#include <stdio.h>

void readdec(int *, int *) ;
int prnthex(int) ;

int main(int argc, char *arvg[], char *envp[]) {
  int R0, R1, R2, R3 ;

  fputs("Enter a postive decimal number> ", stdout) ;

  /* Read in the integer as a decimal */
  R2 = 0 ;
  while (1) {
    readdec(&R0, &R1) ;
    if (R0 < 0)
      break ;
    R2 = 10*R2 + R1 ;
  }

  fputs("\nIn hexadecimal your number is ", stdout) ;
  for (R3=4; R3>0; --R3) {
    R0 = R2 >> 12 ;	/* Hard to do in the LC-2 */
    R0 = prnthex(R0) ;
    putc(R0, stdout) ;
    R2 = R2<<4 ;
  }
  putc('\n', stdout) ;
}