385 lines
9.4 KiB
C
385 lines
9.4 KiB
C
/* Copyright (C) 2000 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* Handling of arrays that can grow dynamicly. */
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#include "mysys_priv.h"
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#include "m_string.h"
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/*
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Initiate dynamic array
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SYNOPSIS
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init_dynamic_array2()
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array Pointer to an array
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element_size Size of element
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init_buffer Initial buffer pointer
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init_alloc Number of initial elements
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alloc_increment Increment for adding new elements
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DESCRIPTION
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init_dynamic_array() initiates array and allocate space for
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init_alloc eilements.
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Array is usable even if space allocation failed, hence, the
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function never returns TRUE.
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Static buffers must begin immediately after the array structure.
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RETURN VALUE
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FALSE Ok
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*/
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my_bool init_dynamic_array2(DYNAMIC_ARRAY *array, uint element_size,
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void *init_buffer, uint init_alloc,
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uint alloc_increment CALLER_INFO_PROTO)
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{
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DBUG_ENTER("init_dynamic_array");
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if (!alloc_increment)
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{
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alloc_increment=max((8192-MALLOC_OVERHEAD)/element_size,16);
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if (init_alloc > 8 && alloc_increment > init_alloc * 2)
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alloc_increment=init_alloc*2;
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}
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if (!init_alloc)
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{
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init_alloc=alloc_increment;
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init_buffer= 0;
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}
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array->elements=0;
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array->max_element=init_alloc;
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array->alloc_increment=alloc_increment;
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array->size_of_element=element_size;
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if ((array->buffer= init_buffer))
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DBUG_RETURN(FALSE);
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/*
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Since the dynamic array is usable even if allocation fails here malloc
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should not throw an error
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*/
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if (!(array->buffer= (uchar*) my_malloc_ci(element_size*init_alloc, MYF(0))))
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array->max_element=0;
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DBUG_RETURN(FALSE);
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}
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my_bool init_dynamic_array(DYNAMIC_ARRAY *array, uint element_size,
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uint init_alloc,
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uint alloc_increment CALLER_INFO_PROTO)
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{
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/* placeholder to preserve ABI */
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return my_init_dynamic_array_ci(array, element_size, init_alloc,
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alloc_increment);
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}
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/*
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Insert element at the end of array. Allocate memory if needed.
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SYNOPSIS
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insert_dynamic()
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array
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element
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RETURN VALUE
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TRUE Insert failed
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FALSE Ok
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*/
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my_bool insert_dynamic(DYNAMIC_ARRAY *array, uchar* element)
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{
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uchar* buffer;
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if (array->elements == array->max_element)
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{ /* Call only when nessesary */
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if (!(buffer=alloc_dynamic(array)))
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return TRUE;
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}
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else
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{
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buffer=array->buffer+(array->elements * array->size_of_element);
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array->elements++;
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}
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memcpy(buffer,element,(size_t) array->size_of_element);
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return FALSE;
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}
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/*
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Alloc space for next element(s)
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SYNOPSIS
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alloc_dynamic()
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array
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DESCRIPTION
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alloc_dynamic() checks if there is empty space for at least
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one element if not tries to allocate space for alloc_increment
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elements at the end of array.
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RETURN VALUE
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pointer Pointer to empty space for element
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0 Error
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*/
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uchar *alloc_dynamic(DYNAMIC_ARRAY *array)
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{
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if (array->elements == array->max_element)
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{
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char *new_ptr;
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if (array->buffer == (uchar *)(array + 1))
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{
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/*
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In this senerio, the buffer is statically preallocated,
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so we have to create an all-new malloc since we overflowed
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*/
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if (!(new_ptr= (char *) my_malloc((array->max_element+
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array->alloc_increment) *
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array->size_of_element,
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MYF(MY_WME))))
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return 0;
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memcpy(new_ptr, array->buffer,
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array->elements * array->size_of_element);
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}
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else
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if (!(new_ptr=(char*) my_realloc(array->buffer,(array->max_element+
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array->alloc_increment)*
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array->size_of_element,
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MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
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return 0;
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array->buffer= (uchar*) new_ptr;
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array->max_element+=array->alloc_increment;
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}
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return array->buffer+(array->elements++ * array->size_of_element);
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}
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/*
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Pop last element from array.
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SYNOPSIS
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pop_dynamic()
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array
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RETURN VALUE
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pointer Ok
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0 Array is empty
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*/
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uchar *pop_dynamic(DYNAMIC_ARRAY *array)
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{
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if (array->elements)
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return array->buffer+(--array->elements * array->size_of_element);
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return 0;
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}
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/*
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Replace element in array with given element and index
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SYNOPSIS
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set_dynamic()
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array
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element Element to be inserted
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idx Index where element is to be inserted
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DESCRIPTION
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set_dynamic() replaces element in array.
