snapraid/tommyds/tommyarray.h
2019-01-07 14:41:48 +01:00

147 lines
4.4 KiB
C

/*
* Copyright (c) 2011, Andrea Mazzoleni. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/** \file
* Dynamic array based on segments of exponential growing size.
*
* This array is able to grow dynamically upon request, without any reallocation.
*
* The grow operation involves an allocation of a new array segment, without reallocating
* the already used memory, and then not increasing the heap fragmentation.
* This also implies that the address of the stored elements never change.
*
* Allocated segments grow in size exponentially.
*/
#ifndef __TOMMYARRAY_H
#define __TOMMYARRAY_H
#include "tommytypes.h"
#include <assert.h> /* for assert */
/******************************************************************************/
/* array */
/**
* Initial and minimal size of the array expressed as a power of 2.
* The initial size is 2^TOMMY_ARRAY_BIT.
*/
#define TOMMY_ARRAY_BIT 6
/**
* Array container type.
* \note Don't use internal fields directly, but access the container only using functions.
*/
typedef struct tommy_array_struct {
void** bucket[TOMMY_SIZE_BIT]; /**< Dynamic array of buckets. */
tommy_size_t bucket_max; /**< Number of buckets. */
tommy_size_t count; /**< Number of initialized elements in the array. */
tommy_uint_t bucket_bit; /**< Bits used in the bit mask. */
} tommy_array;
/**
* Initializes the array.
*/
void tommy_array_init(tommy_array* array);
/**
* Deinitializes the array.
*/
void tommy_array_done(tommy_array* array);
/**
* Grows the size up to the specified value.
* All the new elements in the array are initialized with the 0 value.
*/
void tommy_array_grow(tommy_array* array, tommy_size_t size);
/**
* Gets a reference of the element at the specified position.
* You must be sure that space for this position is already
* allocated calling tommy_array_grow().
*/
tommy_inline void** tommy_array_ref(tommy_array* array, tommy_size_t pos)
{
tommy_uint_t bsr;
assert(pos < array->count);
/* get the highest bit set, in case of all 0, return 0 */
bsr = tommy_ilog2(pos | 1);
return &array->bucket[bsr][pos];
}
/**
* Sets the element at the specified position.
* You must be sure that space for this position is already
* allocated calling tommy_array_grow().
*/
tommy_inline void tommy_array_set(tommy_array* array, tommy_size_t pos, void* element)
{
*tommy_array_ref(array, pos) = element;
}
/**
* Gets the element at the specified position.
* You must be sure that space for this position is already
* allocated calling tommy_array_grow().
*/
tommy_inline void* tommy_array_get(tommy_array* array, tommy_size_t pos)
{
return *tommy_array_ref(array, pos);
}
/**
* Grows and inserts a new element at the end of the array.
*/
tommy_inline void tommy_array_insert(tommy_array* array, void* element)
{
tommy_size_t pos = array->count;
tommy_array_grow(array, pos + 1);
tommy_array_set(array, pos, element);
}
/**
* Gets the initialized size of the array.
*/
tommy_inline tommy_size_t tommy_array_size(tommy_array* array)
{
return array->count;
}
/**
* Gets the size of allocated memory.
*/
tommy_size_t tommy_array_memory_usage(tommy_array* array);
#endif