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121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
// SPDX-License-Identifier: BSD-2-Clause
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// Copyright (C) 2011 Andrea Mazzoleni
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/** \file
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* Dynamic array based on segments of exponentially growing size.
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*
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* This array is able to grow dynamically upon request, without any reallocation.
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*
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* The grow operation involves an allocation of a new array segment, without reallocating
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* the already used memory, and thus **not increasing** the heap fragmentation.
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* This also implies that the address of the stored elements never change.
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*
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* Allocated segments grow in size exponentially.
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*/
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#ifndef __TOMMYARRAY_H
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#define __TOMMYARRAY_H
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#include "tommytypes.h"
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#include <assert.h> /* for assert */
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/******************************************************************************/
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/* array */
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/**
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* Initial and minimal size of the array expressed as a power of 2.
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* The initial size is 2^TOMMY_ARRAY_BIT.
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*/
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#define TOMMY_ARRAY_BIT 6
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/**
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* Array container type.
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* \note Don't use internal fields directly, but access the container only using functions.
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*/
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typedef struct tommy_array_struct {
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void** bucket[TOMMY_SIZE_BIT]; /**< Dynamic array of buckets. */
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tommy_size_t bucket_max; /**< Number of buckets. */
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tommy_size_t count; /**< Number of initialized elements in the array. */
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tommy_uint_t bucket_bit; /**< Bits used in the bit mask. */
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} tommy_array;
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/**
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* Initializes the array.
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*/
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TOMMY_API void tommy_array_init(tommy_array* array);
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/**
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* Deinitializes the array.
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*/
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TOMMY_API void tommy_array_done(tommy_array* array);
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/**
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* Grows the size up to the specified value.
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* All the new elements in the array are initialized with the 0 value.
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*/
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TOMMY_API void tommy_array_grow(tommy_array* array, tommy_size_t size);
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/**
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* Gets a reference of the element at the specified position.
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* You must be sure that space for this position is already
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* allocated calling tommy_array_grow().
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*/
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tommy_inline void** tommy_array_ref(tommy_array* array, tommy_size_t pos)
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{
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tommy_uint_t bsr;
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assert(pos < array->count);
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/* get the highest bit set, in case of all 0, return 0 */
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bsr = tommy_ilog2(pos | 1);
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return &array->bucket[bsr][pos];
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}
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/**
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* Sets the element at the specified position.
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* You must be sure that space for this position is already
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* allocated calling tommy_array_grow().
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*/
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tommy_inline void tommy_array_set(tommy_array* array, tommy_size_t pos, void* element)
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{
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*tommy_array_ref(array, pos) = element;
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}
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/**
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* Gets the element at the specified position.
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* You must be sure that space for this position is already
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* allocated calling tommy_array_grow().
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*/
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tommy_inline void* tommy_array_get(tommy_array* array, tommy_size_t pos)
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{
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return *tommy_array_ref(array, pos);
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}
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/**
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* Grows and inserts a new element at the end of the array.
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*/
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tommy_inline void tommy_array_insert(tommy_array* array, void* element)
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{
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tommy_size_t pos = array->count;
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tommy_array_grow(array, pos + 1);
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tommy_array_set(array, pos, element);
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}
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/**
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* Gets the initialized size of the array.
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*/
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tommy_inline tommy_size_t tommy_array_size(tommy_array* array)
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{
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return array->count;
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}
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/**
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* Gets the size of allocated memory.
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*/
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TOMMY_API tommy_size_t tommy_array_memory_usage(tommy_array* array);
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#endif
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