[sdiy] audio microprocessors and C++

jays at aracnet.com jays at aracnet.com
Thu Mar 6 01:35:31 CET 2008


Julian,

I personally don't think it is hard or impossible. But then I'm an engineer that works in embedded software. So I got both the software and hardware chops.

To me here are the issues.

1) When doing something that needs to be portable create an abstraction layer between the software and a hardware. This is a piece of sw that has a common interface to your application and an interface to what ever the target drivers are. It's purpose is to isolate the hardware with a small amount of software. Need to port to a new platform then create a new abstraction layer verses modifing the application.

2) Endian issues. This is the byte ordering of multi-byte data. If you have a closed system then you do not have to worry about this. But if you are taking data from an external source this may or may not be a problem. An example is a 16 bit audio sample from an external source maybe low byte, high byte. Your hardware and compiler may work in high byte, low byte. So some swizziling (sp?) may need to be done.

3) Code size. C++ code will not be as small as C code. A really good C compiler can approch code size of assembly language. So a processor that can handle a lot of memory is good.

4) Tools. Some processors have good tool support from the GNU folks. Others can cost a lot of money.

I've just got started working on an embedded audio thing. Decided to go with an ARM LPC2468 chip using a system from Embedded Artists as a prototype to do proof of concept. They have an uClinux kernal up and running for it. The chip has an 16 bit I2S interface built into the hardware which is what I need.

Hope this provides some insight.
Jay S.


Julian wrote:

> Forgive me, as ive done very little external research on this before asking here...
> 
> I was chatting to someone last night about audio processing, and it got onto microprocessors as a solution for 'wierd' stuff...
> 
> I have a friend whose a professional C++ programmer, and has, for his own fun, written several little 'windows' applications doing 
> things like genetic granular stuff.
> 
> This would all have been using the standard windows, whatever their called, drivers? dlls? - ie not writing to the hardware direct, 
> but to a sofware 'middle man'
> 
> Anyway, im starting to digress..
> 
> I was wondering as to how feasible it would be to convert this into hardware?  What i should be reading, and what i should be asking 
> him (i have little experinace with C++ and he has little experiance of electronics)
> 
> Any pointers?
> 
> Thanks, Julian 
> 
> 
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