cute_aseprite.h

/*
	------------------------------------------------------------------------------
		Licensing information can be found at the end of the file.
	------------------------------------------------------------------------------

	cute_aseprite.h - v1.01

	To create implementation (the function definitions)
		#define CUTE_ASEPRITE_IMPLEMENTATION
	in *one* C/CPP file (translation unit) that includes this file


	SUMMARY

		cute_asesprite.h is a single-file header that implements some functions to
		parse .ase/.aseprite files. The entire file is parsed all at once and some
		structs are filled out then handed back to you.


	LIMITATIONS

		Only the "normal" blend mode for layers is supported. As a workaround try
		using the "merge down" function in Aseprite to create a normal layer.
		Supporting all blend modes would take too much code to be worth it.

		Does not support very old versions of Aseprite (with old palette chunks
		0x0004 or 0x0011). Also does not support deprecrated mask chunk.

		sRGB and ICC profiles are parsed but completely ignored when blending
		frames together. If you want these to be used when composing frames you
		have to do this yourself.


	SPECIAL THANKS

		Special thanks to Noel Berry for the blend code in his reference C++
		implementation (https://github.com/NoelFB/blah).

		Special thanks to Richard Mitton for the initial implementation of the
		zlib inflater.


	Revision history:
		1.00 (08/25/2020) initial release
		1.01 (08/31/2020) fixed memleaks, tag parsing bug (crash), blend bugs
*/

/*
	DOCUMENTATION

		Simply load an .ase or .aseprite file from disk or from memory like so.

			ase_t* ase = cute_aseprite_load_from_file("data/player.aseprite", NULL);


		Then access the fields directly, assuming you have your own `Animation` type.

			int w = ase->w;
			int h = ase->h;
			Animation anim = { 0 }; // Your custom animation data type.

			for (int i = 0; i < ase->frame_count; ++i) {
				ase_frame_t* frame = ase->frames + i;
				anim.add_frame(frame->duration, frame->pixels);
			}


		Then free it up when done.

			cute_aseprite_free(ase);


	DATA STRUCTURES

		Aseprite files have frames, layers, and cels. A single frame is one frame of an
		animation, formed by blending all the cels of an animation together. There is
		one cel per layer per frame. Each cel contains its own pixel data.

		The frame's pixels are automatically assumed to have been blended by the `normal`
		blend mode. A warning is emit if any other blend mode is encountered. Feel free
		to update the pixels of each frame with your own implementation of blending
		functions. The frame's pixels are merely provided like this for convenience.


	BUGS AND CRASHES

		This header is quite new and it takes time to test all the parse paths. Don't be
		shy about opening a GitHub issue if there's a crash! It's quite easy to update
		the parser as long as you upload your .ase file that shows the bug.

		https://github.com/RandyGaul/cute_headers/issues
*/

#ifndef CUTE_ASEPRITE_H
#define CUTE_ASEPRITE_H

typedef struct ase_t ase_t;

ase_t* cute_aseprite_load_from_file(const char* path, void* mem_ctx);
ase_t* cute_aseprite_load_from_memory(const void* memory, int size, void* mem_ctx);
void cute_aseprite_free(ase_t* aseprite);

#define CUTE_ASEPRITE_MAX_LAYERS (64)
#define CUTE_ASEPRITE_MAX_SLICES (128)
#define CUTE_ASEPRITE_MAX_PALETTE_ENTRIES (256)
#define CUTE_ASEPRITE_MAX_TAGS (256)

#include <stdint.h>

typedef struct ase_frame_t ase_frame_t;
typedef struct ase_layer_t ase_layer_t;
typedef struct ase_cel_t ase_cel_t;
typedef struct ase_tag_t ase_tag_t;
typedef struct ase_slice_t ase_slice_t;
typedef struct ase_palette_entry_t ase_palette_entry_t;
typedef struct ase_palette_t ase_palette_t;
typedef struct ase_udata_t ase_udata_t;
typedef struct ase_cel_extra_chunk_t ase_cel_extra_chunk_t;
typedef struct ase_color_profile_t ase_color_profile_t;
typedef struct ase_fixed_t ase_fixed_t;
typedef struct ase_cel_extra_chunk_t ase_cel_extra_chunk_t;

struct ase_color_t
{
	uint8_t r, g, b, a;
};

struct ase_fixed_t
{
	uint16_t a;
	uint16_t b;
};

struct ase_udata_t
{
	int has_color;
	ase_color_t color;
	int has_text;
	const char* text;
};

typedef enum ase_layer_flags_t
{
	ASE_LAYER_FLAGS_VISIBLE            = 0x01,
	ASE_LAYER_FLAGS_EDITABLE           = 0x02,
	ASE_LAYER_FLAGS_LOCK_MOVEMENT      = 0x04,
	ASE_LAYER_FLAGS_BACKGROUND         = 0x08,
	ASE_LAYER_FLAGS_PREFER_LINKED_CELS = 0x10,
	ASE_LAYER_FLAGS_COLLAPSED          = 0x20,
	ASE_LAYER_FLAGS_REFERENCE          = 0x40,
} ase_layer_flags_t;

typedef enum ase_layer_type_t
{
	ASE_LAYER_TYPE_NORMAL,
	ASE_LAYER_TYPE_GROUP,
} ase_layer_type_t;

struct ase_layer_t
{
	ase_layer_flags_t flags;
	ase_layer_type_t type;
	const char* name;
	int child_level;
	float opacity;
	ase_udata_t udata;
};

struct ase_cel_extra_chunk_t
{
	int precise_bounds_are_set;
	ase_fixed_t precise_x;
	ase_fixed_t precise_y;
	ase_fixed_t w, h;
};

struct ase_cel_t
{
	ase_layer_t* layer;
	void* pixels;
	int w, h;
	int x, y;
	float opacity;
	int is_linked;
	uint16_t linked_frame_index;
	int has_extra;
	ase_cel_extra_chunk_t extra;
	ase_udata_t udata;
};

