#include <stdio.h>
/* for setting serial baudrate */
__sfr __at 0X89 TMOD;
__sfr __at 0x98 SCON;
__sfr __at 0x8D TH1;
__sbit __at 0x8E TR1; /** TCON.6 */

/* for serial transmit */
__sfr __at 0x99 SBUF;
__sbit __at 0x98 RI; /** SCON.0 */
__sbit __at 0x99 TI; /** SCON.1 */

/* SDCC printf needs this to be defined */
void putchar(char c)
{
    SBUF = c;
    while (!TI);
    TI = 0;
}

/* SDCC gets (no scanf) needs this to be defined */
char getchar(void)
{
    char c;
    while(!RI);
    c = SBUF;
    RI = 0;
    return c;
}

#define NAME_SIZE_MAX 16
#define BUFF_SIZE_MAX 4
#define THIS_YEAR 2013

char name[NAME_SIZE_MAX], buff[BUFF_SIZE_MAX];
int year, age;

int convert_int(char* buff)
{
    int calc = 0, length = 0, mult = 1;
    /** get string length */
    while(buff[length]) length++;
    /** browse through the array - from right! */
    while(length>0)
    {
        length--;
        /** check if really numeric */
        if(buff[length]<0x30||buff[length]>0x39)
            return 0;
        /** get digit actual value */
        calc = calc + (buff[length]-0x30)*mult;
        /** prepare next iteration */
        mult = mult * 10;
    }
    return calc;
}

/* main function */
void main()
{
    TMOD = 0x21; SCON = 0x50; TH1 = 253; TR1 = 1;
    while(1)
    {
        /** get user input */
        printf("Enter name [MAX=%d]: ",NAME_SIZE_MAX);
        gets(name);
        printf("Enter your age (Max=99): ");
        gets(buff);
        /** process year of birth */
        age = convert_int(buff);
        year = THIS_YEAR - age;
        /** display */
        printf("Hi, %s! You were born in %d\n",name,year); 
    }
}