|
|
|
|
if (channels == 4) {
|
|
*(qoi_rgba_t*)(pixels + px_pos) = px;
|
|
}
|
|
else {
|
|
pixels[px_pos] = px.rgba.r;
|
|
pixels[px_pos+1] = px.rgba.g;
|
|
pixels[px_pos+2] = px.rgba.b;
|
|
}
|
|
}
|
|
|
|
*out_w = header_w;
|
|
*out_h = header_h;
|
|
return pixels;
|
|
}
|
|
|
|
#ifndef QOI_NO_STDIO
|
|
#include <stdio.h>
|
|
|
|
int qoi_write(const char *filename, const void *data, int w, int h, int channels) {
|
|
int size;
|
|
void *encoded = qoi_encode(data, w, h, channels, &size);
|
|
if (!encoded) {
|
|
return 0;
|
|
}
|
|
|
|
FILE *f = fopen(filename, "wb");
|
|
if (!f) {
|
|
QOI_FREE(encoded);
|
|
return 0;
|
|
}
|
|
|
|
fwrite(encoded, 1, size, f);
|
|
fclose(f);
|
|
QOI_FREE(encoded);
|
|
return size;
|
|
}
|
|
|
|
void *qoi_read(const char *filename, int *out_w, int *out_h, int channels) {
|
|
FILE *f = fopen(filename, "rb");
|
|
if (!f) {
|
|
return NULL;
|
|
}
|
|
|
|
fseek(f, 0, SEEK_END);
|
|
int size = ftell(f);
|
|
fseek(f, 0, SEEK_SET);
|
|
|
|
void *data = QOI_MALLOC(size);
|
|
if (!data) {
|
|
return NULL;
|
|
}
|
|
|
|
int bytes_read = fread(data, 1, size, f);
|
|
fclose(f);
|
|
|
|
void *pixels = qoi_decode(data, bytes_read, out_w, out_h, channels);
|
|
QOI_FREE(data);
|
|
return pixels;
|
|
}
|
|
|
|
#endif // QOI_NO_STDIO
|
|
#endif // QOI_IMPLEMENTATION
|