2 base160 code used by ldb_sqlite3
4 Copyright (C) 2004 Derrell Lipman
6 This library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 3 of the License, or (at your option) any later version.
11 This library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with this library; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * ldb_sqlite3_base160()
25 * Convert an integer value to a string containing the base 160 representation
26 * of the integer. We always convert to a string representation that is 4
27 * bytes in length, and we always null terminate.
31 * The value to be converted
34 * Buffer in which the result is to be placed
39 static unsigned char base160tab
[161] =
41 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , /* 0-9 */
42 58 , 59 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , /* : ; A-H */
43 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , /* I-R */
44 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 97 , 98 , /* S-Z , a-b */
45 99 , 100, 101, 102, 103, 104, 105, 106, 107, 108, /* c-l */
46 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, /* m-v */
47 119, 120, 121, 122, 160, 161, 162, 163, 164, 165, /* w-z, latin1 */
48 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, /* latin1 */
49 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, /* latin1 */
50 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, /* latin1 */
51 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, /* latin1 */
52 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, /* latin1 */
53 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, /* latin1 */
54 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, /* latin1 */
55 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, /* latin1 */
56 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, /* latin1 */
64 * Convert an unsigned long integer into a base160 representation of the
69 * value to be converted
72 * character array, 5 bytes long, into which the base160 representation
73 * will be placed. The result will be a four-digit representation of the
74 * number (with leading zeros prepended as necessary), and null
81 lsqlite3_base160(unsigned long val
,
82 unsigned char result
[5])
86 for (i
= 3; i
>= 0; i
--) {
88 result
[i
] = base160tab
[val
% 160];
97 * lsqlite3_base160Next()
99 * Retrieve the next-greater number in the base160 sequence for the terminal
100 * tree node (the last four digits). Only one tree level (four digits) are
104 * base160 -- a character array containing either an empty string (in which
105 * case no operation is performed), or a string of base160 digits
106 * with a length of a multiple of four digits.
108 * Upon return, the trailing four digits (one tree level) will
109 * have been incremented by 1.
112 * base160 -- the modified array
115 lsqlite3_base160Next(char base160
[])
119 unsigned char * pTab
;
120 char * pBase160
= base160
;
123 * We need a minimum of four digits, and we will always get a multiple of
126 if (len
= strlen(pBase160
)) >= 4)
128 pBase160
+= strlen(pBase160
) - 1;
130 /* We only carry through four digits: one level in the tree */
131 for (i
= 0; i
< 4; i
++) {
133 /* What base160 value does this digit have? */
134 pTab
= strchr(base160tab
, *pBase160
);
136 /* Is there a carry? */
137 if (pTab
< base160tab
+ sizeof(base160tab
) - 1) {
139 /* Nope. Just increment this value and we're done. */
145 * There's a carry. This value gets base160tab[0], we
146 * decrement the buffer pointer to get the next higher-order
147 * digit, and continue in the loop.
149 *pBase160
-- = base160tab
[0];