incubator-nuttx/libs/libc/stdio/lib_ultoa_invert.c

/****************************************************************************
 * libs/libc/stdio/lib_ultoa_invert.c
 *
 * SPDX-License-Identifier: BSD-3-Clause
 * SPDX-FileCopyrightText: 2017, Keith Packard. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

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

#include "lib_ultoa_invert.h"

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

#ifdef CONFIG_LIBC_LONG_LONG
FAR char *__ultoa_invert(unsigned long long val, FAR char *str, int base)
#else
FAR char *__ultoa_invert(unsigned long val, FAR char *str, int base)
#endif
{
  int upper = 0;

  if (base & XTOA_UPPER)
    {
      upper = 1;
      base &= ~XTOA_UPPER;
    }

  do
    {
      int v;

      v   = val % base;
      val = val / base;

      if (v <= 9)
        {
          v += '0';
        }
      else
        {
          if (upper)
            v += 'A' - 10;
          else
            v += 'a' - 10;
        }

      *str++ = v;
    }
  while (val);

  return str;
}