Added Qoi image loader. Resolves #2.

.gitignore

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+.bmx
+.DS_Store
+
+*.a
+*.i
+*.i2

qoi.mod/common.bmx

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+' Copyright (c) 2021 Bruce A Henderson
+' 
+' Permission is hereby granted, free of charge, to any person obtaining a copy
+' of this software and associated documentation files (the "Software"), to deal
+' in the Software without restriction, including without limitation the rights
+' to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+' copies of the Software, and to permit persons to whom the Software is
+' furnished to do so, subject to the following conditions:
+' 
+' The above copyright notice and this permission notice shall be included in
+' all copies or substantial portions of the Software.
+' 
+' THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+' IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+' FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+' AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+' LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+' OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+' THE SOFTWARE.
+'
+SuperStrict
+
+Import "qoi/*.h"
+Import "glue.c"
+
+
+Extern
+	Function qoi_decode:Byte Ptr(data:byte Ptr, size:Int, desc:SQoiDesc Var, channels:Int)
+	Function qoi_encode:Byte Ptr(data:Byte Ptr, desc:SQoiDesc Var, outLen:Int Var)
+End Extern
+
+
+Rem
+bbdoc: Describes the format of the Qoi image.
+End Rem
+Struct SQoiDesc
+	Field width:UInt
+	Field height:UInt
+	Field channels:Byte
+	Field colorspace:EQoiColorspace
+End Struct
+
+Enum EQoiColorspace : Byte
+	SRGB
+	LINEAR
+End Enum

qoi.mod/examples/example_01.bmx

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+SuperStrict
+
+?win32
+Framework SDL.d3d9sdlmax2d
+?Not win32
+Framework SDL.gl2sdlmax2d
+?
+Import Image.Qoi
+Import BRL.Standardio
+
+Local pix:TPixmap = LoadPixmap("kodim23.qoi")
+
+If pix Then
+	Print pix.width + ", " + pix.height
+Else
+	Print "Unable to load file"
+	End
+End If
+
+Graphics 1024, 768, 0
+
+Local img:TImage = LoadImage( pix )
+
+While Not KeyDown(KEY_ESCAPE)
+	Cls
+
+	if img Then
+		DrawImage img, 0, 0
+	End If
+
+
+	Flip
+Wend

qoi.mod/glue.c

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+/*
+ Copyright (c) 2021 Bruce A Henderson
+ 
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be included in
+ all copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ THE SOFTWARE.
+*/
+
+#define QOI_IMPLEMENTATION
+#define QOI_NO_STDIO
+#include "qoi.h"
+

qoi.mod/qoi.bmx

@@ -0,0 +1,131 @@
+' Copyright (c) 2021 Bruce A Henderson
+' 
+' Permission is hereby granted, free of charge, to any person obtaining a copy
+' of this software and associated documentation files (the "Software"), to deal
+' in the Software without restriction, including without limitation the rights
+' to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+' copies of the Software, and to permit persons to whom the Software is
+' furnished to do so, subject to the following conditions:
+' 
+' The above copyright notice and this permission notice shall be included in
+' all copies or substantial portions of the Software.
+' 
+' THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+' IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+' FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+' AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+' LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+' OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+' THE SOFTWARE.
+'
+SuperStrict
+
+Rem
+bbdoc: Qoi Image Loading/Saving
+End Rem
+Module Image.Qoi
+
+ModuleInfo "Version: 1.00"
+ModuleInfo "License: MIT"
+ModuleInfo "Copyright: Wrapper - 2021 Bruce A Henderson"
+
+ModuleInfo "History: 1.00"
+ModuleInfo "History: Initial Release."
+
+Import BRL.Pixmap
+Import Pub.StdC
+
+Import "common.bmx"
+
+Rem
+bbdoc: Qoi image format files.
+about: See https://qoiformat.org/ for more information.
+End Rem
+Type TQoiImage
+
+	Rem
+	bbdoc: Loads Qoi image from a file as a #TPixmap.
+	End Rem
+	Function Load:TPixmap(file:String, channels:Int = 0)
+		Local stream:TStream = ReadStream(file)
+		If stream Then
+			Local pix:TPixmap = Load(stream, channels)
+			stream.Close()
+			Return pix
+		End If
+	End Function
+
+	Rem
+	bbdoc: Loads Qoi image from stream as a #TPixmap.
+	End Rem
+	Function Load:TPixmap(stream:TStream, channels:Int = 0)
+
+		Local desc:SQoiDesc
+		Local data:Byte[] = LoadByteArray(stream)
+		
+		Local pixels:Byte Ptr = qoi_decode(data, data.Length, desc, channels)
+		If pixels Then
+
+			Local format:Int = PF_RGB888
+			Local align:Int = 3
+			If desc.channels = 4 Then
+				format = PF_RGBA8888
+				align = 4
+			End If
+			Local pix:TPixmap = TPixmap.Create(desc.width, desc.height, format, align)
+			
+			MemCopy(pix.pixels, pixels, Size_T(desc.width * desc.height * desc.channels))
+
+			free_(pixels)
+			Return pix
+		End If
+
+	End Function
+
+	Rem
+	bbdoc: Saves pixmap to a #TStream as Qoi image.
+	End Rem
+	Function Save(stream:TStream, pix:TPixmap)
+		Local desc:SQoiDesc
+		desc.width = pix.width
+		desc.height = pix.height
+		desc.colorspace = EQoiColorspace.LINEAR
+
+		If pix.format <> PF_RGB888 And pix.format <> PF_RGBA8888 Then
+			pix = pix.Convert(PF_STDFORMAT)
+		End If
+
+		Select pix.format
+			Case PF_RGB888
+				desc.channels = 3
+			Case PF_RGBA8888
+				desc.channels = 4
+		End Select
+
+		Local data:Byte Ptr
+		Try
+			Local outLen:Int
+			data = qoi_encode(pix.pixels, desc, outLen)
+			stream.WriteBytes(data, outLen)
+		Finally
+			If data Then
+				free_(data)
+			End If
+		End Try
+		
+	End Function
+End Type
+
+Private
+
+Type TPixmapLoaderQoi Extends TPixmapLoader
+
+	Method LoadPixmap:TPixmap( stream:TStream ) Override
+
+		Return TQoiImage.Load(stream)
+
+	End Method
+
+End Type
+
+New TPixmapLoaderQoi

qoi.mod/qoi/.gitignore

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+images/
+stb_image.h
+stb_image_write.h
+qoibench
+qoiconv

