Hi Forum Members:
This should be easy, but I have not figured out the correct syntax to allow my ASM code to use C-defined symbols.
My challenge is to allow SYMBOLS to be defined in C (for convenience) and used in both C and ASM (for ARM) from the single definition. I seem to be having trouble making the ASM code use the #defined value from C.
Accessing C's "my_function" from ASM is no problem, but getting the constant value from C then using it in ASM as a constant value to load into register R0 is the problem I am having.
Any ideas for a solution would be much appreciated:
// ------------- C Code ---------------
#define C_SYMBOL 5 // define C-symbol to have value of 5
void my_function(int parameter_value) // process the given int value
{
switch (parameter_value) // decode given int value
{
C_SYMBOL:
// process my function value when parameter_value = 5
break;
// process other values as necessary
}
}
; --------------- ASM Code (ARM language) ------------
.global my_function ; this should allow ASM to find the C-function called "my_function"
.global C_SYMBOL ; this should allow ASM to get the value of 5 for C_SYMBOL
.text
.arm
start:
; some asm code goes here if necessary
MOV R0, #C_SYMBOL ; prepare value to pass to my_function via R0
BL my_function ; branch and link to my_function passing value in R0
; continue with asm code
.end
I get errors when I try this. Maybe there are some missing "extern" or ".ref .def" directives. The errors are either "undefined" or will not allow #C_SYMBOL to be loaded into R0, I don't recall exactly what because I tried so many things to make this work but without success.
All suggestions appreciated. I will try them tomorrow when I get back to the office.
Thanks,
Garry Anderson.
