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| -rw-r--r-- | csrc/algorithms/arrays/minmax.h | 220 |
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diff --git a/csrc/algorithms/arrays/minmax.h b/csrc/algorithms/arrays/minmax.h new file mode 100644 index 0000000..a9fb382 --- /dev/null +++ b/csrc/algorithms/arrays/minmax.h @@ -0,0 +1,220 @@ +/** + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU Affero 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 Affero General Public License for more details. + * + * You should have received a copy of the GNU Affero General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef ALGO_ALGORITHMS_ARRAYS_MINMAX_H +#define ALGO_ALGORITHMS_ARRAYS_MINMAX_H + + +/* NB! This will not play nice if the placeholder `T` is + * not set to a type only containing [0-9A-Za-z_] (and $ + * in GNU C). Therefore, with the exception of `char`, + * `short`, `int`, `long`, `float` and `double`, you + * should only use `typedef`:ed types. */ + + +#include <stddef.h> + + +/** + * Find the minimum and maximum values in an array. + * + * `algo_make_implementation_of_get_bounds(T)` is used to make + * this function available for a particular data type `T`. And + * implementation without modifiers and attributes will be + * expanded. You may add `static`, `inline` and `__attribute__` + * before calling `algo_make_implementation_of_get_bounds(T)`. + * + * `algo_make_prototype_of_get_bounds(T)` is the prototype + * counterpart of `algo_make_implementation_of_get_bounds(T)`. + * It too is will not add any modifiers or attributes by + * default. It will neither add a semicolon at the end of + * the prototype. + * + * `algo_get_bounds(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_get_bounds(T))` gets the address of this function + * and `algo_get_bounds(T)(items, n, min, max)` calls the + * function. + * + * This function is not pure since it will edit the value + * of `min` and `max`. This function does not accept `NULL` + * arguments, if you are using GCC you should add + * `__attribute__((nonnull))` to its prototype. + * + * Undefined behaviour is invoked `n == 0`. + * + * @param items The items over to search. + * @param n The number of elements in `items`. + * @param min Output parameter for the minimum value. + * @param max Output parameter for the maximum value. + */ +//>fun () { +void algo_get_bounds__##T(const T* restrict items, size_t n, T* min, T* max) +{ + const T* end = items + n; + T maxv, minv, cur; + size_t i; + + max = min = *items++; + + while (items != end) + { + cur = *items++; + if (cur > maxv) maxv = cur; + else if (cur < minv) minv = cur; + } + + *min = min; + *max = max; +} +//>} ; . ../make_fun + + +/** + * Find the minimum and maximum values in an array. + * + * This variant of `algo_get_bounds` is suitable for + * non-numeric data. + * + * `algo_make_implementation_of_get_bounds_cmp(T)` is used to make + * this function available for a particular data type `T`. And + * implementation without modifiers and attributes will be + * expanded. You may add `static`, `inline` and `__attribute__` + * before calling `algo_make_implementation_of_get_bounds_cmp(T)`. + * + * `algo_make_prototype_of_get_bounds_cmp(T)` is the prototype + * counterpart of `algo_make_implementation_of_get_bounds_cmp(T)`. + * It too is will not add any modifiers or attributes by + * default. It will neither add a semicolon at the end of + * the prototype. + * + * `algo_get_bounds_cmp(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_get_bounds_cmp(T))` gets the address of this function + * and `algo_get_bounds_cmp(T)(items, n, cmp, min, max)` calls + * the function. + * + * This function is not pure since it will edit the value + * of `min` and `max`, and `cmp` is not necessarily pure. + * This function does not accept `NULL` arguments, if you + * are using GCC you should add `__attribute__((nonnull))` + * to its prototype. + * + * Undefined behaviour is invoked `n == 0`. + * + * @param items The items over to search. + * @param n The number of elements in `items`. + * @param cmp Function used to compare two items, it should return a. + * negative value if its first parameter is the lesser, a. + * positive value if its second parameter is the lesser. + * and zero if the parameters are equal. + * @param min Output parameter for the minimum value. + * @param max Output parameter for the maximum value. + */ +//>fun () { +void algo_get_bounds_cmp__##T(const T* restrict items, size_t n, + int (*cmp)(const T*, const T*), + T* min, T* max) +{ + const T* end = items + n; + T maxv, minv, cur; + size_t i; + + max = min = *items++; + + while (items != end) + { + cur = *items++; + if (cmp(cur, maxv) > 0) maxv = cur; + else if (cmp(cur, minv) < 0) minv = cur; + } + + *min = min; + *max = max; +} +//>} ; . ../make_fun + + +/** + * Find the minimum and maximum values in an array. + * + * This variant of `algo_get_bounds_cmp` allows you to + * store data needed for the comparison in a thread-safe + * way. It is reentrant. + * + * `algo_make_implementation_of_get_bounds_cmp_r(T)` is used to make + * this function available for a particular data type `T`. And + * implementation without modifiers and attributes will be + * expanded. You may add `static`, `inline` and `__attribute__` + * before calling `algo_make_implementation_of_get_bounds_cmp_r(T)`. + * + * `algo_make_prototype_of_get_bounds_cmp(T)` is the prototype + * counterpart of `algo_make_implementation_of_get_bounds_cmp_r(T)`. + * It too is will not add any modifiers or attributes by + * default. It will neither add a semicolon at the end of + * the prototype. + * + * `algo_get_bounds_cmp_r(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_get_bounds_cmp_r(T))` gets the address of this function + * and `algo_get_bounds_cmp_r(T)(items, n, cmp, data, min, max)` + * calls the function. + * + * This function is not pure since it will edit the value + * of `min` and `max`, and `cmp` is not necessarily pure. + * This function does not accept `NULL` arguments, if you + * are using GCC you should add `__attribute__((nonnull))` + * to its prototype. + * + * Undefined behaviour is invoked `n == 0`. + * + * @param items The items over to search. + * @param n The number of elements in `items`. + * @param cmp Function used to compare two items, it should return a + * negative value if its first parameter is the lesser, a + * positive value if its second parameter is the lesser + * and zero if the parameters are equal. `data` will be + * input as `cmp`'s third argument. + * @param data Arbitrary data (may be `NULL`) to pass throught to `cmp`. + * @param min Output parameter for the minimum value. + * @param max Output parameter for the maximum value. + */ +//>fun () { +void algo_get_bounds_cmp_r__##T(const T* restrict items, size_t n, + int (*cmp)(const T*, const T*, void*), + void* data, T* min, T* max) +{ + const T* end = items + n; + T maxv, minv, cur; + size_t i; + + max = min = *items++; + + while (items != end) + { + cur = *items++; + if (cmp(cur, maxv, data) > 0) maxv = cur; + else if (cmp(cur, minv, data) < 0) minv = cur; + } + + *min = min; + *max = max; +} +//>} ; . ../make_fun + + +#endif + |