CMOS fun for boring days

gistfile1.c

#include <stdio.h>
#include <sys/io.h>

int convert_bcd (unsigned char bcd) {
    return (bcd >> 4) * 10 + (bcd & 0xF);
}

unsigned char cmos_read (int offset) {
    outb(0x80 | (offset & 0x7F), 0x70);
    return inb(0x71);
}

int main (int argc, char **argv) {
/*    int i, offset;*/
/*    if (argc < 2)*/
/*        return 1;    */
    ioperm(0x70, 2, 1);
/*    for (i = 1; i < argc; i++) {*/
/*        printf("%02x\n", cmos_read(atoi(argv[i])));*/
/*    }*/
    if (cmos_read(0xA) & 0x80) {
        printf("Could not fetch the time, the RTC is in update stage\n");
        return 1;
    }
    printf("%02i:%02i:%02i %02i/%02i/%04i\n", 
        convert_bcd(cmos_read(4)),
        convert_bcd(cmos_read(2)),
        convert_bcd(cmos_read(0)),
        
        convert_bcd(cmos_read(7)),
        convert_bcd(cmos_read(8)),
        convert_bcd(cmos_read(9)) + 2000
    );
    ioperm(0x70, 2, 0);
    return 0;
}