[sdiy] was how_you_got_started...

[Scott Gravenhorst]

Thomas Strathmann <thomas at pdp7.org> wrote:
 >On 26/09/15 04:31, Scott Gravenhorst wrote:
 >> Yes, I found this to be true by doing it.  I've been able to write a
 >> nice additive flute model monosynth for dsPIC33F in C, but my best
 >> efforts at polysynths are in assembly language.  The main issue for
 >> me is the fact that there is no native data type support for 16 bit
 >> fixed point arithmetic.  Worse yet is that sometimes designs need
 >> more than one definition for 16 bit fixed point.  Usually 1.15
 >> works, but there are times other configurations are necessary.  This
 >> is rather difficult
 >> and at least ugly in C even using typedef etc.  Just ugly.  And in C
 >> I had to write several functions in assembly language anyway that
 >> handle the use of DSP instructions because they are not used by the
 >> C compiler even if it's logical to do so.  At least in my
 >> experience...  can anyone tell me how to make an FIR filter in C30 
 >> that uses the MAC instruction... ??
 >
 >What about using C++ for such cases. Seems like a good fit for hiding
 >the complexity of custom arithmetic code. Probably not ideal, but 
 >surely better than writing raw assembly code all the way.
 >
 >	Thomas

Well, C++ may be able to handle the fixed point problem better than C, 
but it still won't use the MAC or other DSP instructions.

But for me, using assembly language with the dsPIC is not a burden at 
all and it allows me to use binary "tricks" that aren't obvious or even 
possible in C without yet more ugly code.  I've done assembly language 
programming for so long, it's really (as someone else posted) just like 
writing a letter because I can think at that level after doing it for so 
many years.  I've always been able to write much tighter code in 
assembly language than in C (and I've used C for more than 30 years).

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22