return btrp->area_end - btrp->area_start;
}
-size_t btr_pool_filled(struct btr_pool *btrp)
+static size_t btr_pool_filled(struct btr_pool *btrp)
{
if (!btrp->whead)
return btr_pool_size(btrp);
* Return maximal size available for one read. This is
* smaller than the value returned by btr_pool_unused().
*/
-size_t btr_pool_available(struct btr_pool *btrp)
+static size_t btr_pool_available(struct btr_pool *btrp)
{
if (!btrp->whead)
return 0;
return btr_pool_available(btrp);
}
+/**
+ * Get references to buffers pointing to free space of the buffer pool area.
+ *
+ * \param btrp The buffer pool.
+ * \param iov The scatter array.
+ *
+ * \return Zero if the buffer pool is full, one if the free space of the buffer
+ * pool area is available as a single contiguous buffer, two if the free space
+ * consists of two buffers. If this function returns the value n, then n
+ * elements of \a iov are initialized.
+ */
+int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
+{
+ size_t sz, unused;
+ char *buf;
+
+ sz = btr_pool_get_buffer(btrp, &buf);
+ if (sz == 0)
+ return 0;
+ iov[0].iov_len = sz;
+ iov[0].iov_base = buf;
+ unused = btr_pool_unused(btrp);
+ if (sz == unused)
+ return 1;
+ iov[1].iov_len = unused - sz;
+ iov[1].iov_base = btrp->area_start;
+ return 2;
+}
+
/**
* Mark a part of the buffer pool area as allocated.
*
* This function is useful for filters that do not change the contents of the
* buffers at all, like the wav filter or the amp filter if no amplification
* was specified. This function is rather cheap.
+ *
+ * \sa \ref btr_pushdown_one().
*/
void btr_pushdown(struct btr_node *btrn)
{
btr_pushdown_br(br, btrn);
}
-int btr_pushdown_one(struct btr_node *btrn)
+/**
+ * Feed the next buffer of the input queue through the output channel.
+ *
+ * \param btrn The node whose first input queue buffer should be pushed down.
+ *
+ * This works like \ref btr_pushdown() but pushes down only one buffer
+ * reference.
+ */
+void btr_pushdown_one(struct btr_node *btrn)
{
struct btr_buffer_reference *br;
if (list_empty(&btrn->input_queue))
- return 0;
+ return;
br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
btr_pushdown_br(br, btrn);
- return 1;
}
/*
return !btrn->parent;
}
+/**
+ * Find out whether it is OK to change an input buffer.
+ *
+ * \param btrn The buffer tree node to check.
+ *
+ * This is used by filters that produce exactly the same amount of output as
+ * there is input. The amp filter which multiplies each sample by some number
+ * is an example of such a filter. If there are no other nodes in the buffer
+ * tree that read the same input stream (i.e. if \a btrn has no siblings), a
+ * node may modify its input buffer directly and push down the modified buffer
+ * to its children, thereby avoiding to allocate a possibly large additional
+ * buffer.
+ *
+ * Since the buffer tree may change at any time, this function should be called
+ * during each post_select call.
+ *
+ * \return True if \a btrn has no siblings.
+ */
bool btr_inplace_ok(struct btr_node *btrn)
{
if (!btrn->parent)
return br->btrb->size - br->consumed;
}
-size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
+static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
{
if (buf)
*buf = br->btrb->buf + br->consumed;
}
/**
- * Return the size of the largest input queue.
+ * Return number of queued output bytes of a buffer tree node.
*
- * Iterates over all children of the given node.
+ * \param btrn The node whose output queue size should be computed.
+ *
+ * This function iterates over all children of the given node and returns the
+ * size of the largest input queue.
