#ifndef cpu_sr
#define ENTER_CRITICAL()  unsigned short cpu_sr; __asm __volatile__ ("tpa\n sei\n" : "=d"(cpu_sr))  
#else
#define ENTER_CRITICAL()  __asm __volatile__ ("tpa\n sei\n" : "=d"(cpu_sr))
#endif

#define EXIT_CRITICAL()   __asm __volatile__ ("tap\n" : : "d"(cpu_sr))