Small Device C Compiler suite

On Tue, 20 May 2003, Greg Hill wrote:

> I'm trying to get some inline assembly into a C file (it's a semi-precise
> time delay loop). Here's my sdcc version:
> SDCC : mcs51/gbz80/z80/avr/ds390/pic14/pic16/TININative/xa51/ds400 2.3.5
> (May 18 2003) (UNIX)
> 
> It seems that the '$' character I've used in my label in the inline asm is
> confusing the peephole optimizer. (I used the numeric label with $ at the
> end because it's suggested in the current sdccman.pdf). Here's the output
> I get:
> gregh: ~/projects> sdcc -mpic14 -pp16f628 second.c
> Processor: p16f628
> Error while parsing peep rules (check peeph.def)
> Line:       goto 00001$
> Token: '$'
> 
> and here's the code for the function with the inline asm:
> void delay500us(unsigned char count) {
>   for(; count > 0; count--) {
>     _asm
>       movlw  0xA6
>       movwf  _delay
> 00001$:
>       decfsz _delay,f
>       goto   00001$
>       _endasm;
>   }
> }

What happens if you do this:

     _asm
      movlw  0xA6
      movwf  _delay
 L1:  decfsz _delay,f
      goto   L1
     _endasm;


The "assembler" for the inline assembly is a really simple 1-line 
assembler. The label must occur on the same line of the instruction to 
which it refers. The '$' is not a supported character. In fact in gpasm, 
'$' is the "current address" operator. E.g. one can write goto $+2 to 
branch 2 instructions beyond the address at which the goto is located.

Scott

On Tue, 20 May 2003, Scott Dattalo wrote:

> What happens if you do this:
>
>      _asm
>       movlw  0xA6
>       movwf  _delay
>  L1:  decfsz _delay,f
>       goto   L1
>      _endasm;
>

I get:
Processor: p16f628
        GOTO    L1
ERROR: LinkFlow, branch instruction doesn't have label
 *** Saved 1 registers ***
No registers saved on this pass
        GOTO    L1
ERROR: LinkFlow, branch instruction doesn't have label
 *** Saved 1 registers ***
No registers saved on this pass
second.asm:414:Error [113] Symbol not previously defined (L1).

In the .p output file, I see that the L1 label got eaten somewhere along
the chain, before assembly:

<cut all but _asm.._endasm; block>
;#CSRC  second.c 116
;  _endasm;
        MOVLW   0xa6
        MOVWF   _delay
        DECFSZ  _delay,F
        GOTO    L1

Of all the combinations I've tried, I haven't found a way to make the
label get included in the output file.

Greg

On Tue, 20 May 2003, Greg Hill wrote:

> On Tue, 20 May 2003, Scott Dattalo wrote:
> 
> > What happens if you do this:
> >
> >      _asm
> >       movlw  0xA6
> >       movwf  _delay
> >  L1:  decfsz _delay,f
> >       goto   L1
> >      _endasm;
> >
> 
> I get:
> Processor: p16f628
>         GOTO    L1
> ERROR: LinkFlow, branch instruction doesn't have label

Damn. I was afraid of that. This is clearly a bug that I need to fix.  
Meanwhile, I'm afraid the only solution is to hand edit the SDCC generated
assembly.

Scott