embedded-game-programming/tools/src/palette_processor.c

#include <assert.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char** argv)
{
	if (argc != 3)
	{
		fprintf(stderr, "Usage: %s <input palette> <output header>\n", argv[0]);

		return 1;
	}

	const char* inFilename = argv[1];
	const char* outFilename = argv[2];

	// Read the file
	uint16_t* palette;
	int paletteSize;
	{
		FILE* inFile = fopen(inFilename, "r");
		assert(inFile);

		char* line;
		size_t len = 0;

		getline(&line, &len, inFile);
		assert(strncmp(line, "JASC-PAL", 8) == 0);

		getline(&line, &len, inFile);
		assert(strncmp(line, "0100", 4) == 0);

		getline(&line, &len, inFile);
		paletteSize = atoi(line);

		palette = malloc(sizeof(*palette) * paletteSize);
		assert(palette);

		// Each line is of form R G B
		for (int i = 0; i < paletteSize; ++i)
		{
			getline(&line, &len, inFile);

			char* tok = strtok(line, " ");
			int red = atoi(tok);

			tok = strtok(NULL, " ");
			int green = atoi(tok);

			tok = strtok(NULL, " ");
			int blue = atoi(tok);

			uint16_t rgb565 =
				  ((red >> 3u) << 11u)
				| ((green >> 2u) << 5u)
				| (blue >> 3u);

			uint16_t endianSwap = ((rgb565 & 0xFFu) << 8u) | (rgb565 >> 8u);

			palette[i] = endianSwap;
		}

		fclose(inFile);
	}


	printf("Input: %s\n", inFilename);
	printf("Output: %s\n", outFilename);
	printf("Palette Size: %d\n", paletteSize);


	// Output to the file
	{
		FILE* outFile = fopen(outFilename, "w");
		assert(outFile);

		fprintf(outFile, "// AUTOMATICALLY GENERATED. DO NOT EDIT.\n");
		fprintf(outFile, "\n");
		fprintf(outFile, "#pragma once\n");
		fprintf(outFile, "\n");
		fprintf(outFile, "\n");

		fprintf(outFile, "uint16_t palette[%d] =\n", paletteSize);
		fprintf(outFile, "{\n");

		for (int i = 0; i < paletteSize; ++i)
		{
			fprintf(outFile, "	0x%04X,\n", palette[i]);
		}

		fprintf(outFile, "};\n");
		fprintf(outFile, "\n");

		fclose(outFile);
	}

	printf("\n");
	printf("DONE\n");


	return 0;
}