Assembly Instructions?

[CIA_MAN275]

Hey Guys!

I need help!

I want an assembly instruction for those c-commands:

 DDRH |= 0x80;

 and

PORTH ^=0x80;

Aim is to switch the light off an on! I am a rookie yes

THX!!

[HSW]

There is a S12 opcode for setting a bit in memory:

   BSET DDRH #$80

To toggle bit 7 you could implement the following sequence:

    LDAA    #$80

    ADDA    PORTH

    STAA     PORTH

[CIA_MAN275]

Can you also explain me the following code:

  ADDA    PORTH

why do you this?

[Lundin]

Fundamental Boolean algebra: A + B equals A UNION B equals A OR B

[kef]

Why? To be smarter than average, probably :-). ADD isn't faster than EOR, so this trick is as useless as this one

   LDAA PORTH   ;// PORTH ^= 0x80

   SUBA  #$80

   STAA  PORTH

Your successor will like it..., or maybe not

[CIA_MAN275]

When you make -> A= A- $80 than you become the led light off or?

I mean this explanation also above!

THX!!!

[kef · Accepted solution]

A = A -+ 0x80 will toggle bit7 of A. Will it make LED connected to PORTH on or off I don't know, it depends on initial state of PORTH, also on the circuit.

[CIA_MAN275]

Okay THX!!!!

Here is the whole code:

include <stdio.h>

#include <mc912d128.h>


void delay1ms(void) {
  asm("ldy #2666"); //2666 in Y-Register laden
  asm("dbne y,.");  // Decrement, bis Y=0 ist /
            //3cyc x 125ns x 2666 = 0,99975ms
}


void wait(int duration)
{
  while(duration--)
  delay1ms();
}

void main(void) {

 asm("LDAA #$80");               //DDRH |= 0x80;
 asm("STAA $002B");


while(1){
  asm("LDAA #$80");           //PORTH ^=0x80;
  asm("ADDA $0029");
  asm("STAA $0029");
  wait(1000);
 
  }

}

Program is ICC12!

THX to all of you for helping hands!

[CIA_MAN275]

I have no S12... so the code don't work!