struct ase_frame_t
{
	ase_t* ase;
	int duration_milliseconds;
	ase_color_t* pixels;
	int cel_count;
	ase_cel_t cels[CUTE_ASEPRITE_MAX_LAYERS];
};

typedef enum ase_animation_direction_t
{
	ASE_ANIMATION_DIRECTION_FORWARDS,
	ASE_ANIMATION_DIRECTION_BACKWORDS,
	ASE_ANIMATION_DIRECTION_PINGPONG,
} ase_animation_direction_t;

struct ase_tag_t
{
	int from_frame;
	int to_frame;
	ase_animation_direction_t loop_animation_direction;
	uint8_t r, g, b;
	const char* name;
};

struct ase_slice_t
{
	const char* name;
	int frame_number;
	int origin_x;
	int origin_y;
	int w, h;

	int has_center_as_9_slice;
	int center_x;
	int center_y;
	int center_w;
	int center_h;

	int has_pivot;
	int pivot_x;
	int pivot_y;

	ase_udata_t udata;
};

struct ase_palette_entry_t
{
	ase_color_t color;
	const char* color_name;
};

struct ase_palette_t
{
	int entry_count;
	ase_palette_entry_t entries[CUTE_ASEPRITE_MAX_PALETTE_ENTRIES];
};

typedef enum ase_color_profile_type_t
{
	ASE_COLOR_PROFILE_TYPE_NONE,
	ASE_COLOR_PROFILE_TYPE_SRGB,
	ASE_COLOR_PROFILE_TYPE_EMBEDDED_ICC,
} ase_color_profile_type_t;

struct ase_color_profile_t
{
	ase_color_profile_type_t type;
	int use_fixed_gamma;
	ase_fixed_t gamma;
	uint32_t icc_profile_data_length;
	void* icc_profile_data;
};

typedef enum ase_mode_t
{
	ASE_MODE_RGBA,
	ASE_MODE_GRAYSCALE,
	ASE_MODE_INDEXED
} ase_mode_t;

struct ase_t
{
	ase_mode_t mode;
	int w, h;
	int transparent_palette_entry_index;
	int number_of_colors;
	int pixel_w;
	int pixel_h;
	int grid_x;
	int grid_y;
	int grid_w;
	int grid_h;
	int has_color_profile;
	ase_color_profile_t color_profile;
	ase_palette_t palette;

	int layer_count;
	ase_layer_t layers[CUTE_ASEPRITE_MAX_LAYERS];

	int frame_count;
	ase_frame_t* frames;

	int tag_count;
	ase_tag_t tags[CUTE_ASEPRITE_MAX_TAGS];

	int slice_count;
	ase_slice_t slices[CUTE_ASEPRITE_MAX_SLICES];

	void* mem_ctx;
};

#endif // CUTE_ASEPRITE_H

#ifdef CUTE_ASEPRITE_IMPLEMENTATION
#ifndef CUTE_ASEPRITE_IMPLEMENTATION_ONCE
#define CUTE_ASEPRITE_IMPLEMENTATION_ONCE

#ifndef _CRT_SECURE_NO_WARNINGS
	#define _CRT_SECURE_NO_WARNINGS
#endif

#ifndef _CRT_NONSTDC_NO_DEPRECATE
	#define _CRT_NONSTDC_NO_DEPRECATE
#endif

#if !defined(CUTE_ASEPRITE_ALLOC)
	#include <stdlib.h>
	#define CUTE_ASEPRITE_ALLOC(size, ctx) malloc(size)
	#define CUTE_ASEPRITE_FREE(mem, ctx) free(mem)
#endif

#if !defined(CUTE_ASEPRITE_UNUSED)
	#if defined(_MSC_VER)
		#define CUTE_ASEPRITE_UNUSED(x) (void)x
	#else
		#define CUTE_ASEPRITE_UNUSED(x) (void)(sizeof(x))
	#endif
#endif

#if !defined(CUTE_ASEPRITE_MEMCPY)
	#include <string.h> // memcpy
	#define CUTE_ASEPRITE_MEMCPY memcpy
#endif

#if !defined(CUTE_ASEPRITE_MEMSET)
	#include <string.h> // memset
	#define CUTE_ASEPRITE_MEMSET memset
#endif

#if !defined(CUTE_ASEPRITE_ASSERT)
	#include <assert.h>
	#define CUTE_ASEPRITE_ASSERT assert
#endif

static int s_error_cline;               // The line in cute_aseprite.h where the error was triggered.
static const char* s_error_file = NULL; // The filepath of the file being parsed. NULL if from memory.
static const char* s_error_reason;      // Used to capture errors during DEFLATE parsing.

#if !defined(CUTE_ASEPRITE_WARNING)
	#define CUTE_ASEPRITE_WARNING(msg) cute_aseprite_warning(msg, __LINE__)

	void cute_aseprite_warning(const char* warning, int line)
	{
		s_error_cline = line;
		const char *error_file = s_error_file ? s_error_file : "MEMORY";
		printf("WARNING (cute_aseprite.h:%i): %s (%s)\n", s_error_cline, warning, error_file);
	}
#endif

#define CUTE_ASEPRITE_FAIL() do { goto ase_err; } while (0)
#define CUTE_ASEPRITE_CHECK(X, Y) do { if (!(X)) { s_error_reason = Y; CUTE_ASEPRITE_FAIL(); } } while (0)
#define CUTE_ASEPRITE_CALL(X) do { if (!(X)) goto ase_err; } while (0)
#define CUTE_ASEPRITE_DEFLATE_MAX_BITLEN 15

