mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
62 lines
1.7 KiB
62 lines
1.7 KiB
.. SPDX-License-Identifier: GPL-2.0 |
|
|
|
Digital TV Common functions |
|
--------------------------- |
|
|
|
Math functions |
|
~~~~~~~~~~~~~~ |
|
|
|
Provide some commonly-used math functions, usually required in order to |
|
estimate signal strength and signal to noise measurements in dB. |
|
|
|
.. kernel-doc:: include/media/dvb_math.h |
|
|
|
|
|
DVB devices |
|
~~~~~~~~~~~ |
|
|
|
Those functions are responsible for handling the DVB device nodes. |
|
|
|
.. kernel-doc:: include/media/dvbdev.h |
|
|
|
Digital TV Ring buffer |
|
~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
Those routines implement ring buffers used to handle digital TV data and |
|
copy it from/to userspace. |
|
|
|
.. note:: |
|
|
|
1) For performance reasons read and write routines don't check buffer sizes |
|
and/or number of bytes free/available. This has to be done before these |
|
routines are called. For example: |
|
|
|
.. code-block:: c |
|
|
|
/* write @buflen: bytes */ |
|
free = dvb_ringbuffer_free(rbuf); |
|
if (free >= buflen) |
|
count = dvb_ringbuffer_write(rbuf, buffer, buflen); |
|
else |
|
/* do something */ |
|
|
|
/* read min. 1000, max. @bufsize: bytes */ |
|
avail = dvb_ringbuffer_avail(rbuf); |
|
if (avail >= 1000) |
|
count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize)); |
|
else |
|
/* do something */ |
|
|
|
2) If there is exactly one reader and one writer, there is no need |
|
to lock read or write operations. |
|
Two or more readers must be locked against each other. |
|
Flushing the buffer counts as a read operation. |
|
Resetting the buffer counts as a read and write operation. |
|
Two or more writers must be locked against each other. |
|
|
|
.. kernel-doc:: include/media/dvb_ringbuffer.h |
|
|
|
Digital TV VB2 handler |
|
~~~~~~~~~~~~~~~~~~~~~~ |
|
|
|
.. kernel-doc:: include/media/dvb_vb2.h
|
|
|