array.c   [plain text]

/* Copyright Abandoned 1996 TCX DataKonsult AB & Monty Program KB & Detron HB 
This file is public domain and comes with NO WARRANTY of any kind */

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

#if defined(WIN32) || defined(__WIN__)
#undef SAFEMALLOC				/* Problems with threads */
#endif

#include "mysys_priv.h"
#include "m_string.h"

/*
  Initiate array and alloc space for init_alloc elements. Array is usable
  even if space allocation failed
*/

my_bool init_dynamic_array(DYNAMIC_ARRAY *array, uint element_size,
			   uint init_alloc, uint alloc_increment)
{
  DBUG_ENTER("init_dynamic_array");
  if (!alloc_increment)
  { 
    alloc_increment=max((8192-MALLOC_OVERHEAD)/element_size,16);
    if (init_alloc > 8 && alloc_increment > init_alloc * 2)
      alloc_increment=init_alloc*2;
  }

  if (!init_alloc)
    init_alloc=alloc_increment;
  array->elements=0;
  array->max_element=init_alloc;
  array->alloc_increment=alloc_increment;
  array->size_of_element=element_size;
  if (!(array->buffer=(char*) my_malloc(element_size*init_alloc,MYF(MY_WME))))
  {
    array->max_element=0;
    DBUG_RETURN(TRUE);
  }
  DBUG_RETURN(FALSE);
}


my_bool insert_dynamic(DYNAMIC_ARRAY *array, gptr element)
{
  gptr buffer;
  if (array->elements == array->max_element)
  {						/* Call only when nessesary */
    if (!(buffer=alloc_dynamic(array)))
      return TRUE;
  }
  else
  {
    buffer=array->buffer+(array->elements * array->size_of_element);
    array->elements++;
  }
  memcpy(buffer,element,(size_t) array->size_of_element);
  return FALSE;
}


	/* Alloc room for one element */

byte *alloc_dynamic(DYNAMIC_ARRAY *array)
{
  if (array->elements == array->max_element)
  {
    char *new_ptr;
    if (!(new_ptr=(char*) my_realloc(array->buffer,(array->max_element+
				     array->alloc_increment)*
				     array->size_of_element,
				     MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
      return 0;
    array->buffer=new_ptr;
    array->max_element+=array->alloc_increment;
  }
  return array->buffer+(array->elements++ * array->size_of_element);
}


	/* remove last element from array and return it */

byte *pop_dynamic(DYNAMIC_ARRAY *array)
{
  if (array->elements)
    return array->buffer+(--array->elements * array->size_of_element);
  return 0;
}


my_bool set_dynamic(DYNAMIC_ARRAY *array, gptr element, uint idx)
{
  if (idx >= array->elements)
  {
    if (idx >= array->max_element)
    {
      uint size;
      char *new_ptr;
      size=(idx+array->alloc_increment)/array->alloc_increment;
      size*= array->alloc_increment;
      if (!(new_ptr=(char*) my_realloc(array->buffer,size*
				       array->size_of_element,
				       MYF(MY_WME | MY_ALLOW_ZERO_PTR))))
	return TRUE;
      array->buffer=new_ptr;
      array->max_element=size;
    }
    bzero((gptr) (array->buffer+array->elements*array->size_of_element),
	  (idx - array->elements)*array->size_of_element);
    array->elements=idx+1;
  }
  memcpy(array->buffer+(idx * array->size_of_element),element,
	 (size_t) array->size_of_element);
  return FALSE;
}


void get_dynamic(DYNAMIC_ARRAY *array, gptr element, uint idx)
{
  if (idx >= array->elements)
  {
    DBUG_PRINT("warning",("To big array idx: %d, array size is %d",
			  idx,array->elements));
    bzero(element,array->size_of_element);
    return;
  }
  memcpy(element,array->buffer+idx*array->size_of_element,
	 (size_t) array->size_of_element);
}


void delete_dynamic(DYNAMIC_ARRAY *array)
{
  if (array->buffer)
  {
    my_free(array->buffer,MYF(MY_WME));
    array->buffer=0;
    array->elements=array->max_element=0;
  }
}


void delete_dynamic_element(DYNAMIC_ARRAY *array, uint idx)
{
  char *ptr=array->buffer+array->size_of_element*idx;
  array->elements--;
  memmove(ptr,ptr+array->size_of_element,
	  (array->elements-idx)*array->size_of_element);
}


void freeze_size(DYNAMIC_ARRAY *array)
{
  uint elements=max(array->elements,1);

  if (array->buffer && array->max_element != elements)
  {
    array->buffer=(char*) my_realloc(array->buffer,
				     elements*array->size_of_element,
				     MYF(MY_WME));
    array->max_element=elements;
  }
}