the compiler is complaining because you have an extra or a missing "const" in your structure definitions. There is a mismatch between your flash declaration and the type of pointer within your struct. Probably adding a const keyword to the pointer within your struct and removing the const in your declaration will fix the problems.
-----Original Message----- From: avr-gcc-list-bounces+larry=barello....@nongnu.org [mailto:avr-gcc-list-bounces+larry=barello....@nongnu.org] On Behalf Of Vincent Trouilliez Sent: Thursday, January 22, 2009 8:20 AM To: avr-gcc-list@nongnu.org Subject: [avr-gcc-list] A couple GCC warnings I would like to understand / get rid of... Hi, I am having a couple GCC warning I would like to understand and hopefully clear with a graceful modification of my code, if anyone can help... Basically it's to do with the structures I put in Flash, and the pointers to these structures (which are themselves located in said structures). When I initialize the structure with constant data, GCC coughs about the field where I store the pointer. Then later in the code, when trying to retrieve/read that pointer and use it, I also get a warning. It has to be said that GCC actually understands what I want to do, because it stored and retrieved the correct pointer value, and my program works as expected. It's just that these warning are annoying and of course, maybe I did do a mistake in the syntax, and that would be the opportunity to learn a little something new today.. #1 warning: when storing pointer in Flash ------------------------------------------ Pointer is stored in structure "menu_main", and points to "menu_sub" (structure of the same type). //target structure const struct TMenu menu_sub PROGMEM = { .... }; //struct holding the pointer const struct TMenu menu_main PROGMEM = { ... {.... , &menu_sub,...}, <-------WARNING } }; The warning is: "warning: initialization from incompatible pointer type" I don't understand why it's incompatible. I the structure is define as this: struct TMenu; struct TMenuItem { char text[20]; struct Tmenu *ptr; void (*fptr)(); }; the pointer ptr is declared as a pointer to a structure of type TMenu, and of course I initialize it with the address of such a structure (&menu_sub), so... where is the incompatibility ? :-/ #2 warning: when retrieving/reading pointer from Flash ------------------------------------------------------ //---------------------------------- // declare pointers of same type as found in struture, // in order to read them from flash void (*FncPtr)(); const struct TMenu *SubPtr; FncPtr = pgm_read_word( & (p->items[cursor].fptr) ); SubPtr = pgm_read_word( & (p->items[cursor].ptr) ); //------------------------------------- I get a identical warning for each of these lines/reads : "warning: assignment makes pointer from integer without a cast" Here for a change, I think I can, agree with GCC, since pgm_read_word returns an integer, but what's the syntax to turns that back into the pointer it once was ?! Something like that ? FncPtr = ( void (*FncPtr)() )pgm_read_word( & (p->items[cursor].fptr) ); and similarly: SubPtr = (*SubPtr)pgm_read_word( & (p->items[cursor].ptr) ); Tried, doesn't work... A cyber beer offered to anyone with the answer :-) Regards, -- Vince, still at the very bottom of the learning curve, brrr... _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