qoi.mod/qoi/README.md

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+![QOI Logo](https://qoiformat.org/qoi-logo.svg)
+
+# QOI - The “Quite OK Image Format” for fast, lossless image compression
+
+Single-file MIT licensed library for C/C++
+
+See [qoi.h](https://github.com/phoboslab/qoi/blob/master/qoi.h) for
+the documentation and format specification.
+
+More info at https://qoiformat.org
+
+
+## Why?
+
+Compared to stb_image and stb_image_write QOI offers 20x-50x faster encoding,
+3x-4x faster decoding and 20% better compression. It's also stupidly simple and
+fits in about 300 lines of C.
+
+
+## Example Usage
+
+- [qoiconv.c](https://github.com/phoboslab/qoi/blob/master/qoiconv.c)
+converts between png <> qoi
+ - [qoibench.c](https://github.com/phoboslab/qoi/blob/master/qoibench.c)
+a simple wrapper to benchmark stbi, libpng and qoi
+
+
+## Limitations
+
+The QOI file format allows for huge images with up to 18 exa-pixels. A streaming 
+en-/decoder can handle these with minimal RAM requirements, assuming there is 
+enough storage space.
+
+This particular implementation of QOI however is limited to images with a 
+maximum size of 400 million pixels. It will safely refuse to en-/decode anything
+larger than that. This is not a streaming en-/decoder. It loads the whole image
+file into RAM before doing any work and is not extensively optimized for 
+performance (but it's still very fast).
+
+If this is a limitation for your use case, please look into any of the other 
+implementations listed below.
+
+
+## Tools
+
+- https://github.com/floooh/qoiview - native QOI viewer
+- https://github.com/pfusik/qoi-ci/releases/tag/qoi-ci-1.1.0 - QOI Plugin installer for GIMP, Imagine, Paint.NET and XnView MP
+- https://github.com/iOrange/QoiFileTypeNet/releases/tag/v0.2 - QOI Plugin for Paint.NET
+- https://github.com/iOrange/QOIThumbnailProvider - Add thumbnails for QOI images in Windows Explorer
+- https://github.com/Tom94/tev - another native QOI viewer (allows pixel peeping and comparison with other image formats)
+
+
+## Implementations & Bindings of QOI
+
+- https://github.com/pfusik/qoi-ci (Ć, transpiled to C, C++, C#, Java, JavaScript, Python and Swift)
+- https://github.com/kodonnell/qoi (Python)
+- https://github.com/Cr4xy/lua-qoi (Lua)
+- https://github.com/superzazu/SDL_QOI (C, SDL2 bindings)
+- https://github.com/saharNooby/qoi-java (Java)
+- https://github.com/MasterQ32/zig-qoi (Zig)
+- https://github.com/rbino/qoix (Elixir)
+- https://github.com/NUlliiON/QoiSharp (C#)
+- https://github.com/zakarumych/rapid-qoi (Rust)
+- https://github.com/takeyourhatoff/qoi (Go)
+- https://github.com/DosWorld/pasqoi (Pascal)
+- https://github.com/elihwyma/Swift-QOI (Swift)
+- https://github.com/xfmoulet/qoi (Go)
+- https://erratique.ch/software/qoic (OCaml)
+
+
+## QOI Support in Other Software
+
+- [SerenityOS](https://github.com/SerenityOS/serenity) supports decoding QOI system wide through a custom [cpp implementation in LibGfx](https://github.com/SerenityOS/serenity/blob/master/Userland/Libraries/LibGfx/QOILoader.h)
+- [Raylib](https://github.com/raysan5/raylib) supports decoding and encoding QOI textures through its [rtextures module](https://github.com/raysan5/raylib/blob/master/src/rtextures.c)
+- [Rebol3](https://github.com/Oldes/Rebol3/issues/39) supports decoding and encoding QOI using a native codec
+- [c-ray](https://github.com/vkoskiv/c-ray) supports QOI natively
+
+
+## Packages
+
+[AUR](https://aur.archlinux.org/pkgbase/qoi-git/) - system-wide qoi.h, qoiconv and qoibench install as split packages.
+
+
+## Implementations not yet conforming to the final specification
+
+These implementations are based on the pre-release version of QOI. Resulting files are not compatible with the current version.
+
+- https://github.com/steven-joruk/qoi (Rust)
+- https://github.com/ChevyRay/qoi_rs (Rust)
+- https://github.com/panzi/jsqoi (TypeScript)
+- https://github.com/0xd34df00d/hsqoi (Haskell)
+

