## device_write

Function - Write a sequence of bytes to a specific device.

### SYNOPSIS

    #include<device/device.h>

    kern_return_t   device_write
                    (device_t                                device,
                     mach_port_t                         reply_port,
                     dev_mode_t                                mode,
                     recnum_t                                recnum,
                     io_buf_ptr_t                              data,
                     mach_msg_type_number_t              data_count,
                     io_buf_len_t                      io_buf_len_t);

    #include<device/device_request.h>

    kern_return_t   device_write_request
                    (mach_port_t                             device,
                     mach_port_t                         reply_port,
                     dev_mode_t                                mode,
                     recnum_t                                recnum,
                     io_buf_ptr_t                              data,
                     mach_msg_type_number_t              data_count);

    kern_return_t   ds_device_write_reply
                    (mach_port_t                         reply_port,
                     kern_return_t                      return_code,
                     io_buf_len_t                     bytes_written);

### PARAMETERS

device
  [in device send right] A device port to the device to be written.

reply_port
  [in reply receive (to be converted to send-once) right] The port to which the reply message is to be sent.

mode
  [in scalar] I/O mode value. Meaningful options are:

  D_NOWAIT
    Do not wait for I/O completion.

recnum
  [in scalar] Record number to be written.

data
  [pointer to in array of bytes] Data bytes to be written.

data_count
  [in scalar] Number of data bytes to be written.

return_code
  [in scalar] The return status code from the write.

bytes_written
  [out scalar, in for asynchronous form] Size of data transfer.

### DESCRIPTION

The device_write function writes a sequence of bytes to a device object. The meaning of recnum as well as the specific operation performed is device dependent.

### RETURN VALUES

Only generic errors apply.

### RELATED INFORMATION

Functions: device_write_inband, device_reply_server.