TI CCS assembly intrinsics format.

sreenivasa upadhyaya

Intellectual 805 points

Hi all,

I am using TI compiler V5.5 in CCS and trying to compile inline assembly code in .c file.

I am using the below format for writing inline assembly intrinsics,

asm("MOV out_val, a, LSL b");

Here out_val, a and b are the c program variables.

I am getting an error " Destination operand Rd must be a register " . This is because its not able to recognize the C variables.

Please suggest me the work around for this and how to use the c variables effectively in asm inline instruction.

Dont know if this query is already posted. Looking for help!! :)

Thansk and Regards,

Sreenivasa U

over 11 years ago

0 George Mock over 11 years ago

TI__Guru**** 253190 points

The TI compiler does not support referring to C variables from within asm() statements.

Thanks and regards,

-George

0 sreenivasa upadhyaya over 11 years ago in reply to George Mock

Intellectual 805 points

Hi George,

Ok. Then whats the solution for the problem, like

int function_x( int a, int b)

{

int c = 0;

asm(" /* assembly statements */ "); // copy the value of b to a

return(c);

}

How can i copy the value of b to a using the intrinsic inline assembly.

Thanks.Looking forward.

Regards,

Sreenivasa U.

0 George Mock over 11 years ago in reply to sreenivasa upadhyaya

TI__Guru**** 253190 points

The TI compiler does not support doing that with asm() statements. Your best alternative is to write a hand-coded assembly routine and call it.

Thanks and regards,

-George

0 sreenivasa upadhyaya over 11 years ago in reply to George Mock

Intellectual 805 points

Hi George,

Thanks for taking time to reply.

Where can i find the guide for writing assembly code for TI compiler CCS v5.5?

I wrote this function and find it doesnt work properly as expected.

I have test.asm file containing

.global add32sat
add32sat
QADD a1,a1,a2 ; // a1 corresponds to r0, a2 corresponds to r1.

I expect this to perform add32 taking care of saturation.

The function add32sat is called from c as follows;

{

int a=1,b=1,c;

c = add32sat(a,b);

}

Please review my above code and suggest the right way!

Thanks.

Regards,

Sreenivasa U.

0 Archaeologist over 11 years ago in reply to sreenivasa upadhyaya

TI__Guru* 84285 points

If it's the QADD instruction you want, you should consider using the TI intrinsic _sadd, like so:

int function_x( int a, int b)
{
    return _sadd(a, b);
}

The TI ARM compiler provides intrinsics for instructions that are difficult to model correctly in C code. See the TI ARM compiler user's guide for the list.

http://processors.wiki.ti.com/index.php/TI_Compiler_Information#Compiler_Manuals

0 sreenivasa upadhyaya over 11 years ago in reply to Archaeologist

Intellectual 805 points

Hi,

I have been facing some new issues with assembly programming.

1. I have an instruction like

"MOV r0,#0x7FFFFFFF " in my .asm file.

I get a compilation error saying

" Invalid Immediate operand".

While MOV r0,#0x80000000 does not give compilation error.

Regards,

Sreenivasa

0 Archaeologist over 11 years ago in reply to sreenivasa upadhyaya

TI__Guru* 84285 points

ARM does not have a MOV instruction which can take a constant of that size. It does have a MOV instruction which can take an 8-bit immediate value shifted by an arbitrary amount; the constant 0x80000000 qualifies for that instruction.

Try using the MVN instruction instead:

MVN r0,#0x80000000

0 sreenivasa upadhyaya over 11 years ago in reply to Archaeologist

Intellectual 805 points

Hi, I understand. Any document mentioning this ? Also if the instruction i want to achieve is MOV R0,#7fffffff what could i use ?? Is it MVN R0,#7FFFFFFF?? Thanks and regards, Sreenivasa

0 Archaeologist over 11 years ago in reply to sreenivasa upadhyaya

TI__Guru* 84285 points

You should write it exactly like this:

MVN R0,#0x80000000

Please read the documentation (the ARM Architecture Reference Manual for the ARM architecture you are using) for what the MVN instruction does. You should consult the Architecture Reference Manual for descriptions of all of the ARM instructions.

0 sreenivasa upadhyaya over 11 years ago in reply to Archaeologist

Intellectual 805 points

Hi Archaeologist,

Thanks a lot. Things are clear now.

Regards,

Sreenivasa U

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TI CCS assembly intrinsics format.