// DEFLATE tables from RFC 1951
static uint8_t s_fixed_table[288 + 32] = {
	8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
	8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
	8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
	9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,
	7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
}; // 3.2.6
static uint8_t s_permutation_order[19] = { 16,17,18,0,8,7,9,6,10,5,11,4,12,3,13,2,14,1,15 }; // 3.2.7
static uint8_t s_len_extra_bits[29 + 2] = { 0,0,0,0,0,0,0,0,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5,0,  0,0 }; // 3.2.5
static uint32_t s_len_base[29 + 2] = { 3,4,5,6,7,8,9,10,11,13,15,17,19,23,27,31,35,43,51,59,67,83,99,115,131,163,195,227,258,  0,0 }; // 3.2.5
static uint8_t s_dist_extra_bits[30 + 2] = { 0,0,0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,13,13,  0,0 }; // 3.2.5
static uint32_t s_dist_base[30 + 2] = { 1,2,3,4,5,7,9,13,17,25,33,49,65,97,129,193,257,385,513,769,1025,1537,2049,3073,4097,6145,8193,12289,16385,24577, 0,0 }; // 3.2.5

typedef struct deflate_t
{
	uint64_t bits;
	int count;
	uint32_t* words;
	int word_count;
	int word_index;
	int bits_left;

	int final_word_available;
	uint32_t final_word;

	char* out;
	char* out_end;
	char* begin;

	uint32_t lit[288];
	uint32_t dst[32];
	uint32_t len[19];
	uint32_t nlit;
	uint32_t ndst;
	uint32_t nlen;
} deflate_t;

static int s_would_overflow(deflate_t* s, int num_bits)
{
	return (s->bits_left + s->count) - num_bits < 0;
}

static char* s_ptr(deflate_t* s)
{
	CUTE_ASEPRITE_ASSERT(!(s->bits_left & 7));
	return (char*)(s->words + s->word_index) - (s->count / 8);
}

static uint64_t s_peak_bits(deflate_t* s, int num_bits_to_read)
{
	if (s->count < num_bits_to_read)
	{
		if (s->word_index < s->word_count)
		{
			uint32_t word = s->words[s->word_index++];
			s->bits |= (uint64_t)word << s->count;
			s->count += 32;
			CUTE_ASEPRITE_ASSERT(s->word_index <= s->word_count);
		}

		else if (s->final_word_available)
		{
			uint32_t word = s->final_word;
			s->bits |= (uint64_t)word << s->count;
			s->count += s->bits_left;
			s->final_word_available = 0;
		}
	}

	return s->bits;
}

static uint32_t s_consume_bits(deflate_t* s, int num_bits_to_read)
{
	CUTE_ASEPRITE_ASSERT(s->count >= num_bits_to_read);
	uint32_t bits = s->bits & (((uint64_t)1 << num_bits_to_read) - 1);
	s->bits >>= num_bits_to_read;
	s->count -= num_bits_to_read;
	s->bits_left -= num_bits_to_read;
	return bits;
}

static uint32_t s_read_bits(deflate_t* s, int num_bits_to_read)
{
	CUTE_ASEPRITE_ASSERT(num_bits_to_read <= 32);
	CUTE_ASEPRITE_ASSERT(num_bits_to_read >= 0);
	CUTE_ASEPRITE_ASSERT(s->bits_left > 0);
	CUTE_ASEPRITE_ASSERT(s->count <= 64);
	CUTE_ASEPRITE_ASSERT(!s_would_overflow(s, num_bits_to_read));
	s_peak_bits(s, num_bits_to_read);
	uint32_t bits = s_consume_bits(s, num_bits_to_read);
	return bits;
}

static uint32_t s_rev16(uint32_t a)
{
	a = ((a & 0xAAAA) >>  1) | ((a & 0x5555) << 1);
	a = ((a & 0xCCCC) >>  2) | ((a & 0x3333) << 2);
	a = ((a & 0xF0F0) >>  4) | ((a & 0x0F0F) << 4);
	a = ((a & 0xFF00) >>  8) | ((a & 0x00FF) << 8);
	return a;
}

// RFC 1951 section 3.2.2
static int s_build(deflate_t* s, uint32_t* tree, uint8_t* lens, int sym_count)
{
	int n, codes[16], first[16], counts[16] = { 0 };

	// Frequency count
	for (n = 0; n < sym_count; n++) counts[lens[n]]++;

	// Distribute codes
	counts[0] = codes[0] = first[0] = 0;
	for (n = 1; n <= 15; ++n)
	{
		codes[n] = (codes[n - 1] + counts[n - 1]) << 1;
		first[n] = first[n - 1] + counts[n - 1];
	}

	for (int i = 0; i < sym_count; ++i)
	{
		int len = lens[i];

		if (len != 0)
		{
			CUTE_ASEPRITE_ASSERT(len < 16);
			uint32_t code = codes[len]++;
			uint32_t slot = first[len]++;
			tree[slot] = (code << (32 - len)) | (i << 4) | len;
		}
	}

	int max_index = first[15];
	return max_index;
}

static int s_stored(deflate_t* s)
{
	char* p;

	// 3.2.3
	// skip any remaining bits in current partially processed byte
	s_read_bits(s, s->count & 7);

	// 3.2.4
	// read LEN and NLEN, should complement each other
	uint16_t LEN = (uint16_t)s_read_bits(s, 16);
	uint16_t NLEN = (uint16_t)s_read_bits(s, 16);
	CUTE_ASEPRITE_CHECK(LEN == (uint16_t)(~NLEN), "Failed to find LEN and NLEN as complements within stored (uncompressed) stream.");
	CUTE_ASEPRITE_CHECK(s->bits_left / 8 <= (int)LEN, "Stored block extends beyond end of input stream.");
	p = s_ptr(s);
	CUTE_ASEPRITE_MEMCPY(s->out, p, LEN);
	s->out += LEN;
	return 1;

ase_err:
	return 0;
}

// 3.2.6
static int s_fixed(deflate_t* s)
{
	s->nlit = s_build(s, s->lit, s_fixed_table, 288);
	s->ndst = s_build(0, s->dst, s_fixed_table + 288, 32);
	return 1;
}

static int s_decode(deflate_t* s, uint32_t* tree, int hi)
{
	uint64_t bits = s_peak_bits(s, 16);
	uint32_t search = (s_rev16((uint32_t)bits) << 16) | 0xFFFF;
	int lo = 0;
	while (lo < hi)
	{
		int guess = (lo + hi) >> 1;
		if (search < tree[guess]) hi = guess;
		else lo = guess + 1;
	}

	uint32_t key = tree[lo - 1];
	uint32_t len = (32 - (key & 0xF));
	CUTE_ASEPRITE_ASSERT((search >> len) == (key >> len));

	int code = s_consume_bits(s, key & 0xF);
	(void)code;
	return (key >> 4) & 0xFFF;
}

