stdlib/l64a.c

   1 /* Copyright (C) 1995-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <stdlib.h>
  19
  20 /* Conversion table.  */
  21 static const char conv_table[64] =
  22 {
  23   '.', '/', '0', '1', '2', '3', '4', '5',
  24   '6', '7', '8', '9', 'A', 'B', 'C', 'D',
  25   'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
  26   'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
  27   'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b',
  28   'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
  29   'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
  30   's', 't', 'u', 'v', 'w', 'x', 'y', 'z'
  31 };
  32
  33 char *
  34 l64a (long int n)
  35 {
  36   unsigned long int m = (unsigned long int) n;
  37   static char result[7];
  38   int cnt;
  39
  40   /* The standard says that only 32 bits are used.  */
  41   m &= 0xffffffff;
  42
  43   if (m == 0ul)
  44     /* The value for N == 0 is defined to be the empty string. */
  45     return (char *) "";
  46
  47   for (cnt = 0; m > 0ul; ++cnt)
  48     {
  49       result[cnt] = conv_table[m & 0x3f];
  50       m >>= 6;
  51     }
  52   result[cnt] = '\0';
  53
  54   return result;
  55 }