diff options
Diffstat (limited to 'lib/ldb/ldb_sqlite3/base160.c')
-rw-r--r-- | lib/ldb/ldb_sqlite3/base160.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/lib/ldb/ldb_sqlite3/base160.c b/lib/ldb/ldb_sqlite3/base160.c new file mode 100644 index 0000000..7ad39f7 --- /dev/null +++ b/lib/ldb/ldb_sqlite3/base160.c @@ -0,0 +1,154 @@ +/* + 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; +} |