[hatari-devel] Falcon sound

Laurent Sallafranque laurent.sallafranque at free.fr
Sat Feb 20 10:06:13 CET 2010


Hello,

I send you a little checkpoint about crossbar code.

I've nearly finished to write the crossbar sound emulation now.

I've removed all the double variables.
I've added the sound control independently for left and right channels 
for ADC and DAC.

Sound is OK in DMA mode and in ADC -> DAC direct transfers.
It is still noisy when sound comes from DSP.

I've done a little test in Crossbar_SendDataToDAC function.
I've changed :

        dac.buffer_left[dac.writePosition] = value;
        dac.buffer_right[dac.writePosition] = value;

by

        dac.buffer_left[dac.writePosition] = 15000;
        dac.buffer_right[dac.writePosition] = -15000;

I've recorded the output sound and looked at it under audiocity.
The curve is a perfect line without any hole in it.

With real sound (restore value variable) from DSP, there are holes in 
the curve (value = 0) here and there.
(It seems that the 0 values arrives at a constant frequency).

I'll try to correct this problem.

There's another problem that need a correction in crossbar --> SSI 
transfers.
Crossbar transfer can be configured at 8 bits and DSP one at 16 bits.
This case is not handled yet.

 From me, it's the 2 last problems to correct in the crossbar.
If you have encountered some more problems with crossbar that I haven't 
found, don't hesitate to tell me.

Regards

Laurent




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