// SPDX-License-Identifier: GPL-2.0-or-later

  /* 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.

   */
  
  #include <linux/bitops.h>

  #include <linux/bitmap.h>

  #include <linux/export.h>

  #include <linux/kernel.h>

  #include <linux/minmax.h>

  #if !defined(find_next_bit) || !defined(find_next_zero_bit) ||			\
  	!defined(find_next_bit_le) || !defined(find_next_zero_bit_le) ||	\
  	!defined(find_next_and_bit)

  /*

   * This is a common helper function for find_next_bit, find_next_zero_bit, and
   * find_next_and_bit. The differences are:
   *  - The "invert" argument, which is XORed with each fetched word before
   *    searching it for one bits.
   *  - The optional "addr2", which is anded with "addr1" if present.

   */

  static unsigned long _find_next_bit(const unsigned long *addr1,

  		const unsigned long *addr2, unsigned long nbits,

  		unsigned long start, unsigned long invert, unsigned long le)

  {

  	unsigned long tmp, mask;

  	if (unlikely(start >= nbits))

  		return nbits;

  	tmp = addr1[start / BITS_PER_LONG];
  	if (addr2)
  		tmp &= addr2[start / BITS_PER_LONG];
  	tmp ^= invert;

  
  	/* Handle 1st word. */

  	mask = BITMAP_FIRST_WORD_MASK(start);
  	if (le)
  		mask = swab(mask);
  
  	tmp &= mask;

  	start = round_down(start, BITS_PER_LONG);
  
  	while (!tmp) {
  		start += BITS_PER_LONG;
  		if (start >= nbits)
  			return nbits;

  		tmp = addr1[start / BITS_PER_LONG];
  		if (addr2)
  			tmp &= addr2[start / BITS_PER_LONG];
  		tmp ^= invert;

  	}

  	if (le)
  		tmp = swab(tmp);

  	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, NULL, size, offset, 0UL, 0);

  }
  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, NULL, size, offset, ~0UL, 0);

  }

  EXPORT_SYMBOL(find_next_zero_bit);

  #endif

  #if !defined(find_next_and_bit)
  unsigned long find_next_and_bit(const unsigned long *addr1,
  		const unsigned long *addr2, unsigned long size,
  		unsigned long offset)
  {

  	return _find_next_bit(addr1, addr2, size, offset, 0UL, 0);

  }
  EXPORT_SYMBOL(find_next_and_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

  #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(addr, NULL, size, offset, ~0UL, 1);

  }

  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(addr, NULL, size, offset, 0UL, 1);

  }

  EXPORT_SYMBOL(find_next_bit_le);

  #endif

  #endif /* __BIG_ENDIAN */

  
  unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
  			       unsigned long size, unsigned long offset)
  {
  	offset = find_next_bit(addr, size, offset);
  	if (offset == size)
  		return size;
  
  	offset = round_down(offset, 8);
  	*clump = bitmap_get_value8(addr, offset);
  
  	return offset;
  }
  EXPORT_SYMBOL(find_next_clump8);