To solve the far function pointer issue I have developed a set of macros
shown below:
/*
* far.h by Robert Kavaler 1/31/2010
*
* The MSPGCC MSP430X compiler currently does not handle pointers to
functions
* correctly. The compiler treats all pointers as 16 bits, but pointers
* to functions should be 20 bits. As a workaround to handle pointers to
* functions, a set of wrapper macros was developed.
* The macro _FAR is merely shorthand for the far attribute.
* The macro _FARDEF(t, x, p) creates a wrapper function
* x_inlowmem for the function x. It also acts as the formal declaration of
* the actual function. t is the type and p a list of parameter for
* the C declaration of the wrapper function. The wrapper function itself
* is merely a branch to the actual function. The wrapper function always
* lives in the lower 64K address space so it can be accessed/referenced
with
* a 16 bit pointer.
* The macro _FARREF(x) is used to reference the wrapped
* function in C. It is basically the 16 bit address reference of the
* branch instruction that branches to the 20 bit function x.
* The macro _FARDEFH(t, x, p) creates a definition for
* both the far function and the wrapper function for use in header files.
* Example:
* _FARDEFH(void, complicatedStuff, (char *s, int *y));
* _FARDEF(void, complicatedStuff, (char *s, int *y)) { function code }
* void (*func)(char *, int *y) = _FARREF(complicatedStuff);
*/
#ifdef MSP430X5
#define _FAR __attribute__ ((far))
#define _FARREF(x) x ## _inlowmem
#define _FARDEF(t, x, p) t x ## _inlowmem p; \
asm(" .text\n" #x "_inlowmem: bra #"
#x\
"\n\t.section\t.fartext,\"ax\",@progbit\
s");\
_FAR t x p
#define _FARDEFH(t, x, p) _FAR t x p; t x ## _inlowmem p
#else
#define _FAR
#define _FARREF(x) x
#define _FARDEF(t, x, p) t x p
#define _FARDEFH(t, x, p) t x p
#endif
--
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