| 1 | /*
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| 2 | Unix SMB/CIFS implementation.
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| 3 |
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| 4 | a generic binary search macro
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| 5 |
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| 6 | Copyright (C) Andrew Tridgell 2009
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| 7 |
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| 8 | This program is free software; you can redistribute it and/or modify
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| 9 | it under the terms of the GNU General Public License as published by
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| 10 | the Free Software Foundation; either version 3 of the License, or
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| 11 | (at your option) any later version.
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| 12 |
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| 13 | This program is distributed in the hope that it will be useful,
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| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | GNU General Public License for more details.
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| 17 |
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| 18 | You should have received a copy of the GNU General Public License
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| 19 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 20 | */
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| 21 |
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| 22 | #ifndef _BINSEARCH_H
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| 23 | #define _BINSEARCH_H
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| 24 |
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| 25 | /* a binary array search, where the array is an array of pointers to structures,
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| 26 | and we want to find a match for 'target' on 'field' in those structures.
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| 27 |
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| 28 | Inputs:
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| 29 | array: base pointer to an array of structures
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| 30 | arrray_size: number of elements in the array
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| 31 | field: the name of the field in the structure we are keying off
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| 32 | target: the field value we are looking for
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| 33 | comparison_fn: the comparison function
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| 34 | result: where the result of the search is put
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| 35 |
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| 36 | if the element is found, then 'result' is set to point to the found array element. If not,
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| 37 | then 'result' is set to NULL.
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| 38 |
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| 39 | The array is assumed to be sorted by the same comparison_fn as the
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| 40 | search (with, for example, qsort)
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| 41 | */
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| 42 | #define BINARY_ARRAY_SEARCH_P(array, array_size, field, target, comparison_fn, result) do { \
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| 43 | int32_t _b, _e; \
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| 44 | (result) = NULL; \
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| 45 | if (array_size) { for (_b = 0, _e = (array_size)-1; _b <= _e; ) { \
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| 46 | int32_t _i = (_b+_e)/2; \
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| 47 | int _r = comparison_fn(target, array[_i]->field); \
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| 48 | if (_r == 0) { (result) = array[_i]; break; } \
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| 49 | if (_r < 0) _e = _i - 1; else _b = _i + 1; \
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| 50 | }} } while (0)
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| 51 |
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| 52 | /*
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| 53 | like BINARY_ARRAY_SEARCH_P, but assumes that the array is an array
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| 54 | of structures, rather than pointers to structures
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| 55 |
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| 56 | result points to the found structure, or NULL
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| 57 | */
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| 58 | #define BINARY_ARRAY_SEARCH(array, array_size, field, target, comparison_fn, result) do { \
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| 59 | int32_t _b, _e; \
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| 60 | (result) = NULL; \
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| 61 | if (array_size) { for (_b = 0, _e = (array_size)-1; _b <= _e; ) { \
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| 62 | int32_t _i = (_b+_e)/2; \
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| 63 | int _r = comparison_fn(target, array[_i].field); \
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| 64 | if (_r == 0) { (result) = &array[_i]; break; } \
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| 65 | if (_r < 0) _e = _i - 1; else _b = _i + 1; \
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| 66 | }} } while (0)
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| 67 |
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| 68 | #endif
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