Re: [avr-gcc-list] Trying to learn Interrupts

[Dmitry K.]

Laszlo wrote:
> ----------------
> ext_int_0:
>     in r16,TCNT1H
>     st X+,r16
>     in r16,TCNT1L
>     st X+,r16
>
>     rol r0;   rol r1;   rol r2;   rol r3;   rol r4;   rol r5;   rol
> r6;   rol r7;   rol r8;   rol r9;
>     clt
>     bld r0,0
>
>     reti
>
> ext_int_1:
>     in r16,TCNT1H
>     st X+,r16
>     in r16,TCNT1L
>     st X+,r16
>
>     rol r0;   rol r1;   rol r2;   rol r3;   rol r4;   rol r5;   rol
> r6;   rol r7;   rol r8;   rol r9;
>     set
>     bld r0,0
>
>     reti
> ----------------
> I should always get 9 registers full of
> "...010101010101010101010101010101..."
> In stead, I get 9 registers full of "...000000000001001000000000000010..."
> UNLESS...I take out the two "st X,TCNT1x" lines. If I do that it works
> great.

It is difficult to understand results of `st X+,TCNT1*' instructions with
values less than 0x60 or higher than 0x15F (for 2313 chip) of r26.
(Value of r27 is ignored in such instruction by this chip).

Regards.