Hello!
I have uVision that compiles fine with the C51 v7.03 compiler and the related package, but not complete with the 8.06. I used two different Keil installations. All files are in the same folder.
In the 8.06 I get linker errors like "object does not fit in to pdata page" and "0080H". This looks like the compiler was thinking the PDATA was only 128 bytes, but it is set to 256 bytes in the startup.a51. Any clue what's different in the newer Keil package?
Also there is a warning in 8.06 (which does not show in 7.03) "converting non-pointer to pointer" on this
ptr_xdata = sPtr_obj->Adresse;
while the vars are set like this:
uchar uc_set_obj( uchar pdata *ptr_Set) { uchar i; uchar xdata *ptr_xdata; struct stOBJADR code *sPtr_obj; sPtr_obj=&Obj[*ptr_Set]; . . . ptr_xdata = sPtr_obj->Adresse; }
The struct stOBJADR has a member "uint Adresse;"
I can see no wrong use of the pointers. I just want to be sure that the warning does not affect the code to not work correctly.
Afaik, a pointer points to a value, but it doesn't have one.<p>
Well, I'm afraid your knowledge is wrong, then.
A pointer, like any other variable, has an address (where it is stored), and a value (which can be used to access a certain location in memory). A pointer does not need to point to a value.
Example:
void * some_void_ptr
some_void_ptr is a pointer. At least as far as the compiler is concerned, it does not point to a value. Hence, the compiler cannot, for example, increment it:
some_void_ptr++;
will result in an error. It also cannot dereference it:
*some_void_ptr = 0;
will also result in an error.
However, you can take the address of this pointer, for example:
void ** some_ptr_to_void_ptr; some_ptr_to_void_ptr = &some_voidptr;
This is C, so I don't care about memory addresses.
C is still way too close to the actual hardware to ignore the target platform. The C compiler will not save you from alignment faults and access penalties that stem from "not caring about memory addresses".