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If idx > max_element insert new element. Allocate memory if needed.
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RETURN VALUE
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TRUE Idx was out of range and allocation of new memory failed
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FALSE Ok
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*/
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my_bool set_dynamic(DYNAMIC_ARRAY *array, uchar* element, uint idx)
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{
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if (idx >= array->elements)
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{
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if (idx >= array->max_element && allocate_dynamic(array, idx))
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return TRUE;
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bzero((uchar*) (array->buffer+array->elements*array->size_of_element),
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(idx - array->elements)*array->size_of_element);
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array->elements=idx+1;
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}
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memcpy(array->buffer+(idx * array->size_of_element),element,
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(size_t) array->size_of_element);
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return FALSE;
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}
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/*
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Ensure that dynamic array has enough elements
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SYNOPSIS
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allocate_dynamic()
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array
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max_elements Numbers of elements that is needed
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NOTES
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Any new allocated element are NOT initialized
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RETURN VALUE
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FALSE Ok
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TRUE Allocation of new memory failed
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*/
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my_bool allocate_dynamic(DYNAMIC_ARRAY *array, uint max_elements)
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{
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if (max_elements >= array->max_element)
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{
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uint size;
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uchar *new_ptr;
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size= (max_elements + array->alloc_increment)/array->alloc_increment;
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size*= array->alloc_increment;
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if (array->buffer == (uchar *)(array + 1))
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{
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/*
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In this senerio, the buffer is statically preallocated,
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so we have to create an all-new malloc since we overflowed
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*/
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if (!(new_ptr= (uchar *) my_malloc(size *
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array->size_of_element,
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MYF(MY_WME))))
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return 0;
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memcpy(new_ptr, array->buffer,
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array->elements * array->size_of_element);
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}
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else
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if (!(new_ptr= (uchar*) my_realloc(array->buffer,size*
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array->size_of_element,
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MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
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return TRUE;
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array->buffer= new_ptr;
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array->max_element= size;
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}
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return FALSE;
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}
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/*
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Get an element from array by given index
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SYNOPSIS
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get_dynamic()
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array
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uchar* Element to be returned. If idx > elements contain zeroes.
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idx Index of element wanted.
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*/
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void get_dynamic(DYNAMIC_ARRAY *array, uchar* element, uint idx)
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{
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if (idx >= array->elements)
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{
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DBUG_PRINT("warning",("To big array idx: %d, array size is %d",
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idx,array->elements));
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bzero(element,array->size_of_element);
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return;
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}
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memcpy(element,array->buffer+idx*array->size_of_element,
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(size_t) array->size_of_element);
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}
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/*
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Empty array by freeing all memory
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SYNOPSIS
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delete_dynamic()
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array Array to be deleted
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*/
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void delete_dynamic(DYNAMIC_ARRAY *array)
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{
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/*
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Just mark as empty if we are using a static buffer
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*/
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if (array->buffer == (uchar *)(array + 1))
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array->elements= 0;
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else
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if (array->buffer)
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{
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my_free(array->buffer,MYF(MY_WME));
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array->buffer=0;
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array->elements=array->max_element=0;
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}
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}
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/*
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Delete element by given index
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SYNOPSIS
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delete_dynamic_element()
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array
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idx Index of element to be deleted
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*/
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void delete_dynamic_element(DYNAMIC_ARRAY *array, uint idx)
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{
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char *ptr= (char*) array->buffer+array->size_of_element*idx;
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array->elements--;
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memmove(ptr,ptr+array->size_of_element,
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(array->elements-idx)*array->size_of_element);
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}
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/*
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Free unused memory
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SYNOPSIS
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freeze_size()
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array Array to be freed
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*/
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void freeze_size(DYNAMIC_ARRAY *array)
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{
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uint elements=max(array->elements,1);
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/*
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Do nothing if we are using a static buffer
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*/
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if (array->buffer == (uchar *)(array + 1))
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return;
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if (array->buffer && array->max_element != elements)
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{
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array->buffer=(uchar*) my_realloc(array->buffer,
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elements*array->size_of_element,
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MYF(MY_WME));
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array->max_element=elements;
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}
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}
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/*
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Get the index of a dynamic element
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SYNOPSIS
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get_index_dynamic()
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array Array
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element Whose element index
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*/
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int get_index_dynamic(DYNAMIC_ARRAY *array, uchar* element)
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{
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size_t ret;
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if (array->buffer > element)
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return -1;
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ret= (element - array->buffer) / array->size_of_element;
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if (ret > array->elements)
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return -1;
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return ret;
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}
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