/****************************************************************************
 * libs/libc/string/lib_bsdstrncmp.c
 *
 * SPDX-License-Identifier: BSD
 * SPDX-FileCopyrightText: 1994-2009  Red Hat, Inc. All rights reserved
 *
 * Copyright (c) 1994-2009  Red Hat, Inc. All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the BSD License.   This program is distributed in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
 * including the implied warranties of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  A copy of this license is available at
 * http://www.opensource.org/licenses. Any Red Hat trademarks that are
 * incorporated in the source code or documentation are not subject to
 * the BSD License and may only be used or replicated with the express
 * permission of Red Hat, Inc.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#include <sys/types.h>
#include <string.h>

#include "libc.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Public Functions
 ****************************************************************************/

#if !defined(CONFIG_LIBC_ARCH_STRNCMP) && defined(LIBC_BUILD_STRNCMP)
#undef strncmp
no_builtin("strncmp")
nosanitize_address
int strncmp(FAR const char *cs, FAR const char *ct, size_t nb)
{
  if (nb == 0)
    {
      return 0;
    }

  /* If cs or ct are unaligned, then compare bytes. */

  if (!UNALIGNED(cs, ct))
    {
      FAR libc_data_t *a1 = (FAR libc_data_t *)cs;
      FAR libc_data_t *a2 = (FAR libc_data_t *)ct;

      while (nb >= LITTLEBLOCKSIZE && *a1 == *a2)
        {
          nb -= LITTLEBLOCKSIZE;

          if (nb == 0 || DETECTNULL(*a1))
            {
              return 0;
            }

          a1++;
          a2++;
        }

      cs = (FAR char *)a1;
      ct = (FAR char *)a2;
    }
  else if (!UNALIGNED4(cs, ct))
    {
      FAR uint32_t *a1 = (FAR uint32_t *)cs;
      FAR uint32_t *a2 = (FAR uint32_t *)ct;

      while (nb >= LITTLEBLOCKSIZE4 && *a1 == *a2)
        {
          nb -= LITTLEBLOCKSIZE4;

          if (nb == 0 || DETECTNULL32(*a1))
            {
              return 0;
            }

          a1++;
          a2++;
        }

      cs = (FAR char *)a1;
      ct = (FAR char *)a2;
    }

  while (nb-- > 0 && *cs == *ct)
    {
      if (nb == 0 || *cs == '\0')
        {
          return 0;
        }

      cs++;
      ct++;
    }

  return *cs - *ct;
}
#endif