projects / apple / xnu.git / blame
| Commit | Line | Data |
|---|---|---|
| 13fec989 A |
1 | <h2>device_read_async</h2> |
| 2 | <hr> | |
| 3 | <p> | |
| 4 | <strong>System Trap</strong> - Read a sequence of bytes from a device object. | |
| 5 | <h3>SYNOPSIS</h3> | |
| 6 | <pre> | |
| 7 | <strong>kern_return_t device_read_async</strong> | |
| 8 | <strong>(mach_port_t</strong> <var>device</var>, | |
| 9 | <strong>mach_port_t</strong> <var>queue</var>, | |
| 10 | <strong>mach_port_t</strong> <var>request_id</var>, | |
| 11 | <strong>dev_mode_t</strong> <var>mode</var>, | |
| 12 | <strong>recnum_t</strong> <var>recnum</var>, | |
| 13 | <strong>io_buf_len_t</strong> <var>bytes_wanted</var><strong>);</strong> | |
| 14 | </pre> | |
| 15 | <h3>PARAMETERS</h3> | |
| 16 | <dl> | |
| 17 | <p> | |
| 18 | <dt> <var>device</var> | |
| 19 | <dd> | |
| 20 | [in device send right] A device port to the device to be read. | |
| 21 | <p> | |
| 22 | <dt> <var>queue</var> | |
| 23 | <dd> | |
| 24 | [in io_done queue send right] The port returned from | |
| 25 | io_done_queue_create. | |
| 26 | <p> | |
| 27 | <dt> <var>request_id</var> | |
| 28 | <dd> | |
| 29 | [in send right] An unique request identifier that will be passed back as | |
| 30 | part of the io_done_result structure. | |
| 31 | <p> | |
| 32 | <dt> <var>mode</var> | |
| 33 | <dd> | |
| 34 | [in scalar] I/O mode value. Meaningful options are: | |
| 35 | <p> | |
| 36 | <dl> | |
| 37 | <dt> <strong>D_NOWAIT</strong> | |
| 38 | <dd> | |
| 39 | Do not wait if data is unavailable. | |
| 40 | </dl> | |
| 41 | <p> | |
| 42 | <dt> <var>recnum</var> | |
| 43 | <dd> | |
| 44 | [in scalar] Record number to be read. | |
| 45 | <p> | |
| 46 | <dt> <var>bytes_wanted</var> | |
| 47 | <dd> | |
| 48 | [in scalar] Size of data transfer. | |
| 49 | </dl> | |
| 50 | <h3>DESCRIPTION</h3> | |
| 51 | <p> | |
| 52 | The <strong>device_read_async</strong> interface enqueues a read operation for a | |
| 53 | sequence of bytes from a device object. The meaning of recnum as well | |
| 54 | as the specific operation performed is device dependent. | |
| 55 | <h3>RETURN VALUES</h3> | |
| 56 | <dl> | |
| 57 | <strong>device_read_async</strong> returns only invalid parameter errors. | |
| 58 | <dd> | |
| 59 | </dl> | |
| 60 | <h3>RELATED INFORMATION</h3> | |
| 61 | <p> | |
| 62 | Functions: | |
| 63 | <a href="device_read_async_inband.html"><strong>device_read_async_inband</strong></a>, | |
| 64 | <a href="DR_overwrite_async.html"><strong>device_read_overwrite_async</strong></a>, | |
| 65 | <a href="device_write_async.html"><strong>device_write_async</strong></a>, | |
| 66 | <a href="device_write_async_inband.html"><strong>device_write_async_inband</strong></a>, | |
| 67 | <a href="io_done_queue_create.html"><strong>io_done_queue_create</strong></a>. |