osfmk/man/device_read.html

   1 <h2>device_read</h2>
   2 <hr>
   3 <p>
   4 <strong>Function</strong> - Read a sequence of bytes from a specific device.
   5 <h3>SYNOPSIS</h3>
   6 <pre>
   7 <strong>#include&ltdevice/device.h&gt</strong>
   8
   9 <strong>kern_return_t   device_read</strong>
  10                 <strong>(device_t</strong>                                <var>device</var>,
  11                  <strong>mach_port_t</strong>                         <var>reply_port</var>,
  12                  <strong>dev_mode_t</strong>                                <var>mode</var>,
  13                  <strong>recnum_t</strong>                                <var>recnum</var>,
  14                  <strong>io_buf_len_t</strong>                      <var>bytes_wanted</var>,
  15                  <strong>io_buf_ptr_t</strong>                      <var>io_buf_ptr_t</var>,
  16                  <strong>mach_msg_type_number_t</strong>  <var>mach_msg_type_number_t</var><strong>);</strong>
  17
  18
  19 <strong>#include&ltdevice/device_request.h&gt</strong>
  20
  21 <strong>kern_return_t   device_read_request</strong>
  22                 <strong>(mach_port_t</strong>                            <var>device</var>,
  23                  <strong>mach_port_t</strong>                        <var>reply_port</var>,
  24                  <strong>dev_mode_t</strong>                                <var>mode</var>,
  25                  <strong>recnum_t</strong>                                <var>recnum</var>,
  26                  <strong>io_buf_len_t</strong>                      <var>bytes_wanted</var><strong>);</strong>
  27
  28
  29
  30 <strong>kern_return_t   ds_device_read_reply</strong>
  31                 <strong>(mach_port_t</strong>                         <var>reply_port</var>,
  32                  <strong>kern_return_t</strong>                      <var>return_code</var>,
  33                  <strong>io_buf_ptr_t</strong>                              <var>data</var>,
  34                  <strong>mach_msg_type_number_t</strong>              <var>data_count</var><strong>);</strong>
  35 </pre>
  36 <h3>PARAMETERS</h3>
  37 <dl>
  38 <p>
  39 <dt> <var>device</var>
  40 <dd>
  41 [in device send right]
  42 A device port to the device to be read.
  43 <p>
  44 <dt> <var>reply_port</var>
  45 <dd>
  46 [in reply receive (to be converted to send-once) right]
  47 The port to
  48 which the reply message is to be sent.
  49 <p>
  50 <dt> <var>mode</var>
  51 <dd>
  52 [in scalar]
  53 I/O mode value.  Meaningful options are:
  54 <dl>
  55 <p>
  56 <dt> <strong>D_NOWAIT</strong>
  57 <dd>
  58 Do not wait if data is unavailable.
  59 </dl>
  60 <p>
  61 <dt> <var>recnum</var>
  62 <dd>
  63 [in scalar]
  64 Record number to be read.
  65 <p>
  66 <dt> <var>bytes_wanted</var>
  67 <dd>
  68 [in scalar]
  69 Size of data transfer.
  70 <p>
  71 <dt> <var>return_code</var>
  72 <dd>
  73 [in scalar]
  74 The return status code from the read.
  75 <p>
  76 <dt> <var>data</var>
  77 <dd>
  78 [out pointer to dynamic array of bytes, in for asynchronous form]
  79 Returned data bytes.
  80 <p>
  81 <dt> <var>data_count</var>
  82 <dd>
  83 [out scalar, in for asynchronous form]
  84 Number of returned data bytes.
  85 </dl>
  86 <h3>DESCRIPTION</h3>
  87 <p>
  88 The <strong>device_read</strong> function reads a sequence of bytes
  89 from a device object.  The
  90 meaning of <var>recnum</var> as well as the specific operation performed is device
  91 dependent.
  92 <h3>RETURN VALUES</h3>
  93 <p>
  94 Only generic errors apply.
  95 <h3>RELATED INFORMATION</h3>
  96 <p>
  97 Functions:
  98 <a href="device_read_inband.html"><strong>device_read_inband</strong></a>,
  99 <a href="device_read_overwrite.html"><strong>device_read_overwrite</strong></a>,
 100 <a href="device_reply_server.html"><strong>device_reply_server</strong></a>.