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/*
base160 code used by ldb_sqlite3
Copyright (C) 2004 Derrell Lipman
This 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 3 of the License, or (at your option) any later version.
This 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 this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* ldb_sqlite3_base160()
*
* Convert an integer value to a string containing the base 160 representation
* of the integer. We always convert to a string representation that is 4
* bytes in length, and we always null terminate.
*
* Parameters:
* val --
* The value to be converted
*
* result --
* Buffer in which the result is to be placed
*
* Returns:
* nothing
*/
static unsigned char base160tab[161] =
{
48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , /* 0-9 */
58 , 59 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , /* : ; A-H */
73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , /* I-R */
83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 97 , 98 , /* S-Z , a-b */
99 , 100, 101, 102, 103, 104, 105, 106, 107, 108, /* c-l */
109, 110, 111, 112, 113, 114, 115, 116, 117, 118, /* m-v */
119, 120, 121, 122, 160, 161, 162, 163, 164, 165, /* w-z, latin1 */
166, 167, 168, 169, 170, 171, 172, 173, 174, 175, /* latin1 */
176, 177, 178, 179, 180, 181, 182, 183, 184, 185, /* latin1 */
186, 187, 188, 189, 190, 191, 192, 193, 194, 195, /* latin1 */
196, 197, 198, 199, 200, 201, 202, 203, 204, 205, /* latin1 */
206, 207, 208, 209, 210, 211, 212, 213, 214, 215, /* latin1 */
216, 217, 218, 219, 220, 221, 222, 223, 224, 225, /* latin1 */
226, 227, 228, 229, 230, 231, 232, 233, 234, 235, /* latin1 */
236, 237, 238, 239, 240, 241, 242, 243, 244, 245, /* latin1 */
246, 247, 248, 249, 250, 251, 252, 253, 254, 255, /* latin1 */
'\0'
};
/*
* lsqlite3_base160()
*
* Convert an unsigned long integer into a base160 representation of the
* number.
*
* Parameters:
* val --
* value to be converted
*
* result --
* character array, 5 bytes long, into which the base160 representation
* will be placed. The result will be a four-digit representation of the
* number (with leading zeros prepended as necessary), and null
* terminated.
*
* Returns:
* Nothing
*/
void
lsqlite3_base160(unsigned long val,
unsigned char result[5])
{
int i;
for (i = 3; i >= 0; i--) {
result[i] = base160tab[val % 160];
val /= 160;
}
result[4] = '\0';
}
/*
* lsqlite3_base160Next()
*
* Retrieve the next-greater number in the base160 sequence for the terminal
* tree node (the last four digits). Only one tree level (four digits) are
* operated on.
*
* Parameters:
* base160 -- a character array containing either an empty string (in which
* case no operation is performed), or a string of base160 digits
* with a length of a multiple of four digits.
*
* Upon return, the trailing four digits (one tree level) will
* have been incremented by 1.
*
* Returns:
* base160 -- the modified array
*/
char *
lsqlite3_base160Next(char base160[])
{
int i;
int len;
unsigned char * pTab;
char * pBase160 = base160;
/*
* We need a minimum of four digits, and we will always get a multiple of
* four digits.
*/
if ((len = strlen(pBase160)) >= 4)
{
pBase160 += strlen(pBase160) - 1;
/* We only carry through four digits: one level in the tree */
for (i = 0; i < 4; i++) {
/* What base160 value does this digit have? */
pTab = strchr(base160tab, *pBase160);
/* Is there a carry? */
if (pTab < base160tab + sizeof(base160tab) - 1) {
/* Nope. Just increment this value and we're done. */
*pBase160 = *++pTab;
break;
} else {
/*
* There's a carry. This value gets base160tab[0], we
* decrement the buffer pointer to get the next higher-order
* digit, and continue in the loop.
*/
*pBase160-- = base160tab[0];
}
}
}
return base160;
}
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