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#include <stdlib.h>
#include <stdio.h>
#include <byteswap.h>
#include <inttypes.h>
#include "qoi.h"
#include "image.h"
#define MONS_QOI_RGB 3
#define MONS_QOI_RGBA 4
#define MONS_QOI_SRGB_LINEAR_ALPHA 0
#define MONS_QOI_LINEAR 1
#define MONS_QOI_HEADER_LEN 14
#define MONS_QOI_OP_RGB 0b11111110
#define MONS_QOI_OP_RGBA 0b11111111
#define MONS_QOI_OP_INDEX 0b00000000
#define MONS_QOI_OP_DIFF 0b01000000
#define MONS_QOI_OP_LUMA 0b10000000
#define MONS_QOI_OP_RUN 0b11000000
typedef struct mons_qoi_header {
char magic[4];
uint32_t width;
uint32_t height;
uint8_t channels;
uint8_t colorspace;
} mons_qoi_header;
unsigned char pixel_index_hash(mons_pixel pixel) {
return (pixel.r * 3 + pixel.g * 5 + pixel.b * 7 + pixel.a * 11) % 64;
}
mons_image mons_load_qoi(FILE *stream) {
mons_qoi_header header;
if (fread(&header, MONS_QOI_HEADER_LEN, 1, stream) != 1) {
fprintf(stderr, "Error reading QOI header");
return (mons_image){0};
}
header.width = __bswap_32(header.width);
header.height = __bswap_32(header.height);
mons_pixel previous = {0, 0, 0, 255};
mons_pixel previously_seen[64] = {0};
mons_image output = {
.width = header.width,
.height = header.height,
.data = calloc(4, header.width * header.height),
};
for (size_t i = 0; i < header.width * header.height; i++) {
unsigned char op;
if (fread(&op, 1, 1, stream) != 1) {
fprintf(stderr, "Failed reading operation byte!");
return (mons_image){0};
}
switch (op) {
case MONS_QOI_OP_RGB: {
unsigned char rgb[3];
if (fread(&rgb, 1, 3, stream) != 3) {
fprintf(stderr, "Failed reading RGB data!");
return (mons_image){0};
}
output.data[i] = (mons_pixel){
.r = rgb[0],
.g = rgb[1],
.b = rgb[2],
.a = previous.a,
};
break;
}
case MONS_QOI_OP_RGBA: {
unsigned char rgba[4];
if (fread(&rgba, 1, 4, stream) != 4) {
fprintf(stderr, "Failed reading RGBA data!");
return (mons_image){0};
}
output.data[i] = (mons_pixel){
.r = rgba[0],
.g = rgba[1],
.b = rgba[2],
.a = rgba[3],
};
break;
}
default:
switch (op & 0b11000000) {
case MONS_QOI_OP_INDEX: {
unsigned char index = op & 0b00111111;
output.data[i] = previously_seen[index];
break;
}
case MONS_QOI_OP_DIFF: {
char r_diff = ((op & 0b00110000) >> 4) - 2;
char g_diff = ((op & 0b00001100) >> 2) - 2;
char b_diff = (op & 0b00000011) - 2;
output.data[i] = (mons_pixel){
.r = previous.r + r_diff,
.g = previous.g + g_diff,
.b = previous.b + b_diff,
.a = previous.a,
};
break;
}
case MONS_QOI_OP_LUMA: {
int g_diff = (op & 0b00111111) - 32;
unsigned char second_byte;
if (fread(&second_byte, 1, 1, stream) != 1) {
fprintf(stderr,
"Failed to read second byte of luma operation!");
return (mons_image){0};
}
int r_diff = g_diff - 8 + (((second_byte & 0b11110000) >> 4));
int b_diff = g_diff - 8 + (second_byte & 0b00001111);
output.data[i] = (mons_pixel){
.r = previous.r + r_diff,
.g = previous.g + g_diff,
.b = previous.b + b_diff,
.a = previous.a,
};
break;
}
case MONS_QOI_OP_RUN: {
unsigned char run = (op & 0b00111111) + 1;
for (int j = 0; j < run; j++) {
output.data[i++] = previous;
}
i--;
break;
}
default:
break;
}
break;
}
previous = output.data[i];
unsigned int hash = pixel_index_hash(output.data[i]);
previously_seen[hash] = output.data[i];
}
fclose(stream);
return output;
}
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