#include <reg51.h>

typedef unsigned char uint8_t;
typedef unsigned int uint16_t;

uint16_t fd2b( uint16_t x ) {
    // Multiplyng for considering sign.
    return (((((x&0x70)>>4)*10+(x&0x0f))<<8)/100)*(x&0x80?-1:1);
}

uint16_t fb2d( uint16_t x ) {
    // FOr considering sign.
    uint8_t mask = x&0x80 ? 0x80 : 0;
    x *= 10;
    return ((x&0x700)>>4)|((((x&0xff)*10)&0xf00)>>8)|mask;
}

main( ) {
    uint16_t num = fd2b(P0);
    P1 = fd2b(num);
    // For testing.
    P2 = num;
    while(1);
}