#include "mem.h"
#include "io.h"


void
initmem(unsigned int memstart)
{
	unsigned int* p;
	int step = 2*1024*1024;
	unsigned int* zero = 0x0;


	minmem = (unsigned char*)memstart;

	/* disable cache */
	__asm__ __volatile__ (
		"movl %cr0, %eax\n\t"
		"movl $0x60000000, %ebx\n\t"
		"orl %ebx, %eax\n\t"
		"movl %eax, %cr0"
	);

	/* test mem size */
	p = (unsigned int*) ((unsigned int)minmem/sizeof(char));
	do {
		p += step;
		*p = 0xf0f0f0f0;
	} while (*p == 0xf0f0f0f0);
	maxmem = (unsigned char*)p;

	/* test mem mirroring */
	p = 0;
	*p = 0;
	p++;
	while (p < (unsigned int*)minmem) {
		p = (unsigned int*) ((unsigned int)p * 2);
	}
	while (p < (unsigned int*)maxmem) {
		*p = 0xf0f0f0f0;
		if (*zero == 0xf0f0f0f0) {
			maxmem = (unsigned char*)p;
			break;
		}
		p = (unsigned int*) ((unsigned int)p * 2);
	}

	/* enable cache again */
	__asm__ __volatile__ (
		"movl %cr0, %eax\n\t"
		"movl $0x60000000, %ebx \n\t"
		"negl %ebx\n\t"
		"andl %ebx, %eax\n\t"
		"movl %eax, %cr0"
	);

	/* min, max */
	printf("mem: start=%p end=%p size=%p\n", minmem, maxmem, (void*)(maxmem-minmem));

	/* init heap */
	newp = minmem;
}


void*
malloc(unsigned int size)
{
	if (newp + size > maxmem) {
		printf("Fatal error: memory exhausted!\n");
		while (1) {
		}
	}
	newp += size;
	return newp - size;
}