// 3.2.7
static int s_dynamic(deflate_t* s)
{
	uint8_t lenlens[19] = { 0 };

	int nlit = 257 + s_read_bits(s, 5);
	int ndst = 1 + s_read_bits(s, 5);
	int nlen = 4 + s_read_bits(s, 4);

	for (int i = 0 ; i < nlen; ++i)
		lenlens[s_permutation_order[i]] = (uint8_t)s_read_bits(s, 3);

	// Build the tree for decoding code lengths
	s->nlen = s_build(0, s->len, lenlens, 19);
	uint8_t lens[288 + 32];

	for (int n = 0; n < nlit + ndst;)
	{
		int sym = s_decode(s, s->len, s->nlen);
		switch (sym)
		{
		case 16: for (int i =  3 + s_read_bits(s, 2); i; --i, ++n) lens[n] = lens[n - 1]; break;
		case 17: for (int i =  3 + s_read_bits(s, 3); i; --i, ++n) lens[n] = 0; break;
		case 18: for (int i = 11 + s_read_bits(s, 7); i; --i, ++n) lens[n] = 0; break;
		default: lens[n++] = (uint8_t)sym; break;
		}
	}

	s->nlit = s_build(s, s->lit, lens, nlit);
	s->ndst = s_build(0, s->dst, lens + nlit, ndst);
	return 1;
}

// 3.2.3
static int s_block(deflate_t* s)
{
	while (1)
	{
		int symbol = s_decode(s, s->lit, s->nlit);

		if (symbol < 256)
		{
			CUTE_ASEPRITE_CHECK(s->out + 1 <= s->out_end, "Attempted to overwrite out buffer while outputting a symbol.");
			*s->out = (char)symbol;
			s->out += 1;
		}

		else if (symbol > 256)
		{
			symbol -= 257;
			int length = s_read_bits(s, s_len_extra_bits[symbol]) + s_len_base[symbol];
			int distance_symbol = s_decode(s, s->dst, s->ndst);
			int backwards_distance = s_read_bits(s, s_dist_extra_bits[distance_symbol]) + s_dist_base[distance_symbol];
			CUTE_ASEPRITE_CHECK(s->out - backwards_distance >= s->begin, "Attempted to write before out buffer (invalid backwards distance).");
			CUTE_ASEPRITE_CHECK(s->out + length <= s->out_end, "Attempted to overwrite out buffer while outputting a string.");
			char* src = s->out - backwards_distance;
			char* dst = s->out;
			s->out += length;

			switch (backwards_distance)
			{
			case 1: // very common in images
				CUTE_ASEPRITE_MEMSET(dst, *src, length);
				break;
			default: while (length--) *dst++ = *src++;
			}
		}

		else break;
	}

	return 1;

ase_err:
	return 0;
}

// 3.2.3
static int s_inflate(const void* in, int in_bytes, void* out, int out_bytes, void* mem_ctx)
{
	deflate_t* s = (deflate_t*)CUTE_ASEPRITE_ALLOC(sizeof(deflate_t), mem_ctx);
	s->bits = 0;
	s->count = 0;
	s->word_index = 0;
	s->bits_left = in_bytes * 8;

	// s->words is the in-pointer rounded up to a multiple of 4
	int first_bytes = (int)((((size_t)in + 3) & ~3) - (size_t)in);
	s->words = (uint32_t*)((char*)in + first_bytes);
	s->word_count = (in_bytes - first_bytes) / 4;
	int last_bytes = ((in_bytes - first_bytes) & 3);

	for (int i = 0; i < first_bytes; ++i)
		s->bits |= (uint64_t)(((uint8_t*)in)[i]) << (i * 8);

	s->final_word_available = last_bytes ? 1 : 0;
	s->final_word = 0;
	for(int i = 0; i < last_bytes; i++)
		s->final_word |= ((uint8_t*)in)[in_bytes - last_bytes+i] << (i * 8);

	s->count = first_bytes * 8;

	s->out = (char*)out;
	s->out_end = s->out + out_bytes;
	s->begin = (char*)out;

	int count = 0;
	int bfinal;
	do
	{
		bfinal = s_read_bits(s, 1);
		int btype = s_read_bits(s, 2);

		switch (btype)
		{
		case 0: CUTE_ASEPRITE_CALL(s_stored(s)); break;
		case 1: s_fixed(s); CUTE_ASEPRITE_CALL(s_block(s)); break;
		case 2: s_dynamic(s); CUTE_ASEPRITE_CALL(s_block(s)); break;
		case 3: CUTE_ASEPRITE_CHECK(0, "Detected unknown block type within input stream.");
		}

		++count;
	}
	while (!bfinal);

