~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   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; version 2 of the License.

   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, write to the Free Software

   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/* Handling of arrays that can grow dynamicly. */

#include <config.h>

#include <algorithm>

#include <drizzled/dynamic_array.h>

#include <drizzled/internal/my_sys.h>

using namespace std;

namespace drizzled {

/*

  Initiate dynamic array

  SYNOPSIS

    init_dynamic_array2()

      array		Pointer to an array

      element_size	Size of element

      init_buffer       Initial buffer pointer

      init_alloc	Number of initial elements

      alloc_increment	Increment for adding new elements

  DESCRIPTION

    init_dynamic_array() initiates array and allocate space for

    init_alloc eilements.

    Array is usable even if space allocation failed.

    Static buffers must begin immediately after the array structure.

  RETURN VALUE

    true	malloc() failed

    false	Ok

*/

void init_dynamic_array2(DYNAMIC_ARRAY *array, uint32_t element_size,

                            void *init_buffer, uint32_t init_alloc,

                            uint32_t alloc_increment)

{

  if (!alloc_increment)

  {

    alloc_increment=max((8192-MALLOC_OVERHEAD)/element_size,16U);

    if (init_alloc > 8 && alloc_increment > init_alloc * 2)

      alloc_increment=init_alloc*2;

  }

  if (!init_alloc)

  {

    init_alloc=alloc_increment;

    init_buffer= 0;

  }

  array->set_size(0);

  array->max_element=init_alloc;

  array->alloc_increment=alloc_increment;

  array->size_of_element=element_size;

  if ((array->buffer= (unsigned char*) init_buffer))

    return;

  array->buffer= (unsigned char*) malloc(element_size*init_alloc);

}

/*

  Insert element at the end of array. Allocate memory if needed.

  SYNOPSIS

    insert_dynamic()

      array

      element

  RETURN VALUE

    true	Insert failed

    false	Ok

*/

static void insert_dynamic(DYNAMIC_ARRAY *array, void* element)

{

  unsigned char* buffer;

  if (array->size() == array->max_element)

    buffer= alloc_dynamic(array);

  else

  {

    buffer= array->buffer+(array->size() * array->size_of_element);

    array->set_size(array->size() + 1);

  }

  memcpy(buffer,element, array->size_of_element);

}

void DYNAMIC_ARRAY::push_back(void* v)

{

  insert_dynamic(this, v);

}

/*

  Alloc space for next element(s)

  SYNOPSIS

    alloc_dynamic()

      array

  DESCRIPTION

    alloc_dynamic() checks if there is empty space for at least

    one element if not tries to allocate space for alloc_increment

    elements at the end of array.

  RETURN VALUE

    pointer	Pointer to empty space for element

    0		Error

*/

unsigned char *alloc_dynamic(DYNAMIC_ARRAY *array)

{

  if (array->size() == array->max_element)

  {

    char *new_ptr;

    if (array->buffer == (unsigned char *)(array + 1))

    {

      /*

        In this senerio, the buffer is statically preallocated,

        so we have to create an all-new malloc since we overflowed

      */

      new_ptr= (char*) malloc((array->max_element + array->alloc_increment) * array->size_of_element);

      memcpy(new_ptr, array->buffer, array->size() * array->size_of_element);

    }

    else 

      new_ptr= (char*) realloc(array->buffer, (array->max_element + array->alloc_increment) * array->size_of_element);

    array->buffer= (unsigned char*) new_ptr;

    array->max_element+=array->alloc_increment;

  }

  array->set_size(array->size() + 1);

  return array->buffer + ((array->size() - 1) * array->size_of_element);

}

/*

  Empty array by freeing all memory

  SYNOPSIS

    delete_dynamic()

      array	Array to be deleted

*/

void delete_dynamic(DYNAMIC_ARRAY *array)

{

  /*

    Just mark as empty if we are using a static buffer

  */

  if (array->buffer == (unsigned char *)(array + 1))

    array->set_size(0);

  else

  if (array->buffer)

  {

    free(array->buffer);

    array->buffer=0;

    array->set_size(array->max_element=0);

  }

}

} /* namespace drizzled */