*/
-static size_t btr_bytes_pending(struct btr_node *btrn)
+size_t btr_get_output_queue_size(struct btr_node *btrn)
{
size_t max_size = 0;
struct btr_node *ch;
struct btr_buffer_reference *br, *wbr = NULL;
int num_refs; /* including wrap buffer */
char *buf, *buf1 = NULL, *buf2 = NULL;
- size_t sz, sz1 = 0, sz2 = 0, wsz;
+ size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
br = get_first_input_br(btrn);
if (!br || br_available_bytes(br) >= dest_size)
wbr = br;
if (sz >= dest_size)
return;
+ wb_consumed = br->consumed;
continue;
}
if (!buf1) {
assert(buf2 + sz2 == buf);
sz2 += sz;
next:
- if (sz1 + sz2 >= dest_size)
+ if (sz1 + sz2 >= dest_size + wb_consumed)
break;
}
if (!buf2) /* nothing to do */
* We already have a wrap buffer, but it is too small. It might be
* partially used.
*/
- wsz = br_available_bytes(wbr);
if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
return;
sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
}
}
-bool btr_eof(struct btr_node *btrn)
+static bool btr_eof(struct btr_node *btrn)
{
char *buf;
size_t len = btr_next_buffer(btrn, &buf);
return (len == 0 && btr_no_parent(btrn));
}
-void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
+static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
{
struct btr_node *ch;
const char spaces[] = " ", *space = spaces + 16 - depth;
log_tree_recursively(ch, loglevel, depth + 1);
}
+/**
+ * Write the current buffer (sub-)tree to the log.
+ *
+ * \param btrn Start logging at this node.
+ * \param loglevel Set severity with which the tree should be logged.
+ */
void btr_log_tree(struct btr_node *btrn, int loglevel)
{
return log_tree_recursively(btrn, loglevel, 0);
}
-/*
- * \return \a root if \a name is \p NULL.
+/**
+ * Find the node with the given name in the buffer tree.
+ *
+ * \param name The name of the node to search.
+ * \param root Where to start the search.
+ *
+ * \return A pointer to the node with the given name on success. If \a name is
+ * \p NULL, the function returns \a root. If there is no node with the given
+ * name, \p NULL is returned.
*/
struct btr_node *btr_search_node(const char *name, struct btr_node *root)
{
/** 640K ought to be enough for everybody ;) */
#define BTRN_MAX_PENDING (640 * 1024)
+/**
+ * Return the current state of a buffer tree node.
+ *
+ * \param btrn The node whose state should be queried.
+ * \param min_iqs The minimal input queue size.
+ * \param type The supposed type of \a btrn.
+ *
+ * Most users of the buffer tree subsystem call this function from both
+ * their pre_select and the post_select methods.
+ *
+ * \return Negative if an error condition was detected, zero if there
+ * is nothing to do and positive otherwise.
+ *
+ * Examples:
+ *
+ * - If a non-root node has no parent and an empty input queue, the function
+ * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
+ * -E_BTR_NO_CHILD is returned.
+ *
+ * - If less than \a min_iqs many bytes are available in the input queue and no
+ * EOF condition was detected, the function returns zero.
+ *
+ * - If there's plenty of data left in the input queue of the children of \a
+ * btrn, the function also returns zero in order to bound the memory usage of
+ * the buffer tree.
+ */
int btr_node_status(struct btr_node *btrn, size_t min_iqs,
enum btr_node_type type)
{
if (type != BTR_NT_LEAF) {
if (btr_no_children(btrn))
return -E_BTR_NO_CHILD;
- if (btr_bytes_pending(btrn) > BTRN_MAX_PENDING)
+ if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
return 0;
}
if (type != BTR_NT_ROOT) {
return 1;
}
+/**
+ * Get the time of the first I/O for a buffer tree node.
+ *
+ * \param btrn The node whose I/O time should be obtained.
+ * \param tv Result pointer.
+ *
+ * Mainly useful for the time display of para_audiod.
+ */
void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
{
*tv = btrn->start;
projects / paraslash.git / blobdiff