// **** libc ****
void delay(int a) {
volatile int i;
for (i = 0; i < a; i++);
}
void *memset(void *str, int c, unsigned int n) {
uint8_t *s = str;
for (unsigned int i = 0; i < n; i++) {
*s = c;
s++;
return str;
void *memcpy(void *dest, const void *src, unsigned int n) {
uint8_t *d = dest;
const uint8_t *s = src;
*d = *s;
d++;
return dest;
int memcmp(const void * ptr1, const void * ptr2, unsigned int num) {
int ret = 0;
const uint8_t *p1 = ptr1;
const uint8_t *p2 = ptr2;
for (unsigned int i = 0; i < num; i++) {
if (*p1 != *p2) {
ret = -1;
break;
p1++;
p2++;
return ret;
// ********************* IRQ helpers *********************
int interrupts_enabled = 0;
void enable_interrupts(void) {
interrupts_enabled = 1;
__enable_irq();
int critical_depth = 0;
void enter_critical_section(void) {
__disable_irq();
// this is safe because interrupts are disabled
critical_depth += 1;
void exit_critical_section(void) {
critical_depth -= 1;
if ((critical_depth == 0) && interrupts_enabled) {