/* * bitext.c: kernel little helper (of bit shuffling variety). * * Copyright (C) 2002 Pete Zaitcev <zaitcev@yahoo.com> * * The algorithm to search a zero bit string is geared towards its application. * We expect a couple of fixed sizes of requests, so a rotating counter, reset * by align size, should provide fast enough search while maintaining low * fragmentation. */#include <linux/smp_lock.h>#include <asm/bitext.h>#include <asm/bitops.h>/** * bit_map_string_get - find and set a bit string in bit map. * @t: the bit map. * @len: requested string length * @align: requested alignment * * Returns offset in the map or -1 if out of space. * * Not safe to call from an interrupt (uses spin_lock). */int bit_map_string_get(struct bit_map *t, int len, int align){	int offset, count;	/* siamese twins */	int off_new;	int align1;	int i;	if (align == 0)		align = 1;	align1 = align - 1;	if ((align & align1) != 0)		BUG();	if (align < 0 || align >= t->size)		BUG();	if (len <= 0 || len > t->size)		BUG();	spin_lock(&t->lock);	if (len < t->last_size)		offset = t->first_free;	else		offset = t->last_off & ~align1;	count = 0;	for (;;) {		off_new = find_next_zero_bit(t->map, t->size, offset);		off_new = (off_new + align1) & ~align1;		count += off_new - offset;		offset = off_new;		if (offset >= t->size)			offset = 0;		if (count + len > t->size) {			spin_unlock(&t->lock);/* P3 */ printk(KERN_ERR  "bitmap out: size %d used %d off %d len %d align %d count %d\n",  t->size, t->used, offset, len, align, count);			return -1;		}		if (offset + len > t->size) {			count += t->size - offset;			offset = 0;			continue;		}		i = 0;		while (test_bit(offset + i, t->map) == 0) {			i++;			if (i == len) {				for (i = 0; i < len; i++)					__set_bit(offset + i, t->map);				if (offset == t->first_free)					t->first_free = find_next_zero_bit							(t->map, t->size,							 t->first_free + len);				if ((t->last_off = offset + len) >= t->size)					t->last_off = 0;				t->used += len;				t->last_size = len;				spin_unlock(&t->lock);				return offset;			}		}		count += i + 1;		if ((offset += i + 1) >= t->size)			offset = 0;	}}void bit_map_clear(struct bit_map *t, int offset, int len){	int i;	if (t->used < len)		BUG();		/* Much too late to do any good, but alas... */	spin_lock(&t->lock);	for (i = 0; i < len; i++) {		if (test_bit(offset + i, t->map) == 0)			BUG();		__clear_bit(offset + i, t->map);	}	if (offset < t->first_free)		t->first_free = offset;	t->used -= len;	spin_unlock(&t->lock);}void bit_map_init(struct bit_map *t, unsigned long *map, int size){	if ((size & 07) != 0)		BUG();	memset(map, 0, size>>3);	memset(t, 0, sizeof *t);	spin_lock_init(&t->lock);	t->map = map;	t->size = size;	t->last_size = 0;	t->first_free = 0;}