#include <reg51.h>

unsigned char converte_7seg (unsigned char);

void main (void) {
    unsigned char le_p2, i, cnt_closed;
    P0 = 0x80;
    P3 = 0xEF;

    while (1) {
        le_p2 = ~P2;
	cnt_closed = 0;
	for (i = 0; i < 8; i++) {
	    if (le_p2&0x80) cnt_closed++;
	    le_p2 <<= 1;
	}
        P1 = converte_7seg(cnt_closed);
    }
}

unsigned char converte_7seg (unsigned char dado) {
    switch (dado) {
        case  0: return 0x40;
        case  1: return 0x79;
        case  2: return 0x24;
        case  3: return 0x30;
        case  4: return 0x19;
        case  5: return 0x12;
        case  6: return 0x02;
        case  7: return 0x78;
        case  8: return 0x00;
        case  9: return 0x10;
        case 10: return 0x08;
        case 11: return 0x03;
        case 12: return 0x46;
        case 13: return 0x21;
        case 14: return 0x06;
        case 15: return 0x0E;
        default: return 0x80;
    }
}