[ECOS] arm_stub SWI compiler warning

[ECOS] arm_stub SWI compiler warning

[Andrew Lunn]

Hi Mark

arm_stub.c is giving me a compiler warning. The line causing the problem is:

    case 0x3:  // Coprocessor & SWI
        if (((ins & 0x03000000) == 0x03000000) && ins_will_execute(ins)) {
           // SWI
->          return (CYGNUM_HAL_VECTOR_SOFTWARE_INTERRUPT * 4);
        } else {
           return (pc+1);
        }

which is in function 
// Decide the next instruction to be executed for a given instruction
static unsigned long *
target_ins(unsigned long *pc, unsigned long ins)

This code does not look right to me. Shouldn't it be returning the
address in the software interrupt vector, where as its just returning
4x a constant, which is not an address at all.

        Thanks
                Andrew

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[ECOS] Re: arm_stub SWI compiler warning

[Mark Salter]

On Sun, 2004-09-19 at 09:20, Andrew Lunn wrote:
> Hi Mark
> 
> arm_stub.c is giving me a compiler warning. The line causing the problem is:
> 
>     case 0x3:  // Coprocessor & SWI
>         if (((ins & 0x03000000) == 0x03000000) && ins_will_execute(ins)) {
>            // SWI
> ->          return (CYGNUM_HAL_VECTOR_SOFTWARE_INTERRUPT * 4);
>         } else {
>            return (pc+1);
>         }
> 
> which is in function 
> // Decide the next instruction to be executed for a given instruction
> static unsigned long *
> target_ins(unsigned long *pc, unsigned long ins)
> 
> This code does not look right to me. Shouldn't it be returning the
> address in the software interrupt vector, where as its just returning
> 4x a constant, which is not an address at all.
> 
It looks like the code is using CYGNUM_HAL_VECTOR_SOFTWARE_INTERRUPT as
an offset into __exception_handlers and assumes __exception_handlers
is at address 0x0. That will usually work, but it might be better to
use the address contained in the actual vector. 
 
--Mark



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