Assembler question

micman2

Hi all,

I've a question about the load variable:
I use viewport for read into the variable

When I'd write in temp1 with 100 , work! (screen "a" and "a1" file in a1 see variable "v2")

              mov temp1,#100

but when I load temp1 with variable "Delay" not work!!!(screen "b" and "b1" file see variable "v2")

              mov temp1,Delay

              Delay         long    100

Send screen

Mike Green

The problem is your Delay declaration. You can't have a LONG declaration in the middle of a series of RES declarations. The RES declarations must always come last in the cog program.

micman2

How I do ?

and another question , If I would load variabile with 1000 I have a error! but the register is 32bit?!

Ale

The literal immediate (using #) is limited to values between 0 and 511. Use a variable to load bigger constants (like you do in your second example above). (Read the multiple assembler tutorials that the first sticky in the forum has [noparse]:D[/noparse], it will dissipate loads of doubts.

micman2

Ok tanks!!!

Another question

I would developement delay but without use waitcnt

My simple code:

'---------delay
                  mov temp,cnt
                  add temp,Delay
mylop         cmp temp,cnt
IF_B           jmp mylop                    ' if temp is below cnt counter
          
'........... 


Delay         long    4_000_000

temp res 1
                                           

Is it correct?

Mike Green

This will work better:

                  mov  startTime,cnt             ' Save starting time
delayLoop   mov  temp,cnt
                  sub   temp,startTime          ' Compute difference between now and starting time
                  cmp  temp,Delay        wc    ' Is difference less than desired delay
        if_b     jmp  #delayLoop               ' If so, continue to wait

The reason for comparing to the time difference is that it avoids problems when the time wraps around (in the 32 bit register).

micman2

Thank thank!!

Ale

In your example, you are jumping _after_ the addition, so you are always comparing and jumping but never adding