ASCIIART benchmark, C translated

// original BASIC code at https://www.retrobrewcomputers.org/forum/index.php?t=msg&th=201&goto=4704&#msg_4704
// translated C code, CC0

#include <stdio.h>

int main(int argc, char *argv[])
{
	int x, y, i;
	float a, b, ca, cb, t;
	const static unsigned char c[] = "0123456789ABCDEF ";

	for (y = -12; y <= 12; y++) {
		for (x = -39; x <= 39; x++) {
			a = ca = x * 0.0458;
			b = cb = y * 0.08333;

			for (i = 0; i <= 15; i++) {
				t = (a * a) - (b * b) + ca;
				b = (2 * a * b) + cb;
				a = t;

				if ((a * a + b * b) > 4)
					break;
			}
			putchar(c[i]);
		}

		putchar('\n');
	}

	return 0;
}