avr/stackusage.c

   1 /* Code to measure the stack usage.
   2  * Copied from http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&p=343692
   3  */
   4
   5 #include <stdint.h>
   6 #include "stackusage.h"
   7
   8 #define STACK_CANARY 0xc5
   9
  10 extern uint8_t _end;
  11 extern uint8_t __stack;
  12
  13 void paint_stack(void)
  14         __attribute__ ((naked))
  15         __attribute__ ((used))
  16         __attribute__ ((section (".init1")));
  17
  18 void paint_stack(void)
  19 {
  20 #if 0
  21     uint8_t *p = &_end;
  22
  23     while(p <= &__stack)
  24     {
  25         *p = STACK_CANARY;
  26         p++;
  27     }
  28 #else
  29     __asm volatile ("    ldi r30,lo8(_end)\n"
  30                     "    ldi r31,hi8(_end)\n"
  31                     "    ldi r24,lo8(0xc5)\n" /* STACK_CANARY = 0xc5 */
  32                     "    ldi r25,hi8(__stack)\n"
  33                     "    rjmp .cmp\n"
  34                     ".loop:\n"
  35                     "    st Z+,r24\n"
  36                     ".cmp:\n"
  37                     "    cpi r30,lo8(__stack)\n"
  38                     "    cpc r31,r25\n"
  39                     "    brlo .loop\n"
  40                     "    breq .loop"::);
  41 #endif
  42 }
  43
  44 uint16_t stack_usage(void)
  45 {
  46     const uint8_t *p = &_end;
  47     uint16_t       c = 0;
  48
  49     while(*p == STACK_CANARY && p <= &__stack)
  50     {
  51         p++;
  52         c++;
  53     }
  54
  55     return &__stack - &_end - c;
  56 }