Re: [avr-gcc-list] typdefing 'cost' .. PROGMEM doesn't work

[Dave Hansen]

Joerg Wunsch wrote:
> As Reza Naima <address@hidden> wrote:
>
> >So, would this imply that I found a bug, or am I still missing
> >something?
>
> Yes, you're still missing something.
>
> "const" is /not/ a storage class or something to that avail.  A
> variable qualified with const is just a pretty normal SRAM variable
> anyway.

You need to look at his original example again.  Essentially he had two 
typedefs and two variable declarations analogous to that below:

  typedef const int PW1 PROGMEM;
  typedef int PW2 PROGMEM;

  PW1 v1;
  const PW2 v2;

with v1 being located in RAM and v2 located in flash.  The only difference 
(that I saw) was the movement of the const qualifier from the typedef to the 
variable definition.

Modulo the PROGMEM attribute, these variables should be identical: it 
shouldn't matter where the const appears.  I'm not sure how PROGMEM works 
with typedefs.

FWIW, I avoid putting storage qualifiers (and PROGMEM attributes) on 
typedefs.  They only seem to add confusion.  I would expect both of the 
following variables to reside in flash:

  int const PROGMEM v3;
  int PROGMEM v4;

Regards,
  -=Dave

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