qoi.mod/qoi/qoi.h

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+/*
+
+QOI - The "Quite OK Image" format for fast, lossless image compression
+
+Dominic Szablewski - https://phoboslab.org
+
+
+-- LICENSE: The MIT License(MIT)
+
+Copyright(c) 2021 Dominic Szablewski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files(the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions :
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+
+-- About
+
+QOI encodes and decodes images in a lossless format. Compared to stb_image and
+stb_image_write QOI offers 20x-50x faster encoding, 3x-4x faster decoding and
+20% better compression.
+
+
+-- Synopsis
+
+// Define `QOI_IMPLEMENTATION` in *one* C/C++ file before including this
+// library to create the implementation.
+
+#define QOI_IMPLEMENTATION
+#include "qoi.h"
+
+// Encode and store an RGBA buffer to the file system. The qoi_desc describes
+// the input pixel data.
+qoi_write("image_new.qoi", rgba_pixels, &(qoi_desc){
+	.width = 1920,
+	.height = 1080,
+	.channels = 4,
+	.colorspace = QOI_SRGB
+});
+
+// Load and decode a QOI image from the file system into a 32bbp RGBA buffer.
+// The qoi_desc struct will be filled with the width, height, number of channels
+// and colorspace read from the file header.
+qoi_desc desc;
+void *rgba_pixels = qoi_read("image.qoi", &desc, 4);
+
+
+
+-- Documentation
+
+This library provides the following functions;
+- qoi_read    -- read and decode a QOI file
+- qoi_decode  -- decode the raw bytes of a QOI image from memory
+- qoi_write   -- encode and write a QOI file
+- qoi_encode  -- encode an rgba buffer into a QOI image in memory
+
+See the function declaration below for the signature and more information.
+
+If you don't want/need the qoi_read and qoi_write functions, you can define
+QOI_NO_STDIO before including this library.
+
+This library uses malloc() and free(). To supply your own malloc implementation
+you can define QOI_MALLOC and QOI_FREE before including this library.
+
+This library uses memset() to zero-initialize the index. To supply your own
+implementation you can define QOI_ZEROARR before including this library.
+
+
+-- Data Format
+
+A QOI file has a 14 byte header, followed by any number of data "chunks" and an
+8-byte end marker.
+
+struct qoi_header_t {
+	char     magic[4];   // magic bytes "qoif"
+	uint32_t width;      // image width in pixels (BE)
+	uint32_t height;     // image height in pixels (BE)
+	uint8_t  channels;   // 3 = RGB, 4 = RGBA
+	uint8_t  colorspace; // 0 = sRGB with linear alpha, 1 = all channels linear
+};
+
+Images are encoded row by row, left to right, top to bottom. The decoder and
+encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous pixel value. An
+image is complete when all pixels specified by width * height have been covered.
+
+Pixels are encoded as
+ - a run of the previous pixel
+ - an index into an array of previously seen pixels
+ - a difference to the previous pixel value in r,g,b
+ - full r,g,b or r,g,b,a values
+
+The color channels are assumed to not be premultiplied with the alpha channel
+("un-premultiplied alpha").
+
+A running array[64] (zero-initialized) of previously seen pixel values is
+maintained by the encoder and decoder. Each pixel that is seen by the encoder
+and decoder is put into this array at the position formed by a hash function of
+the color value. In the encoder, if the pixel value at the index matches the
+current pixel, this index position is written to the stream as QOI_OP_INDEX.
+The hash function for the index is:
+
+	index_position = (r * 3 + g * 5 + b * 7 + a * 11) % 64
+
+Each chunk starts with a 2- or 8-bit tag, followed by a number of data bits. The
+bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned. All
+values encoded in these data bits have the most significant bit on the left.
+
+The 8-bit tags have precedence over the 2-bit tags. A decoder must check for the
+presence of an 8-bit tag first.
+
+The byte stream's end is marked with 7 0x00 bytes followed a single 0x01 byte.
+
+
+The possible chunks are:
+
+
+.- QOI_OP_INDEX ----------.
+|         Byte[0]         |
+|  7  6  5  4  3  2  1  0 |
+|-------+-----------------|
+|  0  0 |     index       |
+`-------------------------`
+2-bit tag b00
+6-bit index into the color index array: 0..63
+
+A valid encoder must not issue 7 or more consecutive QOI_OP_INDEX chunks to the
+index 0, to avoid confusion with the 8 byte end marker.
+
+
+.- QOI_OP_DIFF -----------.
+|         Byte[0]         |
+|  7  6  5  4  3  2  1  0 |
+|-------+-----+-----+-----|
+|  0  1 |  dr |  dg |  db |
+`-------------------------`
+2-bit tag b01
+2-bit   red channel difference from the previous pixel between -2..1
+2-bit green channel difference from the previous pixel between -2..1
+2-bit  blue channel difference from the previous pixel between -2..1
+
+The difference to the current channel values are using a wraparound operation,
+so "1 - 2" will result in 255, while "255 + 1" will result in 0.
+
+Values are stored as unsigned integers with a bias of 2. E.g. -2 is stored as
+0 (b00). 1 is stored as 3 (b11).
+
+The alpha value remains unchanged from the previous pixel.
+
+
+.- QOI_OP_LUMA -------------------------------------.
+|         Byte[0]         |         Byte[1]         |
+|  7  6  5  4  3  2  1  0 |  7  6  5  4  3  2  1  0 |
+|-------+-----------------+-------------+-----------|
+|  1  0 |  green diff     |   dr - dg   |  db - dg  |
+`---------------------------------------------------`
+2-bit tag b10
+6-bit green channel difference from the previous pixel -32..31
+4-bit   red channel difference minus green channel difference -8..7
+4-bit  blue channel difference minus green channel difference -8..7
+
+The green channel is used to indicate the general direction of change and is
+encoded in 6 bits. The red and blue channels (dr and db) base their diffs off
+of the green channel difference and are encoded in 4 bits. I.e.:
+	dr_dg = (last_px.r - cur_px.r) - (last_px.g - cur_px.g)
+	db_dg = (last_px.b - cur_px.b) - (last_px.g - cur_px.g)
+
+The difference to the current channel values are using a wraparound operation,
+so "10 - 13" will result in 253, while "250 + 7" will result in 1.
+
+Values are stored as unsigned integers with a bias of 32 for the green channel
+and a bias of 8 for the red and blue channel.
+
