Ext2-Filesystem/alloc_dalloc.c at main · Gerola/Ext2-Filesystem · GitHub

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//Allocating the data and the inodes
//-----------------functions in this file-----------------
// tst_bit,set_bit,decFreeInodes,ialloc,balloc,decFreeBlocks

int tst_bit(char* buf, int bit)
{
	return buf[bit/8] & (1 << (bit%8));

}

int set_bit(char* buf, int bit)
{
	buf[bit/8] |= (1 << (bit % 8));
}


//Keep track of the nodes that are free
int decFreeInodes(int dev)
{
	char buf[BLKSIZE];
	get_block(dev,1,buf);
	sp = (SUPER*)buf;
	sp->s_free_inodes_count--;
	put_block(dev,1,buf);

	get_block(dev,2,buf);
	gp = (GD*)buf;
	gp->bg_free_inodes_count--;
	put_block(dev,2,buf);
}

int ialloc(int dev)
{
	int i;
	char buf[BLKSIZE];

	get_block(dev,imap,buf);
	for(i=0;i<ninodes;i++)
	{
		if(tst_bit(buf,i) == 0)
		{
			set_bit(buf,i);
			put_block(dev,imap,buf);
			decFreeInodes(dev);

			printf("Allocated ino = %d\n",i+1);
			return i+1;//inodes goes from 1 not 0
		}
	}

	return 0;
}


int balloc(int dev)
{
	int i;
	char buf[BLKSIZE];

	get_block(dev,bmap,buf);
	for(i=0; i<nblocks; i++)
	{
		if(tst_bit(buf,i) == 0)
		{
			set_bit(buf,i);
			put_block(dev,bmap,buf);
			decFreeBlocks(dev);

			printf("Allocated block = %d\n",i+1);
			return i+1;//inodes goes from 1 not 0
		}
	}

	return 0;
}

//Decrease the amount of free blocks
int decFreeBlocks(int dev)
{

	char buf[BLKSIZE];
	get_block(dev,1,buf);
	sp = (SUPER*)buf;
	sp->s_free_blocks_count--;
	put_block(dev,1,buf);

	get_block(dev,2,buf);
	gp = (GD*)buf;
	gp->bg_free_blocks_count--;
	put_block(dev,2,buf);
}


int clr_bits(char* buf,int bit)
{
	buf[bit/8] &= ~(1 << (bit%8));
}

int incFreeInodes(int dev)
{
	char buf[BLKSIZE];
	get_block(dev,1,buf);
	sp = (SUPER *)buf;
	sp->s_free_inodes_count++;
	put_block(dev,1,buf);
	get_block(dev,2,buf);
	gp = (GD *)buf;
	gp->bg_free_inodes_count++;
	put_block(dev,2,buf);
}
//Look Over
int idalloc(int dev,int ino)
{
	int i;
	char buf[BLKSIZE];
	if(ino > ninodes)
	{
		printf("inumber not in range %d\n",ino);
		return;
	}
	get_block(dev,imap,buf);
	clr_bits(buf,ino-1);
	put_block(dev,imap,buf);
	incFreeInodes(dev);
}

int incFreeBlocks(int dev)
{
	char buf[BLKSIZE];
	get_block(dev,1,buf);
	sp = (SUPER *)buf;
	sp->s_free_blocks_count++;
	put_block(dev,1,buf);

	get_block(dev,2,buf);
	gp = (GD *)buf;
	gp->bg_free_blocks_count++;
	put_block(dev,2,buf);
}
//Look Over
int bdalloc(int dev, int bno)
{
	int i;
	char buf[BLKSIZE];
	if(bno > nblocks)
	{
		printf("iblock not in range %d\n",bno);
		return;
	}
	get_block(dev,bmap,buf);
	clr_bits(buf,bno-1);
	put_block(dev,bmap,buf);
	incFreeBlocks(dev);
}