0001 .. SPDX-License-Identifier: GPL-2.0
0002
0003 Digital TV Common functions
0004 ---------------------------
0005
0006 Math functions
0007 ~~~~~~~~~~~~~~
0008
0009 Provide some commonly-used math functions, usually required in order to
0010 estimate signal strength and signal to noise measurements in dB.
0011
0012 .. kernel-doc:: include/media/dvb_math.h
0013
0014
0015 DVB devices
0016 ~~~~~~~~~~~
0017
0018 Those functions are responsible for handling the DVB device nodes.
0019
0020 .. kernel-doc:: include/media/dvbdev.h
0021
0022 Digital TV Ring buffer
0023 ~~~~~~~~~~~~~~~~~~~~~~
0024
0025 Those routines implement ring buffers used to handle digital TV data and
0026 copy it from/to userspace.
0027
0028 .. note::
0029
0030 1) For performance reasons read and write routines don't check buffer sizes
0031 and/or number of bytes free/available. This has to be done before these
0032 routines are called. For example:
0033
0034 .. code-block:: c
0035
0036 /* write @buflen: bytes */
0037 free = dvb_ringbuffer_free(rbuf);
0038 if (free >= buflen)
0039 count = dvb_ringbuffer_write(rbuf, buffer, buflen);
0040 else
0041 /* do something */
0042
0043 /* read min. 1000, max. @bufsize: bytes */
0044 avail = dvb_ringbuffer_avail(rbuf);
0045 if (avail >= 1000)
0046 count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize));
0047 else
0048 /* do something */
0049
0050 2) If there is exactly one reader and one writer, there is no need
0051 to lock read or write operations.
0052 Two or more readers must be locked against each other.
0053 Flushing the buffer counts as a read operation.
0054 Resetting the buffer counts as a read and write operation.
0055 Two or more writers must be locked against each other.
0056
0057 .. kernel-doc:: include/media/dvb_ringbuffer.h
0058
0059 Digital TV VB2 handler
0060 ~~~~~~~~~~~~~~~~~~~~~~
0061
0062 .. kernel-doc:: include/media/dvb_vb2.h
