mem-check.c

/*
   Licensed under the EUPL V.1.1, Lizenziert unter EUPL V.1.1 
*/
#include <avr/io.h>  // RAMEND
#include "mem-check.h"

// Mask to init SRAM and check against
#define MASK 0xaa

// From linker script
extern unsigned char __heap_start;

uint16_t get_mem_free( void )
{
	return SP - (uint16_t) &__heap_start;
}

unsigned short get_mem_unused( void )
{
	unsigned short unused = 0;
	unsigned char *p = &__heap_start;

	do
	{
		if ( *p++ != MASK ) break;

		unused++;
	} while ( p <= (unsigned char*) RAMEND );

	return unused;
}

/* !!! never call this function !!! */
void __attribute__ ((naked, section(".init3"))) init_mem( void );
void init_mem( void )
{
	__asm volatile (
			"ldi r30, lo8 (__heap_start)" "\n\t"
			"ldi r31, hi8 (__heap_start)" "\n\t"
			"ldi r24, %0" "\n\t"
			"ldi r25, hi8 (%1)" "\n"
			"0:" "\n\t"
			"st  Z+,  r24" "\n\t"
			"cpi r30, lo8 (%1)" "\n\t"
			"cpc r31, r25" "\n\t"
			"brlo 0b"
			:
			: "i" (MASK), "i" (RAMEND+1)
	);
}