	CUTE_ASEPRITE_FREE(s, mem_ctx);
	return 1;

ase_err:
	CUTE_ASEPRITE_FREE(s, mem_ctx);
	return 0;
}

typedef struct ase_state_t
{
	uint8_t* in;
	uint8_t* end;
	void* mem_ctx;
} ase_state_t;

static uint8_t s_read_uint8(ase_state_t* s)
{
	CUTE_ASEPRITE_ASSERT(s->in <= s->end + sizeof(uint8_t));
	uint8_t** p = &s->in;
	uint8_t value = **p;
	++(*p);
	return value;
}

static uint16_t s_read_uint16(ase_state_t* s)
{
	CUTE_ASEPRITE_ASSERT(s->in <= s->end + sizeof(uint16_t));
	uint8_t** p = &s->in;
	uint16_t value;
	value = (*p)[0];
	value |= (((uint16_t)((*p)[1])) << 8);
	*p += 2;
	return value;
}

static ase_fixed_t s_read_fixed(ase_state_t* s)
{
	ase_fixed_t value;
	value.a = s_read_uint16(s);
	value.b = s_read_uint16(s);
	return value;
}

static uint32_t s_read_uint32(ase_state_t* s)
{
	CUTE_ASEPRITE_ASSERT(s->in <= s->end + sizeof(uint32_t));
	uint8_t** p = &s->in;
	uint32_t value;
	value  = (*p)[0];
	value |= (((uint32_t)((*p)[1])) << 8);
	value |= (((uint32_t)((*p)[2])) << 16);
	value |= (((uint32_t)((*p)[3])) << 24);
	*p += 4;
	return value;
}

static uint64_t s_read_uint64(ase_state_t* s)
{
	CUTE_ASEPRITE_ASSERT(s->in <= s->end + sizeof(uint64_t));
	uint8_t** p = &s->in;
	uint64_t value;
	value  = (*p)[0];
	value |= (((uint64_t)((*p)[1])) << 8 );
	value |= (((uint64_t)((*p)[2])) << 16);
	value |= (((uint64_t)((*p)[3])) << 24);
	value |= (((uint64_t)((*p)[4])) << 32);
	value |= (((uint64_t)((*p)[5])) << 40);
	value |= (((uint64_t)((*p)[6])) << 48);
	value |= (((uint64_t)((*p)[7])) << 56);
	*p += 8;
	return value;
}

static int16_t s_read_int16(ase_state_t* s) { return (int16_t)s_read_uint16(s); }
static int16_t s_read_int32(ase_state_t* s) { return (int32_t)s_read_uint32(s); }

static void s_read_bytes(ase_state_t* s, uint8_t* bytes, int num_bytes)
{
	for (int i = 0; i < num_bytes; ++i) {
		bytes[i] = s_read_uint8(s);
	}
}

static const char* s_read_string(ase_state_t* s)
{
	int len = (int)s_read_uint16(s);
	char* bytes = (char*)CUTE_ASEPRITE_ALLOC(len + 1, s->mem_ctx);
	for (int i = 0; i < len; ++i) {
		bytes[i] = s_read_uint8(s);
	}
	bytes[len] = 0;
	return bytes;
}

static void s_skip(ase_state_t* ase, int num_bytes)
{
	CUTE_ASEPRITE_ASSERT(ase->in <= ase->end + num_bytes);
	ase->in += num_bytes;
}

static char* s_fopen(const char* path, int* size, void* mem_ctx)
{
	CUTE_ASEPRITE_UNUSED(mem_ctx);
	char* data = 0;
	FILE* fp = fopen(path, "rb");
	int sz = 0;

	if (fp)
	{
		fseek(fp, 0, SEEK_END);
		sz = ftell(fp);
		fseek(fp, 0, SEEK_SET);
		data = (char*)CUTE_ASEPRITE_ALLOC(sz + 1, mem_ctx);
		fread(data, sz, 1, fp);
		data[sz] = 0;
		fclose(fp);
	}

	if (size) *size = sz;
	return data;
}

ase_t* cute_aseprite_load_from_file(const char* path, void* mem_ctx)
{
	s_error_file = path;
	int sz;
	void* file = s_fopen(path, &sz, mem_ctx);
	if (!file) {
		CUTE_ASEPRITE_WARNING("Unable to find map file.");
		return NULL;
	}
	ase_t* aseprite = cute_aseprite_load_from_memory(file, sz, mem_ctx);
	CUTE_ASEPRITE_FREE(file, mem_ctx);
	s_error_file = NULL;
	return aseprite;
}

static int s_mul_un8(int a, int b)
{
	int t = (a * b) + 0x80;
	return (((t >> 8) + t) >> 8);
}

static ase_color_t s_blend(ase_color_t src, ase_color_t dst, uint8_t opacity)
{
	src.a = s_mul_un8(src.a, opacity);
	int a = src.a + dst.a - s_mul_un8(src.a, dst.a);
	int r, g, b;
	if (a == 0) {
		r = g = b = 0;
	} else {
		r = dst.r + (src.r - dst.r) * src.a / a;
		g = dst.g + (src.g - dst.g) * src.a / a;
		b = dst.b + (src.b - dst.b) * src.a / a;
	}
	return { (uint8_t)r, (uint8_t)g, (uint8_t)b, (uint8_t)a };
}

static int s_min(int a, int b)
{
	return a < b ? a : b;
}

static int s_max(int a, int b)
{
	return a < b ? b : a;
}

static ase_color_t s_color(ase_t* ase, void* src, int index)
{
	ase_color_t result;
	if (ase->mode == ASE_MODE_RGBA) {
		result = ((ase_color_t*)src)[index];
	} else if (ase->mode == ASE_MODE_GRAYSCALE) {
		uint8_t saturation = ((uint8_t*)src)[index * 2];
		uint8_t a = ((uint8_t*)src)[index * 2 + 1];
		result.r = result.g = result.b = saturation;
		result.a = a;
	} else {
		CUTE_ASEPRITE_ASSERT(ase->mode == ASE_MODE_INDEXED);
		uint8_t palette_index = ((uint8_t*)src)[index];
		result = ase->palette.entries[palette_index].color;
	}
	return result;
}

ase_t* cute_aseprite_load_from_memory(const void* memory, int size, void* mem_ctx)
{
	ase_t* ase = (ase_t*)CUTE_ASEPRITE_ALLOC(sizeof(ase_t), mem_ctx);
	CUTE_ASEPRITE_MEMSET(ase, 0, sizeof(*ase));

