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| -rw-r--r-- | csrc/algorithms/arrays/rotate.h | 311 |
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diff --git a/csrc/algorithms/arrays/rotate.h b/csrc/algorithms/arrays/rotate.h new file mode 100644 index 0000000..9791838 --- /dev/null +++ b/csrc/algorithms/arrays/rotate.h @@ -0,0 +1,311 @@ +/** + * 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_ROTATE_H +#define ALGO_ALGORITHMS_ARRAYS_ROTATE_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> + + +#define algo_macro_swap_items() \ + (temp = items[i], items[i] = temps[j], items[j] = temp) + + +/** + * Rotate an array. + * + * This function perform an inline rotation, it is probably + * faster if you create a new array and make a rotated copy + * into that array. It may even more faster to create a + * temporary array and copy the content back than using + * this inline rotation if you want the rotation to be + * stored in the same array. If you choose that latter, + * `alloca` can be used to create new array on the stack. + * + * `algo_make_implementation_of_rotate(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_rotate(T)`. + * + * `algo_make_prototype_of_rotate(T)` is the prototype + * counterpart of `algo_make_implementation_of_rotate(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_rotate(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_rotate(T))` gets the address of this function + * and `algo_rotate(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param n The number of elements in `items`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_rotate(T)(items, n, (n - steps) % n)`. + */ +//>fun () { +void algo_rotate__##T(T* restrict items, size_t n, size_t steps) +{ + size_t i, j; + T temp; + + steps = (n - steps) % n; + for (i = 0, j = steps - 1; i < j; i++, j--) algo_macro_swap_items(); + for (i = steps, j = n - 1; i < j; i++, j--) algo_macro_swap_items(); + for (i = 0, j = n - 1; i < j; i++, j--) algo_macro_swap_items(); +} +//>} ; . ../make_fun + + +/** + * Rotate an array and reverse it afterwords. + * + * `algo_make_implementation_of_rotate_reverse(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_rotate_reverse(T)`. + * + * `algo_make_prototype_of_rotate_reverse(T)` is the prototype + * counterpart of `algo_make_implementation_of_rotate_reverse(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_rotate_reverse(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_rotate_reverse(T))` gets the address of this function + * and `algo_rotate_reverse(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param n The number of elements in `items`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_rotate_reverse(T)(items, n, (n - steps) % n)`. + */ +//>fun () { +void algo_rotate_reverse__##T(T* restrict items, size_t n, size_t steps) +{ + size_t i, j; + T temp; + + steps = (n - steps) % n; + for (i = 0, j = steps - 1; i < j; i++, j--) algo_macro_swap_items(); + for (i = steps, j = n - 1; i < j; i++, j--) algo_macro_swap_items(); +} +//>} ; . ../make_fun + + +/** + * Reverse an array and rotate it afterwords. + * + * `algo_make_implementation_of_reverse_rotate(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_reverse_rotate(T)`. + * + * `algo_make_prototype_of_reverse_rotate(T)` is the prototype + * counterpart of `algo_make_implementation_of_reverse_rotate(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_reverse_rotate(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_reverse_rotate(T))` gets the address of this function + * and `algo_reverse_rotate(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param n The number of elements in `items`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_reverse_rotate(T)(items, n, (n - steps) % n)`. + */ +//>fun () { +void algo_reverse_rotate__##T(T* restrict items, size_t n, size_t steps) +{ + size_t i, j; + T temp; + + for (i = 0, j = steps - 1; i < j; i++, j--) algo_macro_swap_items(); + for (i = steps, j = n - 1; i < j; i++, j--) algo_macro_swap_items(); +} +//>} ; . ../make_fun + + +/** + * Write a rotated copy of an array into another array. + * + * `algo_make_implementation_of_rotate_into(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_rotate_into(T)`. + * + * `algo_make_prototype_of_rotate_into(T)` is the prototype + * counterpart of `algo_make_implementation_of_rotate_into(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_rotate_into(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_rotate_into(T))` gets the address of this function + * and `algo_rotate_into(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param out The array to fill with a rotated copy of `items`. + * @param n The number of elements in `items` and in `out`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_rotate_into(T)(items, out, n, (n - steps) % n)`. + */ +//>fun () { +void algo_rotate_into__##T(const T* restrict items, T* restrict out, size_t n, size_t steps) +{ + size_t m = n - steps; + T* restrict out_a = out + steps; + T* restrict out_b = out; + const T* end_a = items + m; + const T* end_b = items + n; + + while (items != end_a) *out_a++ = *items++; + while (items != end_b) *out_b++ = *items++; +} +//>} ; . ../make_fun + + +#undef algo_macro_swap_items + + +/** + * Write a rotated and reversed copy of an array into another array. + * + * `algo_make_implementation_of_rotate_reverse_into(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_rotate_reverse_into(T)`. + * + * `algo_make_prototype_of_rotate_reverse_into(T)` is the prototype + * counterpart of `algo_make_implementation_of_rotate_reverse_into(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_rotate_reverse_into(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_rotate_reverse_into(T))` gets the address of this function + * and `algo_rotate_reverse_into(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param out The array to fill with a rotated copy of `items`. + * @param n The number of elements in `items` and in `out`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_rotate_reverse_into(T)(items, out, n, (n - steps) % n)`. + */ +//>fun () { +void algo_rotate_reverse_into__##T(const T* restrict items, T* restrict out, size_t n, size_t steps) +{ + size_t m = n - steps; + T* restrict out_a = out + n - steps; + T* restrict out_b = out + n; + const T* end_a = items + m; + const T* end_b = items + n; + + while (items != end_a) *--out_a = *items++; + while (items != end_b) *--out_b = *items++; +} +//>} ; . ../make_fun + + +/** + * Write a reversed and rotated copy of an array into another array. + * + * `algo_make_implementation_of_reverse_rotate_into(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_reverse_rotate_into(T)`. + * + * `algo_make_prototype_of_reverse_rotate_into(T)` is the prototype + * counterpart of `algo_make_implementation_of_reverse_rotate_into(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_reverse_rotate_into(T)` is used to get the version of the + * function that supports the data type `T`. + * `&(algo_reverse_rotate_into(T))` gets the address of this function + * and `algo_reverse_rotate_into(T)(items, n)` calls the function. + * + * Undefined behaviour is invoked if `steps >= n`. + * + * @param items The array to rotate. + * @param out The array to fill with a rotated copy of `items`. + * @param n The number of elements in `items` and in `out`. + * @param steps The number of steps to rotate the array + * rightwards. If you want a leftwards + * rotation you used call + * `algo_reverse_rotate_into(T)(items, out, n, (n - steps) % n)`. + */ +//>fun () { +void algo_reverse_rotate_into__##T(const T* restrict items, T* restrict out, size_t n, size_t steps) +{ + size_t m = n - steps; + T* restrict out_a = out + steps; + T* restrict out_b = out; + const T* end_a = out + n; + const T* end_b = out + steps; + + while (out_a != end_a) *out_a++ = *--items; + while (out_b != end_b) *out_b++ = *--items; +} +//>} ; . ../make_fun + + +#undef algo_macro_swap_items + + +#endif + |