How do I get a function to be compiled at address 04 with GPLINK? (For PIC16)

Question

I have a function which is meant to catch all the interrupt calls that will happen, But I cannot get any function to start at address 04.

Note: I dont want to use functions that are specific to interrupt types, I dont want the overhead they produce in the code.

I have tried the following codes with SDCC, maybe not quite related but I will keep them here just in case.

__code __at (4) void handler() {

And

void __at (4) handler() {

With no luck, the manual does not explain any further also.

Answer 1

I know it's a long time after the original question, but I am searching for the same answer and found this helpful info, confirmed working on SDCC 3.3.0: (Source: http://www.mail-archive.com/sdcc-user@lists.sourceforge.net/msg00411.html)

To cause a function to be linked a a fixed, known address, you can surround the function with two other functions: See example below. NOTE: all the _ are double _ _ characters! (You can also define the macros as in the above example, if you intend to use this multiple times throughout your code.

REPLACE #### with your function's desired address below:

test.c

void begin_absolute_code(void) __naked
{
    __asm
          .area ABSCODE (ABS,CODE)
          .org 0x####        // YOUR FUNCTION'S DESIRED ADDRESS HERE.
    __endasm;
}

void your_function(...)
{
     // Do stuff here. This code will be placed at the specified address.
}

void end_absolute_code(void) __naked
{
    __asm
        .area CSEG (REL,CODE)
    __endasm;
}

void other_functions_here(...)
    // These functions will return to relative positions determined by the linker.

Hope this is helpful!