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Hi all,
I would like to ask help to some expert in armasm.
In my startup.s file I have the following code which reserves 0x400 bytes of RAM to the stack.
; this is the original startup.s file Stack_Size EQU 0x00000400 AREA STACK, NOINIT, READWRITE, ALIGN=3 Stack_Mem SPACE Stack_Size __initial_sp
Well, I would like to be able to initialise Stack_Size with a value which I have in a cfg.h file or with a const value which I have in a cfg.c file
// this is cfg.h file #define STACK_SIZE 0x00000400
// this is cfg.c file #include "cfg.h" extern const int Stack_Size = STACK_SIZE;
The problem is that I dont know how to export the variable from C and import it into assembly.
I tried to use IMPORT, as in the following, but it does not work.
; this is the modified startup.s IMPORT Stack_Size ;Stack_Size EQU 0x00000400 ; EXPORT Stack_Size AREA STACK, NOINIT, READWRITE, ALIGN=3 Stack_Mem SPACE Stack_Size __initial_sp
Any suggestion?
Thanks in advance, Marco.
You could consider the opposite; i.e., have the define and variable in the startup, export that and then have an extern in your C.
This way is quite straightforward.
Hi,
I already do that. However, it is not just enough to use an extern variable called Stack_Size, but you need to use some more code:
// this is startup.s Stack_Size EQU 0x00000400 EXPORT Stack_Size AREA STACK, NOINIT, READWRITE, ALIGN=3 Stack_Mem SPACE Stack_Size __initial_sp
// this is myfile.c __asm int getstacksize (void) { IMPORT Stack_Size LDR R0,=Stack_Size BX LR }
However, it is not what I want to do.
My aim is to hide the startup.s and use just .h and .c files for configuration.
Thank anyway, marco.