[hatari-devel] [Crossbar emulation] : new infos, + some help needed

[Laurent Sallafranque]

Hello,

DMA part is still a bit confuzing.
I'll try to include ADC to crossbar first, then, link ADC to DSP and DAC.

At the end, I'll connect the DMAs.
Like this, I'll have working examples to use as tests.

> Sorry, I lost a little bit track about all your other mails... Do your
> problem still persist here, or is this fixed already?

I've solved some of them. some are remaining. But I'll continue to 
explore all of this during the next weeks. I need to understand it 
better to code it well :)

> I saw that you're using a DACBUFFER_SIZE of MIXBUFFER_SIZE*2*64*2 Bytes
> there, ... but that's a buffer of 4 Megabytes! Isn't that a little bit
> too much for a sound buffer? It doesn't sound right to me to use such
> big buffers for sound...

Yes it is !
I see that you used a Sound_Update() function in STe DMA.
I'll try to do the same to reduce the Sound buffer.

Regards

Laurent



Thomas Huth a écrit :
>  Hi Laurent,
>
> sorry for the late reply, I'm quite busy with real life work atm...
> (and as it currently looks like, this won't change in the upcoming
> weeks...)
>
> On Wed, 23 Sep 2009 16:23:32 +0200
> Laurent Sallafranque <laurent.sallafranque at free.fr> wrote:
>
>   
>> Yes, it seems that there are 2 sets of DMA devices in the Falcon (one 
>> for sound and one into the crossbar).
>>     
>
> You mean one for playing (memory to crossbar) and one for recording
> (crossbar to memory), don't you?
>
>   
>> My first problem was to understand which parameters are for each DMA,
>> as in the compendium, they're both names "DMA".
>> (In page B-28 of the compendium, you can read : (DMA OUT) is linked
>> to (DMA IN) for example).
>>     
>
> Well, I guess DMA OUT = DMA playing and DMA IN = DMA recording ?
>
>   
>> For the DAC part :
>>
>> I've taken the DAC code from DmaSound.c
>> I've seen that DAC merges it's datas in a buffer coming from the PSG.
>>
>> I think that my frequency problem comes from this function, but I'm
>> not sure.
>> Thomas, Would you please have a look at Crossbar_GenerateSamples() ?
>> Can I use it the same as you did in DmaSound.c ?
>> (You were reading the whole buffer at one time, I'm sending datas in 
>> interrupted mode (at a certain frequency).
>>     
>
> Sorry, I lost a little bit track about all your other mails... Do your
> problem still persist here, or is this fixed already?
>
> I saw that you're using a DACBUFFER_SIZE of MIXBUFFER_SIZE*2*64*2 Bytes
> there, ... but that's a buffer of 4 Megabytes! Isn't that a little bit
> too much for a sound buffer? It doesn't sound right to me to use such
> big buffers for sound...
>
>  Thomas
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