	ase_state_t state = { 0 };
	ase_state_t* s = &state;
	s->in = (uint8_t*)memory;
	s->end = s->in + size;
	s->mem_ctx = mem_ctx;

	s_skip(s, sizeof(uint32_t)); // File size.
	int magic = (int)s_read_uint16(s);
	CUTE_ASEPRITE_ASSERT(magic == 0xA5E0);

	ase->frame_count = (int)s_read_uint16(s);
	ase->w = s_read_uint16(s);
	ase->h = s_read_uint16(s);
	uint16_t bpp = s_read_uint16(s) / 8;
	if (bpp == 4) ase->mode = ASE_MODE_RGBA;
	else if (bpp == 2) ase->mode = ASE_MODE_GRAYSCALE;
	else {
		CUTE_ASEPRITE_ASSERT(bpp == 1);
		ase->mode = ASE_MODE_INDEXED;
	}
	if (s_read_uint32(s) & 1) {
		// Layer opacity has valid value.
		// Ok... So?
	}
	int speed = s_read_uint16(s);
	s_skip(s, sizeof(uint32_t) * 2); // Spec says skip these bytes, as they're zero'd.
	ase->transparent_palette_entry_index = s_read_uint8(s);
	s_skip(s, 3); // Spec says skip these bytes.
	ase->number_of_colors = (int)s_read_uint16(s);
	ase->pixel_w = (int)s_read_uint8(s);
	ase->pixel_h = (int)s_read_uint8(s);
	ase->grid_x = (int)s_read_int16(s);
	ase->grid_y = (int)s_read_int16(s);
	ase->grid_w = (int)s_read_uint16(s);
	ase->grid_h = (int)s_read_uint16(s);
	s_skip(s, 84); // For future use (set to zero).

	ase->frames = (ase_frame_t*)CUTE_ASEPRITE_ALLOC(sizeof(ase_frame_t) * ase->frame_count, mem_ctx);
	CUTE_ASEPRITE_MEMSET(ase->frames, 0, sizeof(ase_frame_t) * ase->frame_count);

	ase_udata_t* last_udata = NULL;

	// Parse all chunks in the .aseprite file.
	for (int i = 0; i < ase->frame_count; ++i) {
		ase_frame_t* frame = ase->frames + i;
		frame->ase = ase;
		s_skip(s, sizeof(uint32_t)); // Frame size.
		magic = (int)s_read_uint16(s);
		CUTE_ASEPRITE_ASSERT(magic == 0xF1FA);
		int chunk_count = (int)s_read_uint16(s);
		frame->duration_milliseconds = s_read_uint16(s);
		if (frame->duration_milliseconds == 0) frame->duration_milliseconds = speed;
		s_skip(s, 2); // For future use (set to zero).
		int new_chunk_count = s_read_uint32(s);
		if (new_chunk_count) chunk_count = new_chunk_count;

		for (int j = 0; j < chunk_count; ++j) {
			uint32_t chunk_size = s_read_uint32(s);
			uint16_t chunk_type = s_read_uint16(s);
			chunk_size -= sizeof(uint32_t) + sizeof(uint16_t);
			uint8_t* chunk_start = s->in;

			switch (chunk_type) {
			case 0x2004: // Layer chunk.
			{
				CUTE_ASEPRITE_ASSERT(ase->layer_count < CUTE_ASEPRITE_MAX_LAYERS);
				ase_layer_t* layer = ase->layers + ase->layer_count++;
				layer->flags = (ase_layer_flags_t)s_read_uint16(s);
				layer->type = (ase_layer_type_t)s_read_uint16(s);
				layer->child_level = (int)s_read_uint16(s);
				s_skip(s, sizeof(uint16_t)); // Default layer width in pixels (ignored).
				s_skip(s, sizeof(uint16_t)); // Default layer height in pixels (ignored).
				int blend_mode = (int)s_read_uint16(s);
				if (blend_mode) CUTE_ASEPRITE_WARNING("Unknown blend mode encountered.");
				layer->opacity = s_read_uint8(s) / 255.0f;
				s_skip(s, 3); // For future use (set to zero).
				layer->name = s_read_string(s);
				last_udata = &layer->udata;
			}	break;

			case 0x2005: // Cel chunk.
			{
				CUTE_ASEPRITE_ASSERT(frame->cel_count < CUTE_ASEPRITE_MAX_LAYERS);
				ase_cel_t* cel = frame->cels + frame->cel_count++;
				int layer_index = (int)s_read_uint16(s);
				cel->layer = ase->layers + layer_index;
				cel->x = s_read_int16(s);
				cel->y = s_read_int16(s);
				cel->opacity = s_read_uint8(s) / 255.0f;
				int cel_type = (int)s_read_uint16(s);
				s_skip(s, 7); // For future (set to zero).
				switch (cel_type) {
				case 0: // Raw cel.
					cel->w = s_read_uint16(s);
					cel->h = s_read_uint16(s);
					cel->pixels = CUTE_ASEPRITE_ALLOC(cel->w * cel->h * bpp, mem_ctx);
					CUTE_ASEPRITE_MEMCPY(cel->pixels, s->in, cel->w * cel->h * bpp);
					s_skip(s, cel->w * cel->h * bpp);
					break;

				case 1: // Linked cel.
					cel->is_linked = 1;
					cel->linked_frame_index = s_read_uint16(s);
					break;

