/*
 *  linux/fs/minix/bitmap.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file README.legal in the main directory of this archive
 * for more details.
 */

/*
 * Modified for 680x0 by Hamish Macdonald
 */

/* bitmap.c contains the code that handles the inode and block bitmaps */

#include <linux/sched.h>
#include <linux/minix_fs.h>
#include <linux/stat.h>
#include <linux/kernel.h>
#include <linux/string.h>

#include <asm/bitops.h>

#define clear_block(addr) (memset(addr,0,BLOCK_SIZE))

static inline int
find_first_zero (char *addr)
{
  unsigned long res;
  char *p = addr;
  __asm__ __volatile__
    ("    moveq #-1,d0\n\t"
     "1:"
     "    cmpw  %1@+,d0\n\t"
     "    bne   2f\n\t"
     "    subql #1,%0\n\t"
     "    bne   1b\n\t"
     "    bra   5f\n\t"
     "2:"
     "    movew %1@-,d0\n\t"
     "    notw  d0\n\t"
     "    movew d0,%0\n\t"
     "    negw  d0\n\t"
     "    andw  %0,d0\n\t"
     "    bfffo d0{#16,#16},%0\n\t"
     "5:"
     : "=d" (res), "=a" (p)
     : "0" (8192 >> 4), "1" (addr)
     : "d0");
  return (p - addr) * 8 + 31 - res;
}

#ifdef __mc68000__
#define BIT(bit) ((bit) ^ 15)
#else
#define BIT(bit) (bit)
#endif

static int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };

static unsigned long count_free(struct buffer_head *map[], unsigned numblocks)
{
	unsigned i, j, sum = 0;
	struct buffer_head *bh;

	for (i=0; i < numblocks; i++) {
		if (!(bh=map[i]))
			return(0);
		for (j=0; j < BLOCK_SIZE; j++)
			sum += nibblemap[bh->b_data[j] & 0xf]
				+ nibblemap[(bh->b_data[j]>>4)&0xf];
	}
	return(sum);
}

void minix_free_block(struct super_block * sb, int block)
{
	struct buffer_head * bh;
	unsigned int bit,zone;

	if (!sb) {
		printk("trying to free block on nonexistent device\n");
		return;
	}
	if ((ulong)block < sb->u.minix_sb.s_firstdatazone ||
	    (ulong)block >= sb->u.minix_sb.s_nzones) {
		printk("trying to free block not in datazone\n");
		return;
	}
	bh = get_hash_table(sb->s_dev,block,BLOCK_SIZE);
	if (bh)
		bh->b_dirt=0;
	brelse(bh);
	zone = block - sb->u.minix_sb.s_firstdatazone + 1;
	bit = zone & 8191;
	zone >>= 13;
	bh = sb->u.minix_sb.s_zmap[zone];
	if (!bh) {
		printk("minix_free_block: nonexistent bitmap buffer\n");
		return;
	}
	if (!clear_bit(BIT(bit),bh->b_data))
		printk("free_block (%04x:%d): bit already cleared\n",sb->s_dev,block);
	bh->b_dirt = 1;
	return;
}

int minix_new_block(struct super_block * sb)
{
	struct buffer_head * bh;
	int i,j;

	if (!sb) {
		printk("trying to get new block from nonexistent device\n");
		return 0;
	}
repeat:
	j = 8192;
	for (i=0 ; i<8 ; i++)
		if ((bh=sb->u.minix_sb.s_zmap[i]) != NULL)
			if ((j=find_first_zero(bh->b_data))<8192)
				break;
	if (i>=8 || !bh || j>=8192)
		return 0;
	if (set_bit(BIT(j),bh->b_data)) {
		printk("new_block: bit already set (%d)\n", j);
		goto repeat;
	}
	bh->b_dirt = 1;
	j += i*8192 + sb->u.minix_sb.s_firstdatazone-1;
	if ((ulong)j < sb->u.minix_sb.s_firstdatazone ||
	    (ulong)j >= sb->u.minix_sb.s_nzones)
		return 0;
	if (!(bh = getblk(sb->s_dev,j,BLOCK_SIZE))) {
		printk("new_block: cannot get block\n");
		return 0;
	}
	clear_block(bh->b_data);
	bh->b_uptodate = 1;
	bh->b_dirt = 1;
	brelse(bh);
	return j;
}

unsigned long minix_count_free_blocks(struct super_block *sb)
{
	return (count_free(sb->u.minix_sb.s_zmap,sb->u.minix_sb.s_zmap_blocks)
		<< sb->u.minix_sb.s_log_zone_size);
}

void minix_free_inode(struct inode * inode)
{
	struct buffer_head * bh;
	unsigned long ino;

	if (!inode)
		return;
	if (!inode->i_dev) {
		printk("free_inode: inode has no device\n");
		return;
	}
	if (inode->i_count != 1) {
		printk("free_inode: inode has count=%d\n",inode->i_count);
		return;
	}
	if (inode->i_nlink) {
		printk("free_inode: inode has nlink=%d\n",inode->i_nlink);
		return;
	}
	if (!inode->i_sb) {
		printk("free_inode: inode on nonexistent device\n");
		return;
	}
	if (inode->i_ino < 1 || inode->i_ino >= inode->i_sb->u.minix_sb.s_ninodes) {
		printk("free_inode: inode 0 or nonexistent inode\n");
		return;
	}
	ino = inode->i_ino;
	if (!(bh=inode->i_sb->u.minix_sb.s_imap[ino >> 13])) {
		printk("free_inode: nonexistent imap in superblock\n");
		return;
	}
	minix_clear_inode (inode);
	clear_inode(inode);
	if (!clear_bit(BIT(ino & 8191), bh->b_data))
		printk("free_inode: bit %lu already cleared.\n",ino);
	bh->b_dirt = 1;
}

struct inode * minix_new_inode(const struct inode * dir)
{
	struct super_block * sb;
	struct inode * inode;
	struct buffer_head * bh;
	int i,j;

	if (!dir || !(inode = get_empty_inode()))
		return NULL;
	sb = dir->i_sb;
	inode->i_sb = sb;
	inode->i_flags = inode->i_sb->s_flags;
	j = 8192;
	for (i=0 ; i<8 ; i++)
		if ((bh = inode->i_sb->u.minix_sb.s_imap[i]) != NULL)
			if ((j=find_first_zero(bh->b_data))<8192)
				break;
	if (!bh || j >= 8192) {
		iput(inode);
		return NULL;
	}
	if (set_bit(BIT(j),bh->b_data)) {    /* shouldn't happen */
		printk("new_inode: bit %u already set\n", j);
		iput(inode);
		return NULL;
	}
	bh->b_dirt = 1;
	j += i*8192;
	if (!j || (ulong)j >= inode->i_sb->u.minix_sb.s_ninodes) {
		iput(inode);
		return NULL;
	}
	inode->i_count = 1;
	inode->i_nlink = 1;
	inode->i_dev = sb->s_dev;
	inode->i_uid = current->euid;
	inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->egid;
	inode->i_dirt = 1;
	inode->i_ino = j;
	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
	inode->i_op = NULL;
	inode->i_blocks = inode->i_blksize = 0;
	insert_inode_hash(inode);
	return inode;
}

unsigned long minix_count_free_inodes(struct super_block *sb)
{
	return count_free(sb->u.minix_sb.s_imap,sb->u.minix_sb.s_imap_blocks);
}