topic S12X CW4.5 function pointers in CodeWarrior for MCU

S12X CW4.5 function pointers

gravity — Thu, 11 May 2006 09:35:41 GMT

Hi,

S12XDP512, CW 4.5, LARGE memory model

I have a function pointer defined as

typedef void (*function)(void);

I have a void pointer which is holding the function address 0x7DB089'G ( which is actually laid out in memory as B0897D.

When I attempt to cast it (or call it) the runtime GLOBAL_TO_LOCAL function is called. The result is

0x7DC289 (or C2897D as laid out in memory). This is incorrect and crashes the code.

Any suggestions how I can get around this. I'm guessing that the routine assumes this is a data pointer and not a function pointer?

Cheers

Re: S12X CW4.5 function pointers

Alban — Thu, 11 May 2006 17:26:01 GMT

Hi Gravity,

When you use external address space, you need to use FAR pointers to indicate to the debugger which space you address and avoid address to be truncated or wrong.

See Nabla's post and the code I had on the NE64 with extended bus.

If I understood well what you meant...
Alban.

Re: S12X CW4.5 function pointers

gravity — Fri, 12 May 2006 09:02:03 GMT

I compiling using large memory model, so I thought everything is a far pointer?

Re: S12X CW4.5 function pointers

Alban — Fri, 12 May 2006 14:43:30 GMT

Sorry, but I can't confirm...

Re: S12X CW4.5 function pointers

gravity — Sat, 13 May 2006 08:39:24 GMT

I think my problem is S12X specific and is to do with translating from a Global address to a local address.

The global address is 0x7DB089'G but the local address becomes 0xF6C289'L

Re: S12X CW4.5 function pointers

CrasyCat — Mon, 15 May 2006 17:57:36 GMT

Hello

Which CPU are you currently using (HCS12XDP512, ....)?

From what I can see (from HCS12X reference manual), address 0x7DB089'G is in fact equivalent to address 0xF6B089'L.

All absolute addresses you specify in ANSI C source code are considered as logical (even in large memory model).

So instead of writing

typedef void (*function)(void);
function func;

func = (function) 0x7DB089;

func();

You have to write

typedef void (*function)(void);
function func;

func = (function) 0xF6B089;

func();

CrasyCat

Re: S12X CW4.5 function pointers

gravity — Tue, 16 May 2006 05:26:18 GMT

Hi,

S12XDP512.

The problem was that I was passing the function pointer around using a "void*". I had made this "void*" a "void* far", so it was casting it to global addressing.

Cheers

Re: S12X CW4.5 function pointers

CrasyCat — Tue, 16 May 2006 15:30:05 GMT

Hello

Is the problem fixed now?
If not, can you send me a code snippet reproducing the trouble.

CrasyCat