#include <stdio.h>
#include <stdlib.h>

/* cc ulzdec.c -o ulzdec && ./ulzdec compressed.bin */

static int
error(const char *name, const char *msg)
{
	fprintf(stderr, "%s: %s\n", name, msg);
	return 0;
}

void
decode_byte(FILE *fp, char *res, unsigned char c)
{
	if(c & 0x80) {
		if(c & 0x40) { /* DICT3 */
			unsigned short length = ((c & 0x3f) << 8 | getc(fp)) + 4;
			unsigned char offset = getc(fp) + 1;
			printf("DIC3  %04x, %02x\n", length, offset);
		} else { /* DICT2 */
			unsigned char length = (c & 0x3f) + 4;
			unsigned char offset = getc(fp) + 1;
			printf("DIC1  %02x, %02x\n", length, offset);
		}
	} else { /* LIT */
		unsigned char i, length = c + 1;
		printf("LIT%02x ", length);
		for(i = 0; i < length; ++i) {
			unsigned char c2 = getc(fp);
			printf("%c", c2 == '\n' ? ' ' : c2);
		}
		printf("\n");
	}
}

int
main(int argc, char *argv[])
{
	char c, *res;
	FILE *src;
	if(argc == 2 && argv[1][0] == '-' && argv[1][1] == 'v')
		return !fprintf(stdout, "Ulzdec - ULZ Decoder, 15 Nov 2023.\n");
	if(argc != 2)
		return error("usage", "ulzdec [-v] compressed.bin");
	if(!(src = fopen(argv[1], "rb")))
		return !error("Invalid input", argv[1]);
	res = malloc(0x10000);
	while((c = getc(src)) != EOF)
		decode_byte(src, res, c);
	return 0;
}