multiboot.c

一个微型操作系统源码

/*
 * OSV
 * Copyright (C) 2002 Ciprian DOSOFTEI <[e-mail]>
 * All rights reserved.
 * 
 * http://backster.free.fr/osv
 *
 * This file is part of the OSV project. OSV is free software, also known as
 * "open source"; you can redistribute it and/or modify it under the terms 
 * of the GNU General Public License (GPL), version 2, as published by the Free
 * Software Foundation (FSF). To explore alternate licensing terms, contact 
 * the author at [e-mail] or [phone].
 * 
 * OSV is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GPL for more details.  You should have
 * received a copy of the GPL along with OSV; see the file COPYING.  If
 * not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
 */

#include <multiboot.h>

ulong get_available_memory(mb_info_t *bootInfo) {
    if (bootInfo->flags & MULTIBOOT_MEMORY) {
	return (ulong)((bootInfo->mem_upper + 1024) << 10); 
    } else {
	halt();
    }
}

ulong get_used_memory(mb_info_t *bootInfo) {
    int i;
    extern void _end;
    dword top = (ulong)&_end;

    if (bootInfo->flags & MULTIBOOT_MODS) {
        for (i=0; i<bootInfo->mod_count; i++)
    	    if (bootInfo->modules[i].end > top)
        	top = bootInfo->modules[i].end;
    }

    top = (top + 4095) & 0xFFFFF000;
    return (ulong)top;
}