-pic | CS+ V7.00.00

-pic

[Format]

-pic

[Default]

This option does not generate code with the program section as PIC (position independent code).

[Description]

-	This option generates code with the program section as PIC (position independent code).

-	In PIC, all function calls are performed with BSR or BRA instructions. When acquiring the address of a function, a relative address from the PC should be used. This allows PIC to be located at a desired address after linkage.

[Example]

-	Calling a function (only for branch=32)

void func()

        sub();

[Without -pic]

_func:

            MOV.L       #_sub,R14

            JMP         R14

[With -pic]

_func:

            MOV.L       #_sub-L11,R14

L11:

            BRA         R14

-	Acquiring a function address

void func1(void);

void (*f_ptr)(void);

void func2(void)

        f_ptr = func1;

[Without -pic]

_func2:

            MOV.L       #_f_ptr,R4

            MOV.L       #_func1,[R4]

RTS

[With -pic]

_func2:

         MOV.L       #_f_ptr,R4

L11:

         MVFC        PC,R14

         ADD         #_func1-L11,R14

         MOV.L       R14,[R4]

RTS

[Remarks]

-	In C++ or EC++ compilation, the pic option cannot be selected. If selected, message W0511171 is output as a warning and the selection of the pic option is disabled.

-	The address of a function which is PIC should not be used in the initialization expression used for static initialization. If used, error E0523026 will occur.

-	<Example of using a PIC address for static initialization>

void pic_func1(void), pic_func2(int), pic_func3(int); /* Becomes PIC */

void (*fptr1_for_pic) = pic_func1; /* Uses PIC address in static initialization: Error */

struct PIC_funcs{ int code; void (*fptr)(int); };

struct PIC_funcs pic_funcs[] = {

    { 2, pic_func2 },              /* Uses PIC address in static initialization: Error */

    { 3, pic_func3 },              /* Uses PIC address in static initialization: Error */

};

-	When creating a code for startup of the application program using the PIC function, refer to the Application Startup section of the STARTUP chapter.

-	For the PIC function, also refer to the Usage of PIC/PID Function of the STARTUP section.