gtk2/glib/garray.c

/* GLIB - Library of useful routines for C programming
 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <string.h>
#include "glib.h"


#define MIN_ARRAY_SIZE  16


typedef struct _GRealArray  GRealArray;

struct _GRealArray
{
  guint8 *data;
  guint   len;
  guint   alloc;
  guint   zero_terminated;
};


static gint g_nearest_pow        (gint        num);
static void g_array_maybe_expand (GRealArray *array,
				  gint        len);


static GMemChunk *array_mem_chunk = NULL;


GArray*
g_array_new (zero_terminated)
{
  GRealArray *array;

  if (!array_mem_chunk)
    array_mem_chunk = g_mem_chunk_new ("array mem chunk",
				       sizeof (GRealArray),
				       1024, G_ALLOC_AND_FREE);

  array = g_chunk_new (GRealArray, array_mem_chunk);

  array->data = NULL;
  array->len = 0;
  array->alloc = 0;
  array->zero_terminated = (zero_terminated ? 1 : 0);

  return (GArray*) array;
}

void
g_array_free (GArray *array,
	      gint    free_segment)
{
  if (free_segment)
    g_free (array->data);

  g_mem_chunk_free (array_mem_chunk, array);
}

GArray*
g_rarray_append (GArray   *array,
		 gpointer  data,
		 gint      size)
{
  g_array_maybe_expand ((GRealArray*) array, size);

  memcpy (array->data + array->len, data, size);

  array->len += size;

  return array;
}

GArray*
g_rarray_prepend (GArray   *array,
		  gpointer  data,
		  gint      size)
{
  g_array_maybe_expand ((GRealArray*) array, size);

  g_memmove (array->data + size, array->data, array->len);
  memcpy (array->data, data, size);

  array->len += size;

  return array;
}

GArray*
g_rarray_truncate (GArray *array,
		   gint    length,
		   gint    size)
{
  if (array->data)
    memset (array->data + length * size, 0, size);
  array->len = length;
  return array;
}


static gint
g_nearest_pow (gint num)
{
  gint n = 1;

  while (n < num)
    n <<= 1;

  return n;
}

static void
g_array_maybe_expand (GRealArray *array,
		      gint        len)
{
  guint old_alloc;

  if ((array->len + len) > array->alloc)
    {
      old_alloc = array->alloc;

      array->alloc = g_nearest_pow (array->len + array->zero_terminated + len);
      array->alloc = MAX (array->alloc, MIN_ARRAY_SIZE);
      array->data = g_realloc (array->data, array->alloc);

      memset (array->data + old_alloc, 0, array->alloc - old_alloc);
    }
}