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| -rw-r--r-- | lib/util/binsearch.h | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/lib/util/binsearch.h b/lib/util/binsearch.h new file mode 100644 index 0000000000..ac83990072 --- /dev/null +++ b/lib/util/binsearch.h @@ -0,0 +1,68 @@ +/* + Unix SMB/CIFS implementation. + + a generic binary search macro + + Copyright (C) Andrew Tridgell 2009 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +#ifndef _BINSEARCH_H +#define _BINSEARCH_H + +/* a binary array search, where the array is an array of pointers to structures, + and we want to find a match for 'target' on 'field' in those structures. + + Inputs: + array: base pointer to an array of structures + arrray_size: number of elements in the array + field: the name of the field in the structure we are keying off + target: the field value we are looking for + comparison_fn: the comparison function + result: where the result of the search is put + + if the element is found, then 'result' is set to point to the found array element. If not, + then 'result' is set to NULL. + + The array is assumed to be sorted by the same comparison_fn as the + search (with, for example, qsort) + */ +#define BINARY_ARRAY_SEARCH_P(array, array_size, field, target, comparison_fn, result) do { \ + int32_t _b, _e; \ + (result) = NULL; \ + if (array_size) { for (_b = 0, _e = (array_size)-1; _b <= _e; ) { \ + int32_t _i = (_b+_e)/2; \ + int _r = comparison_fn(target, array[_i]->field); \ + if (_r == 0) { (result) = array[_i]; break; } \ + if (_r < 0) _e = _i - 1; else _b = _i + 1; \ + }} } while (0) + +/* + like BINARY_ARRAY_SEARCH_P, but assumes that the array is an array + of structures, rather than pointers to structures + + result points to the found structure, or NULL + */ +#define BINARY_ARRAY_SEARCH(array, array_size, field, target, comparison_fn, result) do { \ + int32_t _b, _e; \ + (result) = NULL; \ + if (array_size) { for (_b = 0, _e = (array_size)-1; _b <= _e; ) { \ + int32_t _i = (_b+_e)/2; \ + int _r = comparison_fn(target, array[_i].field); \ + if (_r == 0) { (result) = &array[_i]; break; } \ + if (_r < 0) _e = _i - 1; else _b = _i + 1; \ + }} } while (0) + +#endif |