[avr-gcc-list] 8-bit return values again

[Dusan Ferbas]

Hi guys,

when I searched this list for "8-bit return values", I found 2
threads. Described snippets seems to me more about switch/case &
_expression_ optimization:
http://lists.gnu.org/archive/html/avr-gcc-list/2003-06/msg00000.html
http://lists.gnu.org/archive/html/avr-gcc-list/2003-06/msg00005.html

------------------
I want to solve case, when a function is declared as u_char(char, int8,
etc.). It is compiled in a way, that it returns a value in the R24,R25
register pair. This is true not only with literals (see example below),
but also with byte variables. R25 value is never used in a calling code
(see assembler listing below).

Any idea ? Any plans for resolving this ?

> typedef   signed
> char   s_rslt;
...
> s_rslt next_inpIndex(long
> *IndexValue)
> {
>   if (*IndexValue < BIN_NUM_OF_INPUTS)
>   {
>     (*IndexValue)++;
>     return (s_rslt)1;
>   }
>   else
>     return (s_rslt)0;
> }

---

        ldi r24,lo8(1)
        ldi r25,hi8(1)
         ret
.L7:
        ldi r24,lo8(0)
        ldi r25,hi8(0)
         ret

...

        call next_inpIndex
        tst r24                            //No test of R25 in calling code
        brne .+2

Dusan