1Digital TV Common functions 2--------------------------- 3 4Math functions 5~~~~~~~~~~~~~~ 6 7Provide some commonly-used math functions, usually required in order to 8estimate signal strength and signal to noise measurements in dB. 9 10.. kernel-doc:: include/media/dvb_math.h 11 12 13DVB devices 14~~~~~~~~~~~ 15 16Those functions are responsible for handling the DVB device nodes. 17 18.. kernel-doc:: include/media/dvbdev.h 19 20Digital TV Ring buffer 21~~~~~~~~~~~~~~~~~~~~~~ 22 23Those routines implement ring buffers used to handle digital TV data and 24copy it from/to userspace. 25 26.. note:: 27 28 1) For performance reasons read and write routines don't check buffer sizes 29 and/or number of bytes free/available. This has to be done before these 30 routines are called. For example: 31 32 .. code-block:: c 33 34 /* write @buflen: bytes */ 35 free = dvb_ringbuffer_free(rbuf); 36 if (free >= buflen) 37 count = dvb_ringbuffer_write(rbuf, buffer, buflen); 38 else 39 /* do something */ 40 41 /* read min. 1000, max. @bufsize: bytes */ 42 avail = dvb_ringbuffer_avail(rbuf); 43 if (avail >= 1000) 44 count = dvb_ringbuffer_read(rbuf, buffer, min(avail, bufsize)); 45 else 46 /* do something */ 47 48 2) If there is exactly one reader and one writer, there is no need 49 to lock read or write operations. 50 Two or more readers must be locked against each other. 51 Flushing the buffer counts as a read operation. 52 Resetting the buffer counts as a read and write operation. 53 Two or more writers must be locked against each other. 54 55.. kernel-doc:: include/media/dvb_ringbuffer.h 56 57Digital TV VB2 handler 58~~~~~~~~~~~~~~~~~~~~~~ 59 60.. kernel-doc:: include/media/dvb_vb2.h 61