An inefficient compression algorithm

main.c

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

int main(int argc, char *argv[])
{
	if (argc != 3)
		return 1;
	int seq_size = atoi(argv[1]);
	int repeat = atoi(argv[2]);

	uint8_t seq[seq_size];
	int c, i = 0;
	uint16_t w = 0;
	while ((c = getchar()) >= 0) {
		int idx = i % seq_size;
		int rep = i / seq_size;
		i++;
		if (rep != repeat) {
			// Not yet repeated
			putchar(c);
			// Reset if mismatched
			if (rep && c != seq[idx])
				i -= seq_size * rep;
			seq[idx] = c;
		} else if (c != seq[idx] || w == (uint16_t)-1) {
			// Sequence mismatched or counter about to overflow
			seq[idx] = c;
			// Write counter and sequence then reset
			fwrite(&w, sizeof(w), 1, stdout);
			fwrite(seq, 1, idx + 1, stdout);
			i -= seq_size * repeat;
			w = 0;
		} else if (!(i % seq_size)) {
			// Sequence matched
			i -= seq_size;
			w++;
		}
	}

	// End-of-file
	int idx = i % seq_size;
	int rep = i / seq_size;
	if (rep == repeat) {
		// Sequence repeated, write counter and remaining data
		fwrite(&w, sizeof(w), 1, stdout);
		fwrite(seq, 1, idx, stdout);
	}
	return 0;
}

Great~