I'm having one of my major off days!

I'm trying to invert the contents of an array, and am going all over 
the place to achieve  what I think should be only a couple of lines of 
'c' code.

I have a constant array containing font pixel data for a graphics LCD.

I access it by,

BYTE *fnt;
   
   fnt = GLCD_font_set(ch);

No problems here.

However this does not work

*fnt = *fnt ^ 0xFF; '' take contents of fnt and invert, place back in 
fnt.

Nor does bracketing fnt's,  contents do not alter.

This does work in my 'c' compiler

if (colour == WHITE)
    {
        tmp = *fnt; 
        tmp = tmp ^ 0xFF; //invert font code
        fnt = (unsigned char *)tmp;
     }

The above code has a build failure if I use Microchip C30, that is 
happy with

if (colour == WHITE)
{
    fnt = font[1];//test purposes, only get one 8 pixel strip from 
font table
    tmp =  fnt ;
   tmp = tmp ^ 0xFF;
   fnt = tmp;   
}

I don't see why the neater first attempt isn't working.

tracing the assembler with the FED-C compiler is not the easiest of 
task, due to compiler macro overheads all over the place.

Colin
--
cdb,  on 9/26/2009






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