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c_audio channel connected to the audio() thread

c_clk_ctl channel connected to Endpoint0() for conﬁguration of the clock

c_clk_int channel connected to the decouple() thread for clock interrupts

void SpdifReceive(in buffered port:4 p,

streaming chanend c,

int initial_divider,

clock clk)

S/PDIF receive function.

This function needs 1 thread and no memory other than ~2800 bytes of program

code. It can do 11025, 12000, 22050, 24000, 44100, 48000, 88200, 96000, and

192000 Hz. When the decoder encounters a long series of zeros it will lower the

divider; when it encounters a short series of 0-1 transitions it will increase the

divider.

Output: the received 24-bit sample values are output as a word on the streaming

channel end. Each value is shifted up by 4-bits with the bottom four bits being

one of FRAME_X, FRAME_Y, or FRAME_Z. The bottom four bits should be removed

whereupon the sample value should be sign extended.

The function does not return unless compiled with TEST deﬁned in which case it

returns any time that it loses synchronisation.

This function has the following parameters:

S/PDIF input port. This port must be 4-bit buﬀered, declared as

in buffered port:4

c channel to output samples to

initial_divider

initial divide for initial estimate of sample rate For a 100Mhz

reference clock, use an initial divider of 1 for 192000, 2 for

96000/88200, and 4 for 48000/44100.

clk clock block sourced from the 100 MHz reference clock.

void adatReceiver48000(buffered in port:32 p, chanend oChan)

ADAT Receive Thread (48kHz sample rate).

The function will return if it cannot lock onto a 44,100/48,000 Hz signal. Normally

the 48000 function is called in a while(1) loop. If both 44,100 and 48,000 need to

be supported, they should be called in sequence in a while(1) loop. Note that the

functions are large, and that 44,100 should not be called if it does not need to be

supported.

This function has the following parameters:

REV 6.1

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