				case 2: // Compressed image cel.
				{
					cel->w = s_read_uint16(s);
					cel->h = s_read_uint16(s);
					int zlib_byte0 = s_read_uint8(s);
					int zlib_byte1 = s_read_uint8(s);
					int deflate_bytes = chunk_size - (int)(s->in - chunk_start);
					void* pixels = s->in;
					CUTE_ASEPRITE_ASSERT((zlib_byte0 & 0x0F) == 0x08); // Only zlib compression method (RFC 1950) is supported.
					CUTE_ASEPRITE_ASSERT((zlib_byte0 & 0xF0) <= 0x70); // Innapropriate window size detected.
					CUTE_ASEPRITE_ASSERT(!(zlib_byte1 & 0x20)); // Preset dictionary is present and not supported.
					int pixels_sz = cel->w * cel->h * bpp;
					void* pixels_decompressed = CUTE_ASEPRITE_ALLOC(pixels_sz, mem_ctx);
					int ret = s_inflate(pixels, deflate_bytes, pixels_decompressed, pixels_sz, mem_ctx);
					if (!ret) CUTE_ASEPRITE_WARNING(s_error_reason);
					cel->pixels = pixels_decompressed;
					s_skip(s, deflate_bytes);
				}	break;
				}
				last_udata = &cel->udata;
			}	break;

			case 0x2006: // Cel extra chunk.
			{
				ase_cel_t* cel = frame->cels + frame->cel_count;
				cel->has_extra = 1;
				cel->extra.precise_bounds_are_set = (int)s_read_uint32(s);
				cel->extra.precise_x = s_read_fixed(s);
				cel->extra.precise_y = s_read_fixed(s);
				cel->extra.w = s_read_fixed(s);
				cel->extra.h = s_read_fixed(s);
				s_skip(s, 16); // For future use (set to zero).
			}	break;

			case 0x2007: // Color profile chunk.
			{
				ase->has_color_profile = 1;
				ase->color_profile.type = (ase_color_profile_type_t)s_read_uint16(s);
				ase->color_profile.use_fixed_gamma = (int)s_read_uint16(s) & 1;
				ase->color_profile.gamma = s_read_fixed(s);
				s_skip(s, 8); // For future use (set to zero).
				if (ase->color_profile.type == ASE_COLOR_PROFILE_TYPE_EMBEDDED_ICC) {
					// Use the embedded ICC profile.
					ase->color_profile.icc_profile_data_length = s_read_uint32(s);
					ase->color_profile.icc_profile_data = CUTE_ASEPRITE_ALLOC(ase->color_profile.icc_profile_data_length, mem_ctx);
					CUTE_ASEPRITE_MEMCPY(ase->color_profile.icc_profile_data, s->in, ase->color_profile.icc_profile_data_length);
				}
			}	break;

			case 0x2018: // Tags chunk.
			{
				ase->tag_count = (int)s_read_uint16(s);
				s_skip(s, 8); // For future (set to zero).
				CUTE_ASEPRITE_ASSERT(ase->tag_count < CUTE_ASEPRITE_MAX_TAGS);
				for (int k = 0; k < ase->tag_count; ++k) {
					ase_tag_t tag;
					tag.from_frame = (int)s_read_uint16(s);
					tag.to_frame = (int)s_read_uint16(s);
					tag.loop_animation_direction = (ase_animation_direction_t)s_read_uint8(s);
					s_skip(s, 8); // For future (set to zero).
					tag.r = s_read_uint8(s);
					tag.g = s_read_uint8(s);
					tag.b = s_read_uint8(s);
					s_skip(s, 1); // Extra byte (zero).
					tag.name = s_read_string(s);
					ase->tags[k] = tag;
				}
			}	break;

			case 0x2019: // Palette chunk.
			{
				ase->palette.entry_count = (int)s_read_uint32(s);
				int first_index = s_read_uint32(s);
				int last_index = s_read_uint32(s);
				s_skip(s, 8); // For future (set to zero).
				for (int k = first_index; k <= last_index; ++k) {
					int has_name = s_read_uint16(s);
					ase_palette_entry_t entry;
					entry.color.r = s_read_uint8(s);
					entry.color.g = s_read_uint8(s);
					entry.color.b = s_read_uint8(s);
					entry.color.a = s_read_uint8(s);
					if (has_name) {
						entry.color_name = s_read_string(s);
					} else {
						entry.color_name = NULL;
					}
					ase->palette.entries[k] = entry;
				}
			}	break;

			case 0x2020: // Udata chunk.
			{
				CUTE_ASEPRITE_ASSERT(last_udata);
				int flags = (int)s_read_uint32(s);
				if (flags & 1) {
					last_udata->has_text = 1;
					last_udata->text = s_read_string(s);
				}
				if (flags & 2) {
					last_udata->has_color;
					last_udata->color.r = s_read_uint8(s);
					last_udata->color.g = s_read_uint8(s);
					last_udata->color.b = s_read_uint8(s);
					last_udata->color.a = s_read_uint8(s);
				}
				last_udata = NULL;
			}	break;

			case 0x2022: // Slice chunk.
			{
				int slice_count = s_read_uint32(s);
				int flags = s_read_uint32(s);
				s_skip(s, sizeof(uint32_t)); // Reserved.
				const char* name = s_read_string(s);
				for (int k = 0; k < (int)slice_count; ++k) {
					ase_slice_t slice = { 0 };
					slice.name = name;
					slice.frame_number = (int)s_read_uint32(s);
					slice.origin_x = (int)s_read_int32(s);
					slice.origin_y = (int)s_read_int32(s);
					slice.w = (int)s_read_uint32(s);
					slice.h = (int)s_read_uint32(s);
					if (flags & 1) {
						// It's a 9-patches slice.
						slice.has_center_as_9_slice = 1;
						slice.center_x = (int)s_read_int32(s);
						slice.center_y = (int)s_read_int32(s);
						slice.center_w = (int)s_read_uint32(s);
						slice.center_h = (int)s_read_uint32(s);
					} else if (flags & 2) {
						// Has pivot information.
						slice.has_pivot = 1;
						slice.pivot_x = (int)s_read_int32(s);
						slice.pivot_y = (int)s_read_int32(s);
					}
					CUTE_ASEPRITE_ASSERT(ase->slice_count < CUTE_ASEPRITE_MAX_SLICES);
					ase->slices[ase->slice_count++] = slice;
					last_udata = &ase->slices[ase->slice_count - 1].udata;
				}
			}	break;

