glibc/stdlib/l64a.c

/* Copyright (C) 1995-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <stdlib.h>

/* Conversion table.  */
static const char conv_table[64] =
{
  '.', '/', '0', '1', '2', '3', '4', '5',
  '6', '7', '8', '9', 'A', 'B', 'C', 'D',
  'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
  'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
  'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b',
  'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
  'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
  's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
};

char *
l64a (long int n)
{
  unsigned long int m = (unsigned long int) n;
  static char result[7];
  int cnt;

  /* The standard says that only 32 bits are used.  */
  m &= 0xffffffff;

  if (m == 0ul)
    /* The value for N == 0 is defined to be the empty string. */
    return (char *) "";

  for (cnt = 0; m > 0ul; ++cnt)
    {
      result[cnt] = conv_table[m & 0x3f];
      m >>= 6;
    }
  result[cnt] = '\0';

  return result;
}