Merge branch 'master' into stack-debug

Makefile

@@ -13,6 +13,7 @@ SRC          = \
 	main.c \
 	ftdi.c \
         reset.c \
+	stack.c \
 	$(LUFA_SRC_USB)
 
 # Default target

main.c

@@ -9,6 +9,7 @@
 #include <LUFA/Drivers/USB/USB.h>
 
 #include "ftdi.h"
+#include "stack.h"
 
 static void setup(void)
 {
@@ -36,7 +37,10 @@ int main(void)
 		c = getchar();
 		/* If FTDI_NONBLOCKING was provided to ftdi_init,
 		   c will be -1 if no data was available. */
-		if (c >= 0)
+		if (c >= 0) {
 			printf("You sent %d (%c)\n", c, isprint(c) ? c : '?');
+			printf("Maximum stack space used: %d / %d bytes\n",
+			       (stack_total() - stack_min()), stack_total());
+		}
 	}
 }

stack.c

@@ -0,0 +1,46 @@
+#include "stack.h"
+#include <stdint.h>
+#include <avr/interrupt.h>
+
+extern uint8_t _end;
+extern uint8_t __stack;
+
+void __stack_canary_init(void)
+	__attribute__ ((naked))
+	__attribute__ ((section (".init1")));
+void __stack_canary_init(void)
+{
+	__asm volatile ("    ldi r30,lo8(_end)\n"
+			"    ldi r31,hi8(_end)\n"
+			"    ldi r24,lo8(0xaa)\n" // canary
+			"    ldi r25,hi8(__stack)\n"
+			"    rjmp 2f\n"
+			"1:\n"
+			"    wdr\n"
+			"    st Z+,r24\n"
+			"2:\n"
+			"    cpi r30,lo8(__stack)\n"
+			"    cpc r31,r25\n"
+			"    brlo 1b\n"
+			"    breq 1b"
+			:
+			:
+			: "memory");
+}
+
+/* return low level mark of free stack space */
+uint16_t stack_min(void)
+{
+	const uint8_t *p;
+	uint16_t c = 0;
+
+	for (p = &_end; *p == 0xaa && p <= &__stack; p++)
+		c++;
+	return c;
+}
+
+/* return total amount of stack */
+uint16_t stack_total(void)
+{
+	return &__stack - &_end;
+}

stack.h

@@ -0,0 +1,12 @@
+#ifndef STACK_H
+#define STACK_H
+
+#include <stdint.h>
+
+/* return low level mark of free stack space */
+uint16_t stack_min(void);
+
+/* return total amount of stack */
+uint16_t stack_total(void);
+
+#endif