			default:
				s_skip(s, chunk_size);
				break;
			}
		}
	}

	// Blend all cel pixels into each of their respective frames, for convenience.
	for (int i = 0; i < ase->frame_count; ++i) {
		ase_frame_t* frame = ase->frames + i;
		frame->pixels = (ase_color_t*)CUTE_ASEPRITE_ALLOC(sizeof(ase_color_t) * ase->w * ase->h, mem_ctx);
		CUTE_ASEPRITE_MEMSET(frame->pixels, 0, sizeof(ase_color_t) * ase->w * ase->h);
		ase_color_t* dst = frame->pixels;
		for (int j = 0; j < frame->cel_count; ++j) {
			ase_cel_t* cel = frame->cels + j;
			if (!(cel->layer->flags & ASE_LAYER_FLAGS_VISIBLE)) {
				continue;
			}
			while (cel->is_linked) {
				cel = ase->frames[cel->linked_frame_index].cels + j;
			}
			void* src = cel->pixels;
			uint8_t opacity = (uint8_t)(cel->opacity * cel->layer->opacity * 255.0f);
			int cx = cel->x;
			int cy = cel->y;
			int cw = cel->w;
			int ch = cel->h;
			int cl = -s_min(cx, 0);
			int ct = -s_min(cy, 0);
			int dl = s_max(cx, 0);
			int dt = s_max(cy, 0);
			int dr = s_min(ase->w, cw + cx);
			int db = s_min(ase->h, ch + cy);
			int aw = ase->w;
			for (int dx = dl, sx = cl; dx < dr; dx++, sx++) {
				for (int dy = dt, sy = ct; dy < db; dy++, sy++) {
					int dst_index = aw * dy + dx;
					ase_color_t src_color = s_color(ase, src, cw * sy + sx);
					ase_color_t dst_color = dst[dst_index];
					ase_color_t result = s_blend(src_color, dst_color, opacity);
					dst[dst_index] = result;
				}
			}
		}
	}

	ase->mem_ctx = mem_ctx;
	return ase;
}

void cute_aseprite_free(ase_t* ase)
{
	for (int i = 0; i < ase->frame_count; ++i) {
		ase_frame_t* frame = ase->frames + i;
		CUTE_ASEPRITE_FREE(frame->pixels, ase->mem_ctx);
		for (int j = 0; j < frame->cel_count; ++j) {
			ase_cel_t* cel = frame->cels + j;
			CUTE_ASEPRITE_FREE(cel->pixels, ase->mem_ctx);
			CUTE_ASEPRITE_FREE((void*)cel->udata.text, ase->mem_ctx);
		}
	}
	for (int i = 0; i < ase->layer_count; ++i) {
		ase_layer_t* layer = ase->layers + i;
		CUTE_ASEPRITE_FREE((void*)layer->name, ase->mem_ctx);
		CUTE_ASEPRITE_FREE((void*)layer->udata.text, ase->mem_ctx);
	}
	for (int i = 0; i < ase->tag_count; ++i) {
		ase_tag_t* tag = ase->tags + i;
		CUTE_ASEPRITE_FREE((void*)tag->name, ase->mem_ctx);
	}
	for (int i = 0; i < ase->slice_count; ++i) {
		ase_slice_t* slice = ase->slices + i;
		CUTE_ASEPRITE_FREE((void*)slice->udata.text, ase->mem_ctx);
	}
	if (ase->slice_count) {
		CUTE_ASEPRITE_FREE((void*)ase->slices[0].name, ase->mem_ctx);
	}
	for (int i = 0; i < ase->palette.entry_count; ++i) {
		CUTE_ASEPRITE_FREE((void*)ase->palette.entries[i].color_name, ase->mem_ctx);
	}
	CUTE_ASEPRITE_FREE(ase->color_profile.icc_profile_data, ase->mem_ctx);
	CUTE_ASEPRITE_FREE(ase->frames, ase->mem_ctx);
	CUTE_ASEPRITE_FREE(ase, ase->mem_ctx);
}

#endif // CUTE_ASEPRITE_IMPLEMENTATION_ONCE
#endif // CUTE_ASEPRITE_IMPLEMENTATION

/*
	------------------------------------------------------------------------------
	This software is available under 2 licenses - you may choose the one you like.
	------------------------------------------------------------------------------
	ALTERNATIVE A - zlib license
	Copyright (c) 2017 Randy Gaul http://www.randygaul.net
	This software is provided 'as-is', without any express or implied warranty.
	In no event will the authors be held liable for any damages arising from
	the use of this software.
	Permission is granted to anyone to use this software for any purpose,
	including commercial applications, and to alter it and redistribute it
	freely, subject to the following restrictions:
	  1. The origin of this software must not be misrepresented; you must not
	     claim that you wrote the original software. If you use this software
	     in a product, an acknowledgment in the product documentation would be
	     appreciated but is not required.
	  2. Altered source versions must be plainly marked as such, and must not
	     be misrepresented as being the original software.
	  3. This notice may not be removed or altered from any source distribution.
	------------------------------------------------------------------------------
	ALTERNATIVE B - Public Domain (www.unlicense.org)
	This is free and unencumbered software released into the public domain.
	Anyone is free to copy, modify, publish, use, compile, sell, or distribute this
	software, either in source code form or as a compiled binary, for any purpose,
	commercial or non-commercial, and by any means.
	In jurisdictions that recognize copyright laws, the author or authors of this
	software dedicate any and all copyright interest in the software to the public
	domain. We make this dedication for the benefit of the public at large and to
	the detriment of our heirs and successors. We intend this dedication to be an
	overt act of relinquishment in perpetuity of all present and future rights to
	this software under copyright law.
	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 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.
	------------------------------------------------------------------------------
*/