kernel.c

   1 extern unsigned int _sram_end;
   2 extern unsigned int _data_vma_start;
   3 extern unsigned int _data_vma_end;
   4 extern unsigned int _data_lma_start;
   5 extern unsigned int _bss_vma_start;
   6 extern unsigned int _bss_vma_end;
   7
   8 #define RCC_AHB1 ((volatile unsigned int * const) 0x40023830)
   9 #define GPIOC_MODER ((volatile unsigned int * const) 0x40020800)
  10 #define GPIOC_ODR ((volatile unsigned int * const) 0x40020814)
  11
  12 static void
  13 delay (void)
  14 {
  15   volatile unsigned int i;
  16   for (i = 0; i < 500000; i++);
  17 }
  18
  19 static void
  20 reset_handler (void)
  21 {
  22   unsigned int *src, *dst;
  23
  24   /* relocate .data to sram  */
  25   src = &_data_lma_start;
  26   dst = &_data_vma_start;
  27
  28   while (dst < &_data_vma_end)
  29     *(dst++) = *(src++);
  30
  31   /* initialize .bss  */
  32   dst = &_bss_vma_start;
  33
  34   while (dst < &_bss_vma_end)
  35     *(dst++) = 0;
  36
  37   /* blink blink  */
  38   *RCC_AHB1 |= (1u << 2);
  39   *GPIOC_MODER &= ~(3u << 26);
  40   *GPIOC_MODER |= (1u << 26);
  41
  42   while (1)
  43     {
  44       *GPIOC_ODR ^= (1u << 13);
  45       delay ();
  46     }
  47 }
  48
  49 __attribute__ ((section (".vtbl"), used))
  50 static unsigned long const vector_table[] = {
  51   (unsigned long) &_sram_end,
  52   (unsigned long) reset_handler,
  53 };