[Sdcc-user] SDCC should not otimize!

[<wei...@t-...>]

Hi

i'm again. There is a little problem i have here. I have the following
C-Code:

  dummy = graRD1;      //Dummy Read
  grafik_wbusy();
  dummy = graRD1;
  grafik_wbusy();

graRD1 is a XRAM location declared as:

volatile xdata at 0xF003 unsigned char graRD1;

Now the asm file look's like the optimizer only use:

  dummy = graRD1;
  grafik_wbusy();

one time. The second read is optimized. I understand why this is so but i
have to do a dummy read before the normal read. The compiler always otimize
the second read away. I can define a variable and do something with it.

  temp = graRD1;      //Dummy Read
  grafik_wbusy();
  dummy = graRD1;
  grafik_wbusy();

/*do something with dummy*/

dummy = dummy | temp;

But this can't be the right way to do that. Is there a statement or
something to tell the compiler not to otimize these four lines?

Please excuse (<- Hope this is "entschuldigt") my bad English.


Matthias Weißer

Wer einen Rechtschreibfehler findet darf ihn behalten

http://www.matwei.de/
mat...@ma...