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author | Gregory Nutt <gnutt@nuttx.org> | 2014-06-03 12:41:34 -0600 |
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committer | Gregory Nutt <gnutt@nuttx.org> | 2014-06-03 12:41:34 -0600 |
commit | 6d7446a054fdfa9bed57d003e085175a5ed89b92 (patch) | |
tree | d703850da16c7635da749542ff387681026b0e2f /nuttx/net/iob/iob_copyout.c | |
parent | e8f16d76fb1dc7ec47dde9558a59472223f68547 (diff) | |
download | px4-nuttx-6d7446a054fdfa9bed57d003e085175a5ed89b92.tar.gz px4-nuttx-6d7446a054fdfa9bed57d003e085175a5ed89b92.tar.bz2 px4-nuttx-6d7446a054fdfa9bed57d003e085175a5ed89b92.zip |
NET: Add generic I/O buffering logic
Diffstat (limited to 'nuttx/net/iob/iob_copyout.c')
-rw-r--r-- | nuttx/net/iob/iob_copyout.c | 129 |
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; + } +} |