+The alpha value remains unchanged from the previous pixel.
+
+
+.- QOI_OP_RUN ------------.
+|         Byte[0]         |
+|  7  6  5  4  3  2  1  0 |
+|-------+-----------------|
+|  1  1 |       run       |
+`-------------------------`
+2-bit tag b11
+6-bit run-length repeating the previous pixel: 1..62
+
+The run-length is stored with a bias of -1. Note that the run-lengths 63 and 64
+(b111110 and b111111) are illegal as they are occupied by the QOI_OP_RGB and
+QOI_OP_RGBA tags.
+
+
+.- QOI_OP_RGB ------------------------------------------.
+|         Byte[0]         | Byte[1] | Byte[2] | Byte[3] |
+|  7  6  5  4  3  2  1  0 | 7 .. 0  | 7 .. 0  | 7 .. 0  |
+|-------------------------+---------+---------+---------|
+|  1  1  1  1  1  1  1  0 |   red   |  green  |  blue   |
+`-------------------------------------------------------`
+8-bit tag b11111110
+8-bit   red channel value
+8-bit green channel value
+8-bit  blue channel value
+
+The alpha value remains unchanged from the previous pixel.
+
+
+.- QOI_OP_RGBA ---------------------------------------------------.
+|         Byte[0]         | Byte[1] | Byte[2] | Byte[3] | Byte[4] |
+|  7  6  5  4  3  2  1  0 | 7 .. 0  | 7 .. 0  | 7 .. 0  | 7 .. 0  |
+|-------------------------+---------+---------+---------+---------|
+|  1  1  1  1  1  1  1  1 |   red   |  green  |  blue   |  alpha  |
+`-----------------------------------------------------------------`
+8-bit tag b11111111
+8-bit   red channel value
+8-bit green channel value
+8-bit  blue channel value
+8-bit alpha channel value
+
+*/
+
+
+/* -----------------------------------------------------------------------------
+Header - Public functions */
+
+#ifndef QOI_H
+#define QOI_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* A pointer to a qoi_desc struct has to be supplied to all of qoi's functions.
+It describes either the input format (for qoi_write and qoi_encode), or is
+filled with the description read from the file header (for qoi_read and
+qoi_decode).
+
+The colorspace in this qoi_desc is an enum where
+	0 = sRGB, i.e. gamma scaled RGB channels and a linear alpha channel
+	1 = all channels are linear
+You may use the constants QOI_SRGB or QOI_LINEAR. The colorspace is purely
+informative. It will be saved to the file header, but does not affect
+en-/decoding in any way. */
+
+#define QOI_SRGB   0
+#define QOI_LINEAR 1
+
+typedef struct {
+	unsigned int width;
+	unsigned int height;
+	unsigned char channels;
+	unsigned char colorspace;
+} qoi_desc;
+
+#ifndef QOI_NO_STDIO
+
+/* Encode raw RGB or RGBA pixels into a QOI image and write it to the file
+system. The qoi_desc struct must be filled with the image width, height,
+number of channels (3 = RGB, 4 = RGBA) and the colorspace.
+
+The function returns 0 on failure (invalid parameters, or fopen or malloc
+failed) or the number of bytes written on success. */
+
+int qoi_write(const char *filename, const void *data, const qoi_desc *desc);
+
+
+/* Read and decode a QOI image from the file system. If channels is 0, the
+number of channels from the file header is used. If channels is 3 or 4 the
+output format will be forced into this number of channels.
+
+The function either returns NULL on failure (invalid data, or malloc or fopen
+failed) or a pointer to the decoded pixels. On success, the qoi_desc struct
+will be filled with the description from the file header.
+
+The returned pixel data should be free()d after use. */
+
+void *qoi_read(const char *filename, qoi_desc *desc, int channels);
+
+#endif /* QOI_NO_STDIO */
+
+
+/* Encode raw RGB or RGBA pixels into a QOI image in memory.
+
+The function either returns NULL on failure (invalid parameters or malloc
+failed) or a pointer to the encoded data on success. On success the out_len
+is set to the size in bytes of the encoded data.
+
+The returned qoi data should be free()d after use. */
+
+void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len);
+
+
+/* Decode a QOI image from memory.
+
+The function either returns NULL on failure (invalid parameters or malloc
+failed) or a pointer to the decoded pixels. On success, the qoi_desc struct
+is filled with the description from the file header.
+
+The returned pixel data should be free()d after use. */
+
+void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels);
+
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* QOI_H */
+
+
+/* -----------------------------------------------------------------------------
+Implementation */
+
+#ifdef QOI_IMPLEMENTATION
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef QOI_MALLOC
+	#define QOI_MALLOC(sz) malloc(sz)
+	#define QOI_FREE(p)    free(p)
+#endif
+#ifndef QOI_ZEROARR
+	#define QOI_ZEROARR(a) memset((a),0,sizeof(a))
+#endif
+
+#define QOI_OP_INDEX  0x00 /* 00xxxxxx */
+#define QOI_OP_DIFF   0x40 /* 01xxxxxx */
+#define QOI_OP_LUMA   0x80 /* 10xxxxxx */
+#define QOI_OP_RUN    0xc0 /* 11xxxxxx */
+#define QOI_OP_RGB    0xfe /* 11111110 */
+#define QOI_OP_RGBA   0xff /* 11111111 */
+
+#define QOI_MASK_2    0xc0 /* 11000000 */
+
+#define QOI_COLOR_HASH(C) (C.rgba.r*3 + C.rgba.g*5 + C.rgba.b*7 + C.rgba.a*11)
+#define QOI_MAGIC \
+	(((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \
+	 ((unsigned int)'i') <<  8 | ((unsigned int)'f'))
+#define QOI_HEADER_SIZE 14
+
+/* 2GB is the max file size that this implementation can safely handle. We guard
+against anything larger than that, assuming the worst case with 5 bytes per
+pixel, rounded down to a nice clean value. 400 million pixels ought to be
+enough for anybody. */
+#define QOI_PIXELS_MAX ((unsigned int)400000000)
+
+typedef union {
+	struct { unsigned char r, g, b, a; } rgba;
+	unsigned int v;
+} qoi_rgba_t;
+
+static const unsigned char qoi_padding[8] = {0,0,0,0,0,0,0,1};
+
+static void qoi_write_32(unsigned char *bytes, int *p, unsigned int v) {
+	bytes[(*p)++] = (0xff000000 & v) >> 24;
+	bytes[(*p)++] = (0x00ff0000 & v) >> 16;
+	bytes[(*p)++] = (0x0000ff00 & v) >> 8;
+	bytes[(*p)++] = (0x000000ff & v);
+}
+
+static unsigned int qoi_read_32(const unsigned char *bytes, int *p) {
+	unsigned int a = bytes[(*p)++];
+	unsigned int b = bytes[(*p)++];
+	unsigned int c = bytes[(*p)++];
+	unsigned int d = bytes[(*p)++];
+	return a << 24 | b << 16 | c << 8 | d;
+}
+
+void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
+	int i, max_size, p, run;
+	int px_len, px_end, px_pos, channels;
+	unsigned char *bytes;
