/* bit search implementation

   *
   * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *

   * Copyright (C) 2008 IBM Corporation
   * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
   * (Inspired by David Howell's find_next_bit implementation)
   *

   * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
   * size and improve performance, 2015.
   *

   * 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/bitmap.h>

  #include <linux/export.h>

  #include <linux/kernel.h>

  #if !defined(find_next_bit) || !defined(find_next_zero_bit)

  /*

   * This is a common helper function for find_next_bit and
   * find_next_zero_bit.  The difference is the "invert" argument, which
   * is XORed with each fetched word before searching it for one bits.

   */

  static unsigned long _find_next_bit(const unsigned long *addr,
  		unsigned long nbits, unsigned long start, unsigned long invert)

  {

  	unsigned long tmp;

  	if (unlikely(start >= nbits))

  		return nbits;
  
  	tmp = addr[start / BITS_PER_LONG] ^ invert;
  
  	/* Handle 1st word. */
  	tmp &= BITMAP_FIRST_WORD_MASK(start);
  	start = round_down(start, BITS_PER_LONG);
  
  	while (!tmp) {
  		start += BITS_PER_LONG;
  		if (start >= nbits)
  			return nbits;
  
  		tmp = addr[start / BITS_PER_LONG] ^ invert;

  	}

  	return min(start + __ffs(tmp), nbits);

  }

  #endif

  #ifndef find_next_bit

  /*

   * Find the next set bit in a memory region.

   */

  unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
  			    unsigned long offset)
  {
  	return _find_next_bit(addr, size, offset, 0UL);
  }
  EXPORT_SYMBOL(find_next_bit);
  #endif
  
  #ifndef find_next_zero_bit

  unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
  				 unsigned long offset)

  {

  	return _find_next_bit(addr, size, offset, ~0UL);

  }

  EXPORT_SYMBOL(find_next_zero_bit);

  #endif

  #ifndef find_first_bit

  /*
   * Find the first set bit in a memory region.
   */

  unsigned long find_first_bit(const unsigned long *addr, unsigned long size)

  {

  	unsigned long idx;

  	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
  		if (addr[idx])
  			return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);

  	}

  	return size;

  }

  EXPORT_SYMBOL(find_first_bit);

  #endif

  #ifndef find_first_zero_bit

  /*
   * Find the first cleared bit in a memory region.
   */

  unsigned long find_first_zero_bit(const unsigned long *addr, unsigned long size)

  {

  	unsigned long idx;

  	for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
  		if (addr[idx] != ~0UL)
  			return min(idx * BITS_PER_LONG + ffz(addr[idx]), size);

  	}

  	return size;

  }

  EXPORT_SYMBOL(find_first_zero_bit);

  #endif

  #ifndef find_last_bit
  unsigned long find_last_bit(const unsigned long *addr, unsigned long size)
  {
  	if (size) {
  		unsigned long val = BITMAP_LAST_WORD_MASK(size);
  		unsigned long idx = (size-1) / BITS_PER_LONG;
  
  		do {
  			val &= addr[idx];
  			if (val)
  				return idx * BITS_PER_LONG + __fls(val);
  
  			val = ~0ul;
  		} while (idx--);
  	}
  	return size;
  }
  EXPORT_SYMBOL(find_last_bit);
  #endif

  #ifdef __BIG_ENDIAN
  
  /* include/linux/byteorder does not 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
  }

  #if !defined(find_next_bit_le) || !defined(find_next_zero_bit_le)
  static unsigned long _find_next_bit_le(const unsigned long *addr,
  		unsigned long nbits, unsigned long start, unsigned long invert)

  {

  	unsigned long tmp;

  	if (unlikely(start >= nbits))

  		return nbits;
  
  	tmp = addr[start / BITS_PER_LONG] ^ invert;
  
  	/* Handle 1st word. */
  	tmp &= ext2_swab(BITMAP_FIRST_WORD_MASK(start));
  	start = round_down(start, BITS_PER_LONG);

  	while (!tmp) {
  		start += BITS_PER_LONG;
  		if (start >= nbits)
  			return nbits;
  
  		tmp = addr[start / BITS_PER_LONG] ^ invert;

  	}

  	return min(start + __ffs(ext2_swab(tmp)), nbits);
  }
  #endif
  
  #ifndef find_next_zero_bit_le
  unsigned long find_next_zero_bit_le(const void *addr, unsigned
  		long size, unsigned long offset)
  {
  	return _find_next_bit_le(addr, size, offset, ~0UL);

  }

  EXPORT_SYMBOL(find_next_zero_bit_le);

  #endif

  #ifndef find_next_bit_le

  unsigned long find_next_bit_le(const void *addr, unsigned

  		long size, unsigned long offset)
  {

  	return _find_next_bit_le(addr, size, offset, 0UL);

  }

  EXPORT_SYMBOL(find_next_bit_le);

  #endif

  #endif /* __BIG_ENDIAN */