Re: [avr-gcc-list] How to reserve registers

[Georg-Johann Lay]

Paulo Marques wrote:

> push    r0
> in      r0, SREG
> push    r1
> eor   r1, r1
> push    r2
> 
> sec
  ^^^
Superfluous

> in    r2, GPIOR0
> adc   r2, r1

Why using ADC? AVR has INC (increment by 1) instruction that works with any
register.

> out     GPIOR0, r2
> in    r2, GPIOR1
> adc   r2, r1

ditto

> out     GPIOR1, r2
> in    r2, GPIOR2
> adc   r2, r1

ditto

> out     GPIOR2, r2
> lds   r2, high_counter_byte
> adc   r2, r1

ditto

> sts     high_counter_byte, r2
> 
> pop   r2
> pop   r1
> out   SREG, r0
> pop   r0
> reti