+	const unsigned char *pixels;
+	qoi_rgba_t index[64];
+	qoi_rgba_t px, px_prev;
+
+	if (
+		data == NULL || out_len == NULL || desc == NULL ||
+		desc->width == 0 || desc->height == 0 ||
+		desc->channels < 3 || desc->channels > 4 ||
+		desc->colorspace > 1 ||
+		desc->height >= QOI_PIXELS_MAX / desc->width
+	) {
+		return NULL;
+	}
+
+	max_size =
+		desc->width * desc->height * (desc->channels + 1) +
+		QOI_HEADER_SIZE + sizeof(qoi_padding);
+
+	p = 0;
+	bytes = (unsigned char *) QOI_MALLOC(max_size);
+	if (!bytes) {
+		return NULL;
+	}
+
+	qoi_write_32(bytes, &p, QOI_MAGIC);
+	qoi_write_32(bytes, &p, desc->width);
+	qoi_write_32(bytes, &p, desc->height);
+	bytes[p++] = desc->channels;
+	bytes[p++] = desc->colorspace;
+
+
+	pixels = (const unsigned char *)data;
+
+	QOI_ZEROARR(index);
+
+	run = 0;
+	px_prev.rgba.r = 0;
+	px_prev.rgba.g = 0;
+	px_prev.rgba.b = 0;
+	px_prev.rgba.a = 255;
+	px = px_prev;
+
+	px_len = desc->width * desc->height * desc->channels;
+	px_end = px_len - desc->channels;
+	channels = desc->channels;
+
+	for (px_pos = 0; px_pos < px_len; px_pos += channels) {
+		if (channels == 4) {
+			px = *(qoi_rgba_t *)(pixels + px_pos);
+		}
+		else {
+			px.rgba.r = pixels[px_pos + 0];
+			px.rgba.g = pixels[px_pos + 1];
+			px.rgba.b = pixels[px_pos + 2];
+		}
+
+		if (px.v == px_prev.v) {
+			run++;
+			if (run == 62 || px_pos == px_end) {
+				bytes[p++] = QOI_OP_RUN | (run - 1);
+				run = 0;
+			}
+		}
+		else {
+			int index_pos;
+
+			if (run > 0) {
+				bytes[p++] = QOI_OP_RUN | (run - 1);
+				run = 0;
+			}
+
+			index_pos = QOI_COLOR_HASH(px) % 64;
+
+			if (index[index_pos].v == px.v) {
+				bytes[p++] = QOI_OP_INDEX | index_pos;
+			}
+			else {
+				index[index_pos] = px;
+
+				if (px.rgba.a == px_prev.rgba.a) {
+					signed char vr = px.rgba.r - px_prev.rgba.r;
+					signed char vg = px.rgba.g - px_prev.rgba.g;
+					signed char vb = px.rgba.b - px_prev.rgba.b;
+
+					signed char vg_r = vr - vg;
+					signed char vg_b = vb - vg;
+
+					if (
+						vr > -3 && vr < 2 &&
+						vg > -3 && vg < 2 &&
+						vb > -3 && vb < 2
+					) {
+						bytes[p++] = QOI_OP_DIFF | (vr + 2) << 4 | (vg + 2) << 2 | (vb + 2);
+					}
+					else if (
+						vg_r >  -9 && vg_r <  8 &&
+						vg   > -33 && vg   < 32 &&
+						vg_b >  -9 && vg_b <  8
+					) {
+						bytes[p++] = QOI_OP_LUMA     | (vg   + 32);
+						bytes[p++] = (vg_r + 8) << 4 | (vg_b +  8);
+					}
+					else {
+						bytes[p++] = QOI_OP_RGB;
+						bytes[p++] = px.rgba.r;
+						bytes[p++] = px.rgba.g;
+						bytes[p++] = px.rgba.b;
+					}
+				}
+				else {
+					bytes[p++] = QOI_OP_RGBA;
+					bytes[p++] = px.rgba.r;
+					bytes[p++] = px.rgba.g;
+					bytes[p++] = px.rgba.b;
+					bytes[p++] = px.rgba.a;
+				}
+			}
+		}
+		px_prev = px;
+	}
+
+	for (i = 0; i < (int)sizeof(qoi_padding); i++) {
+		bytes[p++] = qoi_padding[i];
+	}
+
+	*out_len = p;
+	return bytes;
+}
+
+void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels) {
+	const unsigned char *bytes;
+	unsigned int header_magic;
+	unsigned char *pixels;
+	qoi_rgba_t index[64];
+	qoi_rgba_t px;
+	int px_len, chunks_len, px_pos;
+	int p = 0, run = 0;
+
+	if (
+		data == NULL || desc == NULL ||
+		(channels != 0 && channels != 3 && channels != 4) ||
+		size < QOI_HEADER_SIZE + (int)sizeof(qoi_padding)
+	) {
+		return NULL;
+	}
+
+	bytes = (const unsigned char *)data;
+
+	header_magic = qoi_read_32(bytes, &p);
+	desc->width = qoi_read_32(bytes, &p);
+	desc->height = qoi_read_32(bytes, &p);
+	desc->channels = bytes[p++];
+	desc->colorspace = bytes[p++];
+
+	if (
+		desc->width == 0 || desc->height == 0 ||
+		desc->channels < 3 || desc->channels > 4 ||
+		desc->colorspace > 1 ||
+		header_magic != QOI_MAGIC ||
+		desc->height >= QOI_PIXELS_MAX / desc->width
+	) {
+		return NULL;
+	}
+
+	if (channels == 0) {
+		channels = desc->channels;
+	}
+
+	px_len = desc->width * desc->height * channels;
+	pixels = (unsigned char *) QOI_MALLOC(px_len);
+	if (!pixels) {
+		return NULL;
+	}
+
+	QOI_ZEROARR(index);
+	px.rgba.r = 0;
+	px.rgba.g = 0;
+	px.rgba.b = 0;
+	px.rgba.a = 255;
+
+	chunks_len = size - (int)sizeof(qoi_padding);
+	for (px_pos = 0; px_pos < px_len; px_pos += channels) {
+		if (run > 0) {
+			run--;
+		}
+		else if (p < chunks_len) {
+			int b1 = bytes[p++];
+
+			if (b1 == QOI_OP_RGB) {
+				px.rgba.r = bytes[p++];
+				px.rgba.g = bytes[p++];
+				px.rgba.b = bytes[p++];
+			}
+			else if (b1 == QOI_OP_RGBA) {
+				px.rgba.r = bytes[p++];
+				px.rgba.g = bytes[p++];
+				px.rgba.b = bytes[p++];
+				px.rgba.a = bytes[p++];
+			}
+			else if ((b1 & QOI_MASK_2) == QOI_OP_INDEX) {
+				px = index[b1];
+			}
+			else if ((b1 & QOI_MASK_2) == QOI_OP_DIFF) {
+				px.rgba.r += ((b1 >> 4) & 0x03) - 2;
+				px.rgba.g += ((b1 >> 2) & 0x03) - 2;
+				px.rgba.b += ( b1       & 0x03) - 2;
+			}
+			else if ((b1 & QOI_MASK_2) == QOI_OP_LUMA) {
+				int b2 = bytes[p++];
+				int vg = (b1 & 0x3f) - 32;
+				px.rgba.r += vg - 8 + ((b2 >> 4) & 0x0f);
+				px.rgba.g += vg;
+				px.rgba.b += vg - 8 +  (b2       & 0x0f);
+			}
+			else if ((b1 & QOI_MASK_2) == QOI_OP_RUN) {
+				run = (b1 & 0x3f);
+			}
+
+			index[QOI_COLOR_HASH(px) % 64] = px;
+		}
+
+		if (channels == 4) {
+			*(qoi_rgba_t*)(pixels + px_pos) = px;
+		}
+		else {
+			pixels[px_pos + 0] = px.rgba.r;
+			pixels[px_pos + 1] = px.rgba.g;
+			pixels[px_pos + 2] = px.rgba.b;
+		}
+	}
+
+	return pixels;
+}
+
+#ifndef QOI_NO_STDIO
+#include <stdio.h>
+
+int qoi_write(const char *filename, const void *data, const qoi_desc *desc) {
+	FILE *f = fopen(filename, "wb");
+	int size;
+	void *encoded;
+
+	if (!f) {
+		return 0;
+	}
+
+	encoded = qoi_encode(data, desc, &size);
+	if (!encoded) {
+		fclose(f);
+		return 0;
+	}
+
+	fwrite(encoded, 1, size, f);
+	fclose(f);
+
+	QOI_FREE(encoded);
+	return size;
+}
+
+void *qoi_read(const char *filename, qoi_desc *desc, int channels) {
+	FILE *f = fopen(filename, "rb");
+	int size, bytes_read;
+	void *pixels, *data;
+
+	if (!f) {
+		return NULL;
+	}
+
+	fseek(f, 0, SEEK_END);
+	size = ftell(f);
+	if (size <= 0) {
+		fclose(f);
+		return NULL;
+	}
+	fseek(f, 0, SEEK_SET);
+
+	data = QOI_MALLOC(size);
+	if (!data) {
+		fclose(f);
+		return NULL;
+	}
+
+	bytes_read = fread(data, 1, size, f);
+	fclose(f);
+
+	pixels = qoi_decode(data, bytes_read, desc, channels);
+	QOI_FREE(data);
+	return pixels;
+}
+
+#endif /* QOI_NO_STDIO */
+#endif /* QOI_IMPLEMENTATION */

