Blink LED with spin function

src/main.c

@@ -1,5 +1,23 @@
+#include <inttypes.h>
+#include "rcc.h"
+#include "gpio.h"
+
 #define exit 42
 
+static inline void spin(volatile uint32_t count) {
+  while (count--) (void) 0;
+}
+
 int main(void) {
+  uint16_t led = PIN('C', 13);           // Blue LED
+  RCC->AHB1ENR |= BIT(PINPORT(led));     // Enable GPIO clock for LED
+  gpio_set_mode(led, GPIO_MODE_OUTPUT);  // Set blue LED to output mode
+  for (;;) {
+    gpio_write(led, true);
+    spin(999999);
+    gpio_write(led, false);
+    spin(999999);
+  };
+
   return exit;
 }