swfdec/swfdec_ringbuffer.c

   1 /* Swfdec
   2  * Copyright (C) 2007 Benjamin Otte <otte@gnome.org>
   3  *
   4  * This library is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public
   6  * License as published by the Free Software Foundation; either
   7  * version 2.1 of the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this library; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  * Boston, MA  02110-1301  USA
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include <string.h>
  25 #include "swfdec_ringbuffer.h"
  26
  27 SwfdecRingBuffer *
  28 swfdec_ring_buffer_new (guint element_size, guint size)
  29 {
  30   SwfdecRingBuffer *buffer;
  31
  32   g_return_val_if_fail (element_size > 0, NULL);
  33   g_return_val_if_fail (size > 1, NULL);
  34
  35   buffer = g_new0 (SwfdecRingBuffer, 1);
  36   buffer->element_size = element_size;
  37   buffer->size = size;
  38   buffer->data = g_malloc (element_size * size);
  39
  40   return buffer;
  41 }
  42
  43 void
  44 swfdec_ring_buffer_free (SwfdecRingBuffer *buffer)
  45 {
  46   g_return_if_fail (buffer != NULL);
  47
  48   g_free (buffer->data);
  49   g_free (buffer);
  50 }
  51
  52 guint
  53 swfdec_ring_buffer_get_size (SwfdecRingBuffer *buffer)
  54 {
  55   g_return_val_if_fail (buffer != NULL, 0);
  56
  57   return buffer->size;
  58 }
  59
  60 #define GET_ELEMENT(buffer,idx) (buffer->data + buffer->element_size * (idx))
  61 void
  62 swfdec_ring_buffer_set_size (SwfdecRingBuffer *buffer, guint new_size)
  63 {
  64   g_return_if_fail (buffer != NULL);
  65   g_return_if_fail (buffer->size < new_size);
  66
  67   buffer->data = g_realloc (buffer->data, buffer->element_size * new_size);
  68   if (buffer->tail <= buffer->head && buffer->n_elements) {
  69     memmove (GET_ELEMENT (buffer, buffer->head + new_size - buffer->size),
  70         GET_ELEMENT (buffer, buffer->head),
  71         buffer->element_size * (buffer->size - buffer->head));
  72     buffer->head += new_size - buffer->size;
  73   }
  74   buffer->size = new_size;
  75 }
  76
  77 guint
  78 swfdec_ring_buffer_get_n_elements (SwfdecRingBuffer *buffer)
  79 {
  80   g_return_val_if_fail (buffer != NULL, 0);
  81
  82   return buffer->n_elements;
  83 }
  84
  85 gpointer
  86 swfdec_ring_buffer_push (SwfdecRingBuffer *buffer)
  87 {
  88   gpointer ret;
  89
  90   g_return_val_if_fail (buffer != NULL, NULL);
  91
  92   if (buffer->n_elements == buffer->size)
  93     return NULL;
  94
  95   ret = GET_ELEMENT (buffer, buffer->tail);
  96   buffer->tail = (buffer->tail + 1) % buffer->size;
  97   buffer->n_elements++;
  98   return ret;
  99 }
 100
 101 gpointer
 102 swfdec_ring_buffer_pop (SwfdecRingBuffer *buffer)
 103 {
 104   gpointer ret;
 105
 106   g_return_val_if_fail (buffer != NULL, NULL);
 107
 108   if (buffer->n_elements == 0)
 109     return NULL;
 110
 111   ret = GET_ELEMENT (buffer, buffer->head);
 112   buffer->head = (buffer->head + 1) % buffer->size;
 113   buffer->n_elements--;
 114   return ret;
 115 }
 116
 117 gpointer
 118 swfdec_ring_buffer_peek_nth (SwfdecRingBuffer *buffer, guint id)
 119 {
 120   g_return_val_if_fail (buffer != NULL, NULL);
 121   g_return_val_if_fail (id < buffer->n_elements, NULL);
 122
 123   id = (buffer->head + id) % buffer->size;
 124   return GET_ELEMENT (buffer, id);
 125 }