AVR-Chat

On 29 Sep 2006 at 10:34, David VanHorn wrote:

> >
> >
> >        ldi ZH, high(TABLE*2)
> >        ldi ZL,  low(TABLE*2)
> >
> >        lpm temp, Z+
> >        lpm temp, Z+
> >        lpm temp, Z+
> >        lpm temp, Z+
> >        lpm temp, Z+
> >
> >        Question:
> >
> >        - What is the current value of ZH:ZL?
> 
> 
> You could just walk that through the sim and see how it works.
> Z increments byte by byte, not word, so it's 2.5 words up from the start of
> TABLE
> 
> When you set Z, you're loading in Table*2, and the LSB selects which byte
> you get, 0=low, 1=high
> This is why we have the ELPM instruction, for the larger chips.
> 
> 

	Hi David, thanks for the explanation.
	My problem is how to find the LPM passed the end of table
by looking at the ZH:ZL register.

	I tried the code below, but it is not working:

read:
	lpm register, Z+

	ldi temp, high(ENDTABLE*2)
	cp ZL, low(ENTABLE*2)
	cpc ZH, temp
	brlo read

	ret


TABLE:
.db "Hello world!"
.db "Hello world!"
.db "Hello world!"
.db "Hello world!"
.db "Hello world!"
.db "Hello world!"
ENDTABLE: