1 /* Copyright (c) 2002 Jeff Johnston <jjohnstn@redhat.com> */
2 /* l64a - convert long to radix-64 ascii string
3 *
4 * Conversion is performed on at most 32-bits of input value starting
5 * from least significant bits to the most significant bits.
6 *
7 * The routine splits the input value into groups of 6 bits for up to
8 * 32 bits of input. This means that the last group may be 2 bits
9 * (bits 30 and 31).
10 *
11 * Each group of 6 bits forms a value from 0-63 which is converted into
12 * a character as follows:
13 * 0 = '.'
14 * 1 = '/'
15 * 2-11 = '0' to '9'
16 * 12-37 = 'A' to 'Z'
17 * 38-63 = 'a' to 'z'
18 *
19 * When the remaining bits are zero or all 32 bits have been translated,
20 * a nul terminator is appended to the resulting string. An input value of
21 * 0 results in an empty string.
22 */
23
24 #include <_ansi.h>
25 #include <stdlib.h>
26
27 static const char R64_ARRAY[] = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
28
29 char *
l64a(long value)30 l64a (long value)
31 {
32 char *ptr;
33 char *result;
34 int i, index;
35 unsigned long tmp = (unsigned long)value & 0xffffffff;
36 static NEWLIB_THREAD_LOCAL char _l64a_buf[8];
37
38 result = _l64a_buf;
39 ptr = result;
40
41 for (i = 0; i < 6; ++i)
42 {
43 if (tmp == 0)
44 {
45 *ptr = '\0';
46 break;
47 }
48
49 index = tmp & (64 - 1);
50 *ptr++ = R64_ARRAY[index];
51 tmp >>= 6;
52 }
53
54 return result;
55 }
56
