NET: Add generic I/O buffering logic

1 files changed, 129 insertions, 0 deletions

diff --git a/nuttx/net/iob/iob_copyout.c b/nuttx/net/iob/iob_copyout.c
new file mode 100644
index 000000000..5997c7f97
--- /dev/null
+++ b/nuttx/net/iob/iob_copyout.c
@@ -0,0 +1,129 @@
+/****************************************************************************
+ * net/iob/iob_copyout.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 <stdint.h>
+#include <string.h>
+#include <assert.h>
+#include <queue.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifndef MIN
+#  define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_copyout
+ *
+ * Description:
+ *  Copy data 'len' bytes of data into the user buffer starting at 'offset'
+ *  in the I/O buffer.
+ *
+ ****************************************************************************/
+
+void iob_copyout(FAR uint8_t *dest, FAR const struct iob_s *iob,
+                 unsigned int len, unsigned int offset)
+{
+  FAR const uint8_t *src;
+  unsigned int ncopy;
+  unsigned int avail;
+
+  /* Skip to the I/O buffer containing the offset */
+
+  while (offset >= iob->io_len)
+    {
+      offset -= iob->io_len;
+      iob     = (FAR struct iob_s *)iob->io_link.flink;
+    }
+
+  /* Then loop until all of the I/O data is copied to the user buffer */
+
+  while (len > 0)
+    {
+      ASSERT(iob);
+
+      /* Get the source I/O buffer offset address and the amount of data
+       * available from that address.
+       */
+
+      src   = &iob->io_data[offset];
+      avail = iob->io_len - offset;
+
+      /* Copy the whole I/O buffer in to the user buffer */
+
+      ncopy = MIN(avail, len);
+      memcpy(dest, src, ncopy);
+
+      /* Adjust the total length of the copy and the destination address in
+       * the user buffer.
+       */
+
+      len  -= ncopy;
+      dest += ncopy;
+
+      /* Skip to the next I/O buffer in the chain */
+
+      iob = (FAR struct iob_s *)iob->io_link.flink;
+      offset = 0;
+    }
+}