qoi.mod/qoi/qoibench.c

@@ -0,0 +1,650 @@
+/*
+
+Simple benchmark suite for png, stbi and qoi
+
+Requires libpng, "stb_image.h" and "stb_image_write.h"
+Compile with: 
+	gcc qoibench.c -std=gnu99 -lpng -O3 -o qoibench 
+
+Dominic Szablewski - https://phoboslab.org
+
+
+-- LICENSE: The MIT License(MIT)
+
+Copyright(c) 2021 Dominic Szablewski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files(the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions :
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+*/
+
+#include <stdio.h>
+#include <dirent.h>
+#include <png.h>
+
+#define STB_IMAGE_IMPLEMENTATION
+#define STBI_ONLY_PNG
+#define STBI_NO_LINEAR
+#include "stb_image.h"
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+#define QOI_IMPLEMENTATION
+#include "qoi.h"
+
+
+
+
+// -----------------------------------------------------------------------------
+// Cross platform high resolution timer
+// From https://gist.github.com/ForeverZer0/0a4f80fc02b96e19380ebb7a3debbee5
+
+#include <stdint.h>
+#if defined(__linux)
+	#define HAVE_POSIX_TIMER
+	#include <time.h>
+	#ifdef CLOCK_MONOTONIC
+		#define CLOCKID CLOCK_MONOTONIC
+	#else
+		#define CLOCKID CLOCK_REALTIME
+	#endif
+#elif defined(__APPLE__)
+	#define HAVE_MACH_TIMER
+	#include <mach/mach_time.h>
+#elif defined(_WIN32)
+	#define WIN32_LEAN_AND_MEAN
+	#include <windows.h>
+#endif
+
+static uint64_t ns() {
+	static uint64_t is_init = 0;
+#if defined(__APPLE__)
+		static mach_timebase_info_data_t info;
+		if (0 == is_init) {
+			mach_timebase_info(&info);
+			is_init = 1;
+		}
+		uint64_t now;
+		now = mach_absolute_time();
+		now *= info.numer;
+		now /= info.denom;
+		return now;
+#elif defined(__linux)
+		static struct timespec linux_rate;
+		if (0 == is_init) {
+			clock_getres(CLOCKID, &linux_rate);
+			is_init = 1;
+		}
+		uint64_t now;
+		struct timespec spec;
+		clock_gettime(CLOCKID, &spec);
+		now = spec.tv_sec * 1.0e9 + spec.tv_nsec;
+		return now;
+#elif defined(_WIN32)
+		static LARGE_INTEGER win_frequency;
+		if (0 == is_init) {
+			QueryPerformanceFrequency(&win_frequency);
+			is_init = 1;
+		}
+		LARGE_INTEGER now;
+		QueryPerformanceCounter(&now);
+		return (uint64_t) ((1e9 * now.QuadPart)	/ win_frequency.QuadPart);
+#endif
+}
+
+#define STRINGIFY(x) #x
+#define TOSTRING(x) STRINGIFY(x)
+#define ERROR(...) printf("abort at line " TOSTRING(__LINE__) ": " __VA_ARGS__); printf("\n"); exit(1)
+
+
+// -----------------------------------------------------------------------------
+// libpng encode/decode wrappers
+// Seriously, who thought this was a good abstraction for an API to read/write
+// images?
+
+typedef struct {
+	int size;
+	int capacity;
+	unsigned char *data;
+} libpng_write_t;
+
+void libpng_encode_callback(png_structp png_ptr, png_bytep data, png_size_t length) {
+	libpng_write_t *write_data = (libpng_write_t*)png_get_io_ptr(png_ptr);
+	if (write_data->size + length >= write_data->capacity) {
+		ERROR("PNG write");
+	}
+	memcpy(write_data->data + write_data->size, data, length);
+	write_data->size += length;
+}
+
+void *libpng_encode(void *pixels, int w, int h, int channels, int *out_len) {
+	png_structp png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	if (!png) {
+		ERROR("png_create_write_struct");
+	}
+
+	png_infop info = png_create_info_struct(png);
+	if (!info) {
+		ERROR("png_create_info_struct");
+	}
+
+	if (setjmp(png_jmpbuf(png))) {
+		ERROR("png_jmpbuf");
+	}
+
+	// Output is 8bit depth, RGBA format.
+	png_set_IHDR(
+		png,
+		info,
+		w, h,
+		8,
+		channels == 3 ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGBA,
+		PNG_INTERLACE_NONE,
+		PNG_COMPRESSION_TYPE_DEFAULT,
+		PNG_FILTER_TYPE_DEFAULT
+	);
+
+	png_bytep row_pointers[h];
+	for(int y = 0; y < h; y++){
+		row_pointers[y] = ((unsigned char *)pixels + y * w * channels);
+	}
+
+	libpng_write_t write_data = {
+		.size = 0,
+		.capacity = w * h * channels,
+		.data = malloc(w * h * channels)
+	};
+
+	png_set_rows(png, info, row_pointers);
+	png_set_write_fn(png, &write_data, libpng_encode_callback, NULL);
+	png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);
+
+	png_destroy_write_struct(&png, &info);
+
+	*out_len = write_data.size;
+	return write_data.data;
+}
+
+
+typedef struct {
+	int pos;
+	int size;
+	unsigned char *data;
+} libpng_read_t;
+
+void png_decode_callback(png_structp png, png_bytep data, png_size_t length) {
+	libpng_read_t *read_data = (libpng_read_t*)png_get_io_ptr(png);
+	if (read_data->pos + length > read_data->size) {
+		ERROR("PNG read %d bytes at pos %d (size: %d)", length, read_data->pos, read_data->size);
+	}
+	memcpy(data, read_data->data + read_data->pos, length);
+	read_data->pos += length;
+}
+
+void png_warning_callback(png_structp png_ptr, png_const_charp warning_msg) {
+	// Ignore warnings about sRGB profiles and such.
+}
+
+void *libpng_decode(void *data, int size, int *out_w, int *out_h) {	
+	png_structp png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, png_warning_callback);
+	if (!png) {
+		ERROR("png_create_read_struct");
+	}
+
+	png_infop info = png_create_info_struct(png);
+	if (!info) {
+		ERROR("png_create_info_struct");
+	}
+
+	libpng_read_t read_data = {
+		.pos = 0,
+		.size = size,
+		.data = data
+	};
+	
+	png_set_read_fn(png, &read_data, png_decode_callback);
+	png_set_sig_bytes(png, 0);
+	png_read_info(png, info);
+	
+	png_uint_32 w, h;
+	int bitDepth, colorType, interlaceType;
+	png_get_IHDR(png, info, &w, &h, &bitDepth, &colorType, &interlaceType, NULL, NULL);
+	
+	// 16 bit -> 8 bit
+	png_set_strip_16(png);
+	
+	// 1, 2, 4 bit -> 8 bit
+	if (bitDepth < 8) {
+		png_set_packing(png);
+	}
+
+	if (colorType & PNG_COLOR_MASK_PALETTE) {
+		png_set_expand(png);
+	}
+	
+	if (!(colorType & PNG_COLOR_MASK_COLOR)) {
+		png_set_gray_to_rgb(png);
+	}
+
+	// set paletted or RGB images with transparency to full alpha so we get RGBA
+	if (png_get_valid(png, info, PNG_INFO_tRNS)) {
+		png_set_tRNS_to_alpha(png);
+	}
+	
+	// make sure every pixel has an alpha value
+	if (!(colorType & PNG_COLOR_MASK_ALPHA)) {
+		png_set_filler(png, 255, PNG_FILLER_AFTER);
+	}
+	
+	png_read_update_info(png, info);
+
+	unsigned char* out = malloc(w * h * 4);
+	*out_w = w;
+	*out_h = h;
+	
+	// png_uint_32 rowBytes = png_get_rowbytes(png, info);
+	png_bytep row_pointers[h];
+	for (png_uint_32 row = 0; row < h; row++ ) {
+		row_pointers[row] = (png_bytep)(out + (row * w * 4));
+	}
+	
+	png_read_image(png, row_pointers);
+	png_read_end(png, info);
+	png_destroy_read_struct( &png, &info, NULL);
+	
+	return out;
+}
+
+
+// -----------------------------------------------------------------------------
+// stb_image encode callback
+
+void stbi_write_callback(void *context, void *data, int size) {
+	int *encoded_size = (int *)context;
+	*encoded_size += size;
+	// In theory we'd need to do another malloc(), memcpy() and free() here to 
+	// be fair to the other decode functions...
+}
+
+
+// -----------------------------------------------------------------------------
+// function to load a whole file into memory
+
+void *fload(const char *path, int *out_size) {
+	FILE *fh = fopen(path, "rb");
+	if (!fh) {
+		ERROR("Can't open file");
+	}
+
+	fseek(fh, 0, SEEK_END);
+	int size = ftell(fh);
+	fseek(fh, 0, SEEK_SET);
+
+	void *buffer = malloc(size);
+	if (!buffer) {
+		ERROR("Malloc for %d bytes failed", size);
+	}
+
+	if (!fread(buffer, size, 1, fh)) {
+		ERROR("Can't read file %s", path);
+	}
+	fclose(fh);
+
+	*out_size = size;
+	return buffer;
+}
+
+
+// -----------------------------------------------------------------------------
+// benchmark runner
+
+
+int opt_runs = 1;
+int opt_nopng = 0;
+int opt_nowarmup = 0;
+int opt_noverify = 0;
+int opt_nodecode = 0;
+int opt_noencode = 0;
+int opt_norecurse = 0;
+int opt_onlytotals = 0;
+
+
+typedef struct {
+	uint64_t size;
+	uint64_t encode_time;
+	uint64_t decode_time;
+} benchmark_lib_result_t;
+
+typedef struct {
+	int count;
+	uint64_t raw_size;
+	uint64_t px;
+	int w;
+	int h;
+	benchmark_lib_result_t libpng;
+	benchmark_lib_result_t stbi;
+	benchmark_lib_result_t qoi;
+} benchmark_result_t;
+
+
+void benchmark_print_result(benchmark_result_t res) {
+	res.px /= res.count;
+	res.raw_size /= res.count;
+	res.libpng.encode_time /= res.count;
+	res.libpng.decode_time /= res.count;
+	res.libpng.size /= res.count;
+	res.stbi.encode_time /= res.count;
+	res.stbi.decode_time /= res.count;
+	res.stbi.size /= res.count;
+	res.qoi.encode_time /= res.count;
+	res.qoi.decode_time /= res.count;
+	res.qoi.size /= res.count;
+
+	double px = res.px;
+	printf("        decode ms   encode ms   decode mpps   encode mpps   size kb    rate\n");
+	if (!opt_nopng) {
+		printf(
