topic Re: Assembly problem with indirect X instructions in CodeWarrior for MCU

Assembly problem with indirect X instructions

Jim_P — Thu, 30 Jun 2011 02:31:56 GMT

I am having to do a bit of Assembly coding - - for some 64 bit math - - simple add and subtract.

as I have started coding this I checked what I was doing and getting a series of error messages.

windows 7 64 bit CW10.1 HS08JM project

this is inside of a function

union DLong Add64( union DLong A, union DLong B )
    {
    static union DLong a, b, C;
    static byte D,E,F;
    byte I;
    I = 7;
    a = A;
    b = B;

    asm
        {

        LDA D;
        ADD E;
        STA F;
        LDX #7
        LDA D,x;
        ADD E, x;
        STA F, X;
        ............. more to be added
        }

    return ( C );
    }

error message occurs on the lines that I am trying to index using the X register.

i.e. LDA opcode16,X

I get the error message on the indexed opcodes of

C18123 End of Line expected

for each of the index X assembly codes

I have used inline assembly before without problems - - first time using indexed addressing

thanks Jim P

Re: Assembly problem with indirect X instructions

bigmac — Thu, 30 Jun 2011 10:19:28 GMT

Hello JP,

While it may not be the cause of your error messages, your inline code does not appear to make sense unless the variables D, E, and F are declared as arrays of at least eight elements. You cannot assume a particular order in which the static variables are linked to memory.

I think that there may also be a problem with the assignments a = A; and b = B; since these are unions, and you do not specify a particular element of the union.

Regards,

Mac

Re: Assembly problem with indirect X instructions

kef — Thu, 30 Jun 2011 11:53:04 GMT

Jim, I think you need to use address operator @ here:

        LDA @D,x;
        ADD @E, x;
        STA @F, X;

Re: Assembly problem with indirect X instructions

Jim_P — Fri, 01 Jul 2011 03:58:31 GMT

you are looking at lots of test code trying to figure out what I am getting these errors.

and a union to union assignment is just fine - - - - As A = B

note the actual code is simply a block transfer. If assigning an int or something to a union it needs to know

what it is it is being assigned to - - - -

Re: Assembly problem with indirect X instructions

Jim_P — Fri, 01 Jul 2011 04:01:37 GMT

Thanks that makes sense - - - - nothing else seemed to

I figured out a work around - - - I assigned the variables to a fixed address and then hard coded that address

worked but now what I would call ideal or right.

the use of the @ seems to be the key, I did try the & and that did not work.

think that part of my problem is that the variable is on the stack - - when passed. So no fixed address.

even making the variables static did not seem to help as that should have created a fixed address for the variables

Thanks

Re: Assembly problem with indirect X instructions

bigmac — Fri, 01 Jul 2011 16:35:28 GMT

Hello JP,

While the attached code probably does not do what you require, it does demonstrate a method of setting up a stack frame for arithmetic operations, and makes use of inline assembly code. Maybe you will be able to extract some ideas.

Regards,

Mac

Re: Assembly problem with indirect X instructions

Jim_P — Wed, 06 Jul 2011 08:14:19 GMT

Thanks - I will keep the code for reference and use if the need arrives

Jim P