Memory Mapping

[ritchie]

Hello,

Question on memory mapping?

I have a structure for PortA... say,

struct {
unsigned int A0:1;
unsigned int A1:1;
...
unsigned int A7:1;
} PortABits;
#locate PortABits=0xF80

With this structure you can now set/reset bit specific ex. PortABits.A0 = 0.

My convern really is that? Is their another way of doing this without using #locate but still you can use the instruction PortABits.A0 = 0?

Need your comments and information.

Thanx

[Haplo]

One other way:

#bit A0 = 0xF80.0

Then you can use A0=0.

[Mark]

No matter how you do it, you still have to tell the compiler what register portA is.

[Trampas]

ritchie,

Is your concern the portablitly of the code?

Since the CCS compiler does not have a linker, their is no other way to locate the variable other than the #locate.

What you can do is set up a #if statement which detects which compiler you are using and then place all the locate statements in there. This way your code can still compile and run on multiple compilers.

Trampas

[ritchie]

Yah my concern really is the portability of the code for other PIC compilers coz the #locate and #bit are CCS specific built-in preprocessors.

Similarly the CCS #byte preprocessor-- I never use this coz I have my own definition which is similar to a #byte and it goes this way:

[Mark]

Put the declarations in a header file. For the C18 compiler, "I" do not have to specify the locations. Switching between the two compilers, I just include a different processor header file.

[Haplo]

Stay away from #byte and #bit. Use statements like input(PIN_A0) or output_low(PIN_A0). Any other compilers you may want to migrate to later will definitely have similar funtions and changing the code will not be that difficult.