libpoker.c

unsigned char score(struct card *cards) {
	if (cards[0].value == cards[1].value
	    && cards[0].value == cards[2].value
	    && cards[0].value == cards[3].value) {
		return RANK_FOUR;
	}

	unsigned char order[] = {0, 1, 2, 3};
	unsigned char swapped;
	do {
		swapped = 0;
		unsigned char i;
		for (i = 1; i < 4; i++) {
			if (cards[order[i-1]].value > cards[order[i]].value) {
				unsigned char tmp = order[i];
				order[i] = order[i-1];
				order[i-1] = tmp;
				swapped = 1;
			}
		}
	} while (swapped);

	unsigned char flush = 0;
	if (cards[0].suit == cards[1].suit
	    && cards[0].suit == cards[2].suit
	    && cards[0].suit == cards[3].suit) {
		flush = 1;
	}

	unsigned char straight = 0;
	if (cards[ordered[0]].value+1 == cards[ordered[1]]
	    && cards[ordered[0]].value+2 == cards[ordered[2]]
	    && cards[ordered[0]].value+3 == cards[ordered[3]]) {
		straight = 1;
	}

	if (flush && straight) {
		return RANK_STRAIGHT_FLUSH;
	}

	if (!straight) {
		/* test for three kind, two pair, one pair */
		if (cards[ordered[1]].value == cards[ordered[2]].value
		    && (cards[ordered[0]].value == cards[ordered[1]].value
			|| cards[ordered[3]].value == cards[ordered[1]].value)) {
			return RANK_THREE;
		}
		if (cards[ordered[0]].value == cards[ordered[1]].value
		    && cards[ordered[2]].value == cards[ordered[3]].value) {
			return RANK_TWO;
		}
		if (cards[ordered[0]].value == cards[ordered[1]].value
		    || cards[ordered[1]].value == cards[ordered[2]].value
		    || cards[ordered[2]].value == cards[ordered[3]].value) {
			return RANK_PAIR;
		}
	} else if (flush) {
		return RANK_FLUSH;
	} else {
		return RANK_STRAIGHT;
	}

	return RANK_HIGH;
}