+			"libpng:  %8.1f    %8.1f      %8.2f      %8.2f  %8d   %4.1f%%\n", 
+			(double)res.libpng.decode_time/1000000.0, 
+			(double)res.libpng.encode_time/1000000.0, 
+			(res.libpng.decode_time > 0 ? px / ((double)res.libpng.decode_time/1000.0) : 0),
+			(res.libpng.encode_time > 0 ? px / ((double)res.libpng.encode_time/1000.0) : 0),
+			res.libpng.size/1024,
+			((double)res.libpng.size/(double)res.raw_size) * 100.0
+		);
+		printf(
+			"stbi:    %8.1f    %8.1f      %8.2f      %8.2f  %8d   %4.1f%%\n", 
+			(double)res.stbi.decode_time/1000000.0,
+			(double)res.stbi.encode_time/1000000.0,
+			(res.stbi.decode_time > 0 ? px / ((double)res.stbi.decode_time/1000.0) : 0),
+			(res.stbi.encode_time > 0 ? px / ((double)res.stbi.encode_time/1000.0) : 0),
+			res.stbi.size/1024,
+			((double)res.stbi.size/(double)res.raw_size) * 100.0
+		);
+	}
+	printf(
+		"qoi:     %8.1f    %8.1f      %8.2f      %8.2f  %8d   %4.1f%%\n", 
+		(double)res.qoi.decode_time/1000000.0,
+		(double)res.qoi.encode_time/1000000.0,
+		(res.qoi.decode_time > 0 ? px / ((double)res.qoi.decode_time/1000.0) : 0),
+		(res.qoi.encode_time > 0 ? px / ((double)res.qoi.encode_time/1000.0) : 0),
+		res.qoi.size/1024,
+		((double)res.qoi.size/(double)res.raw_size) * 100.0
+	);
+	printf("\n");
+}
+
+// Run __VA_ARGS__ a number of times and measure the time taken. The first
+// run is ignored.
+#define BENCHMARK_FN(NOWARMUP, RUNS, AVG_TIME, ...) \
+	do { \
+		uint64_t time = 0; \
+		for (int i = NOWARMUP; i <= RUNS; i++) { \
+			uint64_t time_start = ns(); \
+			__VA_ARGS__ \
+			uint64_t time_end = ns(); \
+			if (i > 0) { \
+				time += time_end - time_start; \
+			} \
+		} \
+		AVG_TIME = time / RUNS; \
+	} while (0)
+
+
+benchmark_result_t benchmark_image(const char *path) {
+	int encoded_png_size;
+	int encoded_qoi_size;
+	int w;
+	int h;
+	int channels;
+
+	// Load the encoded PNG, encoded QOI and raw pixels into memory
+	if(!stbi_info(path, &w, &h, &channels)) {
+		ERROR("Error decoding header %s", path);
+	}
+
+	if (channels != 3) {
+		channels = 4;
+	}
+
+	void *pixels = (void *)stbi_load(path, &w, &h, NULL, channels);
+	void *encoded_png = fload(path, &encoded_png_size);
+	void *encoded_qoi = qoi_encode(pixels, &(qoi_desc){
+			.width = w,
+			.height = h, 
+			.channels = channels,
+			.colorspace = QOI_SRGB
+		}, &encoded_qoi_size);
+
+	if (!pixels || !encoded_qoi || !encoded_png) {
+		ERROR("Error decoding %s", path);
+	}
+
+	// Verify QOI Output
+
+	if (!opt_noverify) {
+		qoi_desc dc;
+		void *pixels_qoi = qoi_decode(encoded_qoi, encoded_qoi_size, &dc, channels);
+		if (memcmp(pixels, pixels_qoi, w * h * channels) != 0) {
+			ERROR("QOI roundtrip pixel mismatch for %s", path);
+		}
+		free(pixels_qoi);
+	}
+
+
+
+	benchmark_result_t res = {0};
+	res.count = 1;
+	res.raw_size = w * h * channels;
+	res.px = w * h;
+	res.w = w;
+	res.h = h;
+
+
+	// Decoding
+
+	if (!opt_nodecode) {
+		if (!opt_nopng) {
+			BENCHMARK_FN(opt_nowarmup, opt_runs, res.libpng.decode_time, {
+				int dec_w, dec_h;
+				void *dec_p = libpng_decode(encoded_png, encoded_png_size, &dec_w, &dec_h);
+				free(dec_p);
+			});
+
+			BENCHMARK_FN(opt_nowarmup, opt_runs, res.stbi.decode_time, {
+				int dec_w, dec_h, dec_channels;
+				void *dec_p = stbi_load_from_memory(encoded_png, encoded_png_size, &dec_w, &dec_h, &dec_channels, 4);
+				free(dec_p);
+			});
+		}
+
+		BENCHMARK_FN(opt_nowarmup, opt_runs, res.qoi.decode_time, {
+			qoi_desc desc;
+			void *dec_p = qoi_decode(encoded_qoi, encoded_qoi_size, &desc, 4);
+			free(dec_p);
+		});
+	}
+
+
+	// Encoding
+	if (!opt_noencode) {
+		if (!opt_nopng) {
+			BENCHMARK_FN(opt_nowarmup, opt_runs, res.libpng.encode_time, {
+				int enc_size;
+				void *enc_p = libpng_encode(pixels, w, h, channels, &enc_size);
+				res.libpng.size = enc_size;
+				free(enc_p);
+			});
+
+			BENCHMARK_FN(opt_nowarmup, opt_runs, res.stbi.encode_time, {
+				int enc_size = 0;
+				stbi_write_png_to_func(stbi_write_callback, &enc_size, w, h, channels, pixels, 0);
+				res.stbi.size = enc_size;
+			});
+		}
+
+		BENCHMARK_FN(opt_nowarmup, opt_runs, res.qoi.encode_time, {
+			int enc_size;
+			void *enc_p = qoi_encode(pixels, &(qoi_desc){
+				.width = w,
+				.height = h, 
+				.channels = channels,
+				.colorspace = QOI_SRGB
+			}, &enc_size);
+			res.qoi.size = enc_size;
+			free(enc_p);
+		});
+	}
+
+	free(pixels);
+	free(encoded_png);
+	free(encoded_qoi);
+
+	return res;
+}
+
+void benchmark_directory(const char *path, benchmark_result_t *grand_total) {
+	DIR *dir = opendir(path);
+	if (!dir) {
+		ERROR("Couldn't open directory %s", path);
+	}
+
+	struct dirent *file;
+
+	if (!opt_norecurse) {
+		for (int i = 0; (file = readdir(dir)) != NULL; i++) {
+			if (
+				file->d_type & DT_DIR &&
+				strcmp(file->d_name, ".") != 0 &&
+				strcmp(file->d_name, "..") != 0
+			) {
+				char subpath[1024];
+				snprintf(subpath, 1024, "%s/%s", path, file->d_name);
+				benchmark_directory(subpath, grand_total);
+			}
+		}
+		rewinddir(dir);
+	}
+
+	float total_percentage = 0;
+	int total_size = 0;
+
+	benchmark_result_t dir_total = {0};
+	
+	int has_shown_head = 0;
+	for (int i = 0; (file = readdir(dir)) != NULL; i++) {
+		if (strcmp(file->d_name + strlen(file->d_name) - 4, ".png") != 0) {
+			continue;
+		}
+
+		if (!has_shown_head) {
+			has_shown_head = 1;
+			printf("## Benchmarking %s/*.png -- %d runs\n\n", path, opt_runs);
+		}
+
+		char *file_path = malloc(strlen(file->d_name) + strlen(path)+8);
+		sprintf(file_path, "%s/%s", path, file->d_name);
+		
+		benchmark_result_t res = benchmark_image(file_path);
+
+		if (!opt_onlytotals) {
+			printf("## %s size: %dx%d\n", file_path, res.w, res.h);
+			benchmark_print_result(res);
+		}
+
+		free(file_path);
+		
+		dir_total.count++;
+		dir_total.raw_size += res.raw_size;
+		dir_total.px += res.px;
+		dir_total.libpng.encode_time += res.libpng.encode_time;
+		dir_total.libpng.decode_time += res.libpng.decode_time;
+		dir_total.libpng.size += res.libpng.size;
+		dir_total.stbi.encode_time += res.stbi.encode_time;
+		dir_total.stbi.decode_time += res.stbi.decode_time;
+		dir_total.stbi.size += res.stbi.size;
+		dir_total.qoi.encode_time += res.qoi.encode_time;
+		dir_total.qoi.decode_time += res.qoi.decode_time;
+		dir_total.qoi.size += res.qoi.size;
+
+		grand_total->count++;
+		grand_total->raw_size += res.raw_size;
+		grand_total->px += res.px;
+		grand_total->libpng.encode_time += res.libpng.encode_time;
+		grand_total->libpng.decode_time += res.libpng.decode_time;
+		grand_total->libpng.size += res.libpng.size;
+		grand_total->stbi.encode_time += res.stbi.encode_time;
+		grand_total->stbi.decode_time += res.stbi.decode_time;
+		grand_total->stbi.size += res.stbi.size;
+		grand_total->qoi.encode_time += res.qoi.encode_time;
+		grand_total->qoi.decode_time += res.qoi.decode_time;
+		grand_total->qoi.size += res.qoi.size;
+	}
+	closedir(dir);
+
+	if (dir_total.count > 0) {
+		printf("## Total for %s\n", path);
+		benchmark_print_result(dir_total);
+	}
+}
+
+int main(int argc, char **argv) {
+	if (argc < 3) {
+		printf("Usage: qoibench <iterations> <directory> [options]\n");
+		printf("Options:\n");
+		printf("    --nowarmup ... don't perform a warmup run\n");
+		printf("    --nopng ...... don't run png encode/decode\n");
+		printf("    --noverify ... don't verify qoi roundtrip\n");
+		printf("    --noencode ... don't run encoders\n");
+		printf("    --nodecode ... don't run decoders\n");
+		printf("    --norecurse .. don't descend into directories\n");
+		printf("    --onlytotals . don't print individual image results\n");
+		printf("Examples\n");
+		printf("    qoibench 10 images/textures/\n");
+		printf("    qoibench 1 images/textures/ --nopng --nowarmup\n");
+		exit(1);
+	}
+
+	for (int i = 3; i < argc; i++) {
+		if (strcmp(argv[i], "--nowarmup") == 0) { opt_nowarmup = 1; }
+		else if (strcmp(argv[i], "--nopng") == 0) { opt_nopng = 1; }
+		else if (strcmp(argv[i], "--noverify") == 0) { opt_noverify = 1; }
+		else if (strcmp(argv[i], "--noencode") == 0) { opt_noencode = 1; }
+		else if (strcmp(argv[i], "--nodecode") == 0) { opt_nodecode = 1; }
+		else if (strcmp(argv[i], "--norecurse") == 0) { opt_norecurse = 1; }
+		else if (strcmp(argv[i], "--onlytotals") == 0) { opt_onlytotals = 1; }
+		else { ERROR("Unknown option %s", argv[i]); }
+	}
+
+	opt_runs = atoi(argv[1]);
+	if (opt_runs <=0) {
+		ERROR("Invalid number of runs %d", opt_runs);
+	}
+
+	benchmark_result_t grand_total = {0};
+	benchmark_directory(argv[2], &grand_total);
+
+	if (grand_total.count > 0) {
+		printf("# Grand total for %s\n", argv[2]);
+		benchmark_print_result(grand_total);
+	}
+	else {
+		printf("No images found in %s\n", argv[2]);
+	}
+
+	return 0;
+}

