/* find_next_bit.c: fallback find next bit implementation
   *
   * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/bitops.h>

  #include <linux/module.h>

  #include <asm/types.h>

  #include <asm/byteorder.h>

  #define BITOP_WORD(nr)		((nr) / BITS_PER_LONG)
  
  /**
   * find_next_bit - find the next set bit in a memory region
   * @addr: The address to base the search on
   * @offset: The bitnumber to start searching at
   * @size: The maximum size to search
   */
  unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
  		unsigned long offset)

  {

  	const unsigned long *p = addr + BITOP_WORD(offset);
  	unsigned long result = offset & ~(BITS_PER_LONG-1);

  	unsigned long tmp;

  	if (offset >= size)
  		return size;
  	size -= result;
  	offset %= BITS_PER_LONG;

  	if (offset) {

  		tmp = *(p++);
  		tmp &= (~0UL << offset);
  		if (size < BITS_PER_LONG)
  			goto found_first;
  		if (tmp)
  			goto found_middle;
  		size -= BITS_PER_LONG;
  		result += BITS_PER_LONG;
  	}
  	while (size & ~(BITS_PER_LONG-1)) {
  		if ((tmp = *(p++)))
  			goto found_middle;
  		result += BITS_PER_LONG;
  		size -= BITS_PER_LONG;

  	}

  	if (!size)
  		return result;
  	tmp = *p;

  found_first:
  	tmp &= (~0UL >> (BITS_PER_LONG - size));
  	if (tmp == 0UL)		/* Are any bits set? */
  		return result + size;	/* Nope. */
  found_middle:
  	return result + __ffs(tmp);
  }

  EXPORT_SYMBOL(find_next_bit);

  /*
   * This implementation of find_{first,next}_zero_bit was stolen from
   * Linus' asm-alpha/bitops.h.
   */
  unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
  		unsigned long offset)
  {
  	const unsigned long *p = addr + BITOP_WORD(offset);
  	unsigned long result = offset & ~(BITS_PER_LONG-1);
  	unsigned long tmp;

  	if (offset >= size)
  		return size;
  	size -= result;
  	offset %= BITS_PER_LONG;
  	if (offset) {
  		tmp = *(p++);
  		tmp |= ~0UL >> (BITS_PER_LONG - offset);
  		if (size < BITS_PER_LONG)
  			goto found_first;
  		if (~tmp)
  			goto found_middle;
  		size -= BITS_PER_LONG;
  		result += BITS_PER_LONG;
  	}
  	while (size & ~(BITS_PER_LONG-1)) {
  		if (~(tmp = *(p++)))
  			goto found_middle;
  		result += BITS_PER_LONG;
  		size -= BITS_PER_LONG;

  	}

  	if (!size)
  		return result;
  	tmp = *p;

  found_first:
  	tmp |= ~0UL << size;
  	if (tmp == ~0UL)	/* Are any bits zero? */
  		return result + size;	/* Nope. */
  found_middle:
  	return result + ffz(tmp);

  }

  EXPORT_SYMBOL(find_next_zero_bit);

  
  #ifdef __BIG_ENDIAN
  
  /* include/linux/byteorder does not support "unsigned long" type */
  static inline unsigned long ext2_swabp(const unsigned long * x)
  {
  #if BITS_PER_LONG == 64
  	return (unsigned long) __swab64p((u64 *) x);
  #elif BITS_PER_LONG == 32
  	return (unsigned long) __swab32p((u32 *) x);
  #else
  #error BITS_PER_LONG not defined
  #endif
  }
  
  /* include/linux/byteorder doesn't support "unsigned long" type */
  static inline unsigned long ext2_swab(const unsigned long y)
  {
  #if BITS_PER_LONG == 64
  	return (unsigned long) __swab64((u64) y);
  #elif BITS_PER_LONG == 32
  	return (unsigned long) __swab32((u32) y);
  #else
  #error BITS_PER_LONG not defined
  #endif
  }
  
  unsigned long generic_find_next_zero_le_bit(const unsigned long *addr, unsigned
  		long size, unsigned long offset)
  {
  	const unsigned long *p = addr + BITOP_WORD(offset);
  	unsigned long result = offset & ~(BITS_PER_LONG - 1);
  	unsigned long tmp;
  
  	if (offset >= size)
  		return size;
  	size -= result;
  	offset &= (BITS_PER_LONG - 1UL);
  	if (offset) {
  		tmp = ext2_swabp(p++);
  		tmp |= (~0UL >> (BITS_PER_LONG - offset));
  		if (size < BITS_PER_LONG)
  			goto found_first;
  		if (~tmp)
  			goto found_middle;
  		size -= BITS_PER_LONG;
  		result += BITS_PER_LONG;
  	}
  
  	while (size & ~(BITS_PER_LONG - 1)) {
  		if (~(tmp = *(p++)))
  			goto found_middle_swap;
  		result += BITS_PER_LONG;
  		size -= BITS_PER_LONG;
  	}
  	if (!size)
  		return result;
  	tmp = ext2_swabp(p);
  found_first:
  	tmp |= ~0UL << size;
  	if (tmp == ~0UL)	/* Are any bits zero? */
  		return result + size; /* Nope. Skip ffz */
  found_middle:
  	return result + ffz(tmp);
  
  found_middle_swap:
  	return result + ffz(ext2_swab(tmp));
  }
  
  EXPORT_SYMBOL(generic_find_next_zero_le_bit);

  unsigned long generic_find_next_le_bit(const unsigned long *addr, unsigned
  		long size, unsigned long offset)
  {
  	const unsigned long *p = addr + BITOP_WORD(offset);
  	unsigned long result = offset & ~(BITS_PER_LONG - 1);
  	unsigned long tmp;
  
  	if (offset >= size)
  		return size;
  	size -= result;
  	offset &= (BITS_PER_LONG - 1UL);
  	if (offset) {
  		tmp = ext2_swabp(p++);
  		tmp &= (~0UL << offset);
  		if (size < BITS_PER_LONG)
  			goto found_first;
  		if (tmp)
  			goto found_middle;
  		size -= BITS_PER_LONG;
  		result += BITS_PER_LONG;
  	}
  
  	while (size & ~(BITS_PER_LONG - 1)) {
  		tmp = *(p++);
  		if (tmp)
  			goto found_middle_swap;
  		result += BITS_PER_LONG;
  		size -= BITS_PER_LONG;
  	}
  	if (!size)
  		return result;
  	tmp = ext2_swabp(p);
  found_first:
  	tmp &= (~0UL >> (BITS_PER_LONG - size));
  	if (tmp == 0UL)		/* Are any bits set? */
  		return result + size; /* Nope. */
  found_middle:
  	return result + __ffs(tmp);
  
  found_middle_swap:
  	return result + __ffs(ext2_swab(tmp));
  }
  EXPORT_SYMBOL(generic_find_next_le_bit);

  #endif /* __BIG_ENDIAN */