NET: Add generic I/O buffering logic

1 files changed, 158 insertions, 0 deletions

diff --git a/nuttx/net/iob/iob_concat.c b/nuttx/net/iob/iob_concat.c
new file mode 100644
index 000000000..d7b03e1fc
--- /dev/null
+++ b/nuttx/net/iob/iob_concat.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ * net/iob/iob_concat.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <string.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_concat
+ *
+ * Description:
+ *   Concatenate iob_s chain iob2 to iob1.
+ *
+ ****************************************************************************/
+
+void iob_concat(FAR struct iob_s *iob1, FAR struct iob_s *iob2)
+{
+  unsigned int offset2;
+  unsigned int ncopy;
+  unsigned int navail;
+
+  /* Find the last buffer in the iob1 buffer chain */
+ 
+  while (iob1->io_link.flink)
+    {
+      iob1 = (FAR struct iob_s *)iob1->io_link.flink;
+    }
+
+  /* Then add data to the end of iob1 */
+
+  offset2 = 0;
+  while (iob2)
+    {
+      /* Is the iob1 tail buffer full? */
+
+      if (iob1->io_len >= CONFIG_IOB_BUFSIZE)
+        {
+          /* Yes.. Just connect the chains */
+
+          iob1->io_link.flink = iob2->io_link.flink;
+
+          /* Has the data offset in iob2? */
+
+          if (offset2 > 0)
+            {
+              /* Yes, move the data down and adjust the size */
+
+              iob2->io_len -= offset2;
+              memcpy(iob2->io_data, &iob2->io_data[offset2], iob2->io_len);
+
+              /* Set up to continue packing, but now into iob2 */
+
+              iob1 = iob2;
+              iob2 = (FAR struct iob_s *)iob2->io_link.flink;
+
+              iob1->io_link.flink = NULL;
+              offset2 = 0;
+            }
+          else
+            {
+              /* Otherwise, we are done */
+
+              return;
+            }
+        }
+
+      /* How many bytes can we copy from the source (iob2) */
+
+      ncopy = iob2->io_len - offset2;
+
+      /* Limit the size of the copy to the amount of free space in iob1 */
+
+      navail = CONFIG_IOB_BUFSIZE - iob1->io_len;
+      if (ncopy > navail)
+        {
+          ncopy = navail;
+        }
+
+      /* Copy the data from iob2 into iob1 */
+
+      memcpy(iob1->io_data + iob1->io_len, iob2->io_data, ncopy);
+      iob1->io_len += ncopy;
+      offset2 += ncopy;
+
+      /* Have we consumed all of the data in the iob2 entry? */
+
+      if (offset2 >= iob2->io_len)
+        {
+          /* Yes.. free the iob2 entry and start processing the next I/O
+           * buffer in the iob2 chain.
+           */
+
+          iob2 = iob_free(iob2);
+          offset2 = 0;
+        }
+    }
+}