qoi.mod/qoi/qoiconv.c

@@ -0,0 +1,106 @@
+/*
+
+Command line tool to convert between png <> qoi format
+
+Requires "stb_image.h" and "stb_image_write.h"
+Compile with: 
+	gcc qoiconv.c -std=c99 -O3 -o qoiconv
+
+Dominic Szablewski - https://phoboslab.org
+
+
+-- LICENSE: The MIT License(MIT)
+
+Copyright(c) 2021 Dominic Szablewski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files(the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions :
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+*/
+
+
+#define STB_IMAGE_IMPLEMENTATION
+#define STBI_ONLY_PNG
+#define STBI_NO_LINEAR
+#include "stb_image.h"
+
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+#include "stb_image_write.h"
+
+#define QOI_IMPLEMENTATION
+#include "qoi.h"
+
+
+#define STR_ENDS_WITH(S, E) (strcmp(S + strlen(S) - (sizeof(E)-1), E) == 0)
+
+int main(int argc, char **argv) {
+	if (argc < 3) {
+		puts("Usage: qoiconv <infile> <outfile>");
+		puts("Examples:");
+		puts("  qoiconv input.png output.qoi");
+		puts("  qoiconv input.qoi output.png");
+		exit(1);
+	}
+
+	void *pixels = NULL;
+	int w, h, channels;
+	if (STR_ENDS_WITH(argv[1], ".png")) {
+		if(!stbi_info(argv[1], &w, &h, &channels)) {
+			printf("Couldn't read header %s\n", argv[1]);
+			exit(1);
+		}
+
+		// Force all odd encodings to be RGBA
+		if(channels != 3) {
+			channels = 4;
+		}
+
+		pixels = (void *)stbi_load(argv[1], &w, &h, NULL, channels);
+	}
+	else if (STR_ENDS_WITH(argv[1], ".qoi")) {
+		qoi_desc desc;
+		pixels = qoi_read(argv[1], &desc, 0);
+		channels = desc.channels;
+		w = desc.width;
+		h = desc.height;
+	}
+
+	if (pixels == NULL) {
+		printf("Couldn't load/decode %s\n", argv[1]);
+		exit(1);
+	}
+
+	int encoded = 0;
+	if (STR_ENDS_WITH(argv[2], ".png")) {
+		encoded = stbi_write_png(argv[2], w, h, channels, pixels, 0);
+	}
+	else if (STR_ENDS_WITH(argv[2], ".qoi")) {
+		encoded = qoi_write(argv[2], pixels, &(qoi_desc){
+			.width = w,
+			.height = h, 
+			.channels = channels,
+			.colorspace = QOI_SRGB
+		});
+	}
+
+	if (!encoded) {
+		printf("Couldn't write/encode %s\n", argv[2]);
+		exit(1);
+	}
+
+	free(pixels);
+	return 0;
+}

qoi.mod/qoi/qoifuzz.c

@@ -0,0 +1,51 @@
+/*
+
+clang fuzzing harness for qoi_decode
+
+Compile and run with: 
+	clang -fsanitize=address,fuzzer -g -O0 qoifuzz.c && ./a.out
+
+Dominic Szablewski - https://phoboslab.org
+
+
+-- LICENSE: The MIT License(MIT)
+
+Copyright(c) 2021 Dominic Szablewski
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files(the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and / or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions :
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+*/
+
+
+#define QOI_IMPLEMENTATION
+#include "qoi.h"
+#include <stddef.h>
+#include <stdint.h>
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+	int w, h;
+	if (size < 4) {
+		return 0;
+	}
+
+	qoi_desc desc;
+	void* decoded = qoi_decode((void*)(data + 4), (int)(size - 4), &desc, *((int *)data));
+	if (decoded != NULL) {
+		free(decoded);
+	}
+	return 0;
+}