Set function to specific address in PIC18F with the HI-TECH C compiler

Question

I want to put a function in an specific address of memory like PIC C Compiler (#org). I'm using MPLAB X, HI-TECH compiler and PIC18F4550.

In PIC C compiler:

#org 0x1000, 0x2000
void MyFunction()
{
}

//In other part of code I'll use: asm("goto 0x1000");

How to do this in MPLAB X with the HI-TECH compiler?

I don't understand why you'd need to. You can reference the symbol MyFunction from assembly (maybe as _MyFunction depending on compiler). — Majenko, Oct 29, 2014 at 14:29
Also, you should never ever ever "goto" a function, or "goto" anywhere outside your current function. — Majenko, Oct 29, 2014 at 14:31

m.Alin · Accepted Answer · 2014-10-31 07:15:33Z

1

IIRC, you can set a function to an absolute address by using the "@" qualifier:

void MyFunction() @ 0x2A0
{
    ...
}

So the function MyFunction will be placed at address 0x2A0 in Program Memory.

answered Oct 29, 2014 at 14:50

m.Alin

10.4k19 gold badges58 silver badges87 bronze badges

\$\begingroup\$ Thanks @m.Alin, I worked. I'd like to ask you how to use int address = 0x20; **asm("goto "___mktstr(addr));** but If I use asm("goto "___mktstr(0x20)); works. I want to use goto to go a specific address using addr variable, perhaps there is another option like goto_address(addr) in pic CCS compiler. Thank you. \$\endgroup\$
– 788498
Oct 30, 2014 at 6:34
\$\begingroup\$ The ___mktstr(x) macro stringifies its argument. ___mktstr(0x20) will return the string "0x20", but ___mktstr(addr) will return the string "addr". \$\endgroup\$
– m.Alin
Oct 30, 2014 at 7:22
\$\begingroup\$ Thanks, but I still couldn't find a way to GO to a variable address. It looks like asm() argument must be char constant. Is there another solution to jump to an address using goto? \$\endgroup\$
– 788498
Oct 31, 2014 at 4:56
\$\begingroup\$ @jaspher I'm not experienced in assembly. You should ask a new question regarding that. \$\endgroup\$
– m.Alin
Oct 31, 2014 at 7:14

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Richard Williams · Accepted Answer · 2014-10-30 00:28:17Z

-1

use the linker command file to set the address of .text portion of MyFunction

answered Oct 30, 2014 at 0:28

Richard Williams

291 bronze badge

2

\$\begingroup\$ This doesn't seem to answer the question. Please add further explanation. \$\endgroup\$
– Null
Oct 30, 2014 at 0:47

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2 Answers 2