libswfdec/swfdec_ringbuffer.c

   1
   2 #ifdef HAVE_CONFIG_H
   3 #include "config.h"
   4 #endif
   5
   6 #include <string.h>
   7 #include "swfdec_ringbuffer.h"
   8
   9 SwfdecRingBuffer *
  10 swfdec_ring_buffer_new (guint element_size, guint size)
  11 {
  12   SwfdecRingBuffer *buffer;
  13
  14   g_return_val_if_fail (element_size > 0, NULL);
  15   g_return_val_if_fail (size > 1, NULL);
  16
  17   buffer = g_new0 (SwfdecRingBuffer, 1);
  18   buffer->element_size = element_size;
  19   buffer->size = size;
  20   buffer->data = g_malloc (element_size * size);
  21
  22   return buffer;
  23 }
  24
  25 void
  26 swfdec_ring_buffer_free (SwfdecRingBuffer *buffer)
  27 {
  28   g_return_if_fail (buffer != NULL);
  29
  30   g_free (buffer->data);
  31   g_free (buffer);
  32 }
  33
  34 guint
  35 swfdec_ring_buffer_get_size (SwfdecRingBuffer *buffer)
  36 {
  37   g_return_val_if_fail (buffer != NULL, 0);
  38
  39   return buffer->size;
  40 }
  41
  42 #define GET_ELEMENT(buffer,idx) (buffer->data + buffer->element_size * (idx))
  43 void
  44 swfdec_ring_buffer_set_size (SwfdecRingBuffer *buffer, guint new_size)
  45 {
  46   g_return_if_fail (buffer != NULL);
  47   g_return_if_fail (buffer->size < new_size);
  48
  49   buffer->data = g_realloc (buffer->data, buffer->element_size * new_size);
  50   if (buffer->tail <= buffer->head && buffer->n_elements) {
  51     memmove (GET_ELEMENT (buffer, buffer->head + new_size - buffer->size),
  52         GET_ELEMENT (buffer, buffer->head),
  53         buffer->element_size * (buffer->size - buffer->head));
  54     buffer->head += new_size - buffer->size;
  55   }
  56   buffer->size = new_size;
  57 }
  58
  59 guint
  60 swfdec_ring_buffer_get_n_elements (SwfdecRingBuffer *buffer)
  61 {
  62   g_return_val_if_fail (buffer != NULL, 0);
  63
  64   return buffer->n_elements;
  65 }
  66
  67 gpointer
  68 swfdec_ring_buffer_push (SwfdecRingBuffer *buffer)
  69 {
  70   gpointer ret;
  71
  72   g_return_val_if_fail (buffer != NULL, NULL);
  73
  74   if (buffer->n_elements == buffer->size)
  75     return NULL;
  76
  77   ret = GET_ELEMENT (buffer, buffer->tail);
  78   buffer->tail = (buffer->tail + 1) % buffer->size;
  79   buffer->n_elements++;
  80   return ret;
  81 }
  82
  83 gpointer
  84 swfdec_ring_buffer_pop (SwfdecRingBuffer *buffer)
  85 {
  86   gpointer ret;
  87
  88   g_return_val_if_fail (buffer != NULL, NULL);
  89
  90   if (buffer->n_elements == 0)
  91     return NULL;
  92
  93   ret = GET_ELEMENT (buffer, buffer->head);
  94   buffer->head = (buffer->head + 1) % buffer->size;
  95   buffer->n_elements--;
  96   return ret;
  97 }
  98
  99 gpointer
 100 swfdec_ring_buffer_peek_nth (SwfdecRingBuffer *buffer, guint id)
 101 {
 102   g_return_val_if_fail (buffer != NULL, NULL);
 103   g_return_val_if_fail (id < buffer->n_elements, NULL);
 104
 105   id = (buffer->head + id) % buffer->size;
 106   return GET_ELEMENT (buffer, id);
 107 }