>I can't read earlier post so I may be missing the point, but is there a=20
>reason
> why you can't just use an array of pointers to functions for this ?
>
> PeterO

An array of pointer to function only really works in a typesafe manner if=20
the signatures of all your functions is the same. You probably want a=20
structure containing pointers to the functions.

(untested code follows!)

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In a header used by both the provider and the consumer of the functions we=
=20
define a structure type that maps the jump table. The elements of this=20
structure are pointers to functions with various signatures.

typedef struct {
    void (*pA)(void);
    int (*pB)(int,int);
} jmptable_t;

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In the provider that defines the functions to be called we create an=20
instance of the jumptable and initialize it (hopefully by the=20
compiler/linker at build time) with pointers to the functions.

void a(void) ;    // prototype the functions first
int b(int,int);      // ...probably in an include file.

<whatever magic it takes to place this next structure at a specified place=
=20
in memory goes here>
jmptable_t jt =3D { a, b };

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
In the consumer that calls the functions:

// Declare a pointer to the jump table and initialize it to the hard addres=
s=20
in the provider:

jmptable_t  *pJT;   =3D (jmptable_t *) 0x12345678;


// Now we can call the functions through the jump table:
           (*(pJT->pA))();              // call the first function
           i =3D (*(pJT->pB))(1,2);    // call the second function

Not sure the '*' belong in the calls above. Probably not. Also one pair of=
=20
parens in each function call are probably unneeded.

-- Bob Ammerman
RAm Systems



--=20
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