Workaround gotoxy() kernel crash in C64 open source BIOS

xygoto.c

#include <stdio.h>
#include <conio.h>
#include <c64.h>
#include <cbm_petscii_charmap.h>

void xygoto(char x, char y) {
  x=x; y=y; // to avoid "unused variable" warning
  __asm__ ("jsr popa");
  __asm__ ("tax");	 // pop X
  __asm__ ("jsr popa");
  __asm__ ("tay");	 // pop Y
  __asm__ ("clc");
  __asm__ ("jsr $fff0"); // call PLOT kernal routine
}

void main(void) {
  clrscr();

  printf("\r\nHello World! Press a key ...\r\n");
  cgetc();
  cputs("Print next line");
  xygoto(15,5);
  cputs("Print @ 15,5");
  xygoto(16,6);
  cputs("Print @ 16,6");
  
  while (1) ;
}