[TI ASM] Asm Help

[L-Man]

well ionlargesprite uses the adress of ix to find the sprite right? well why cant you load the adress somewhere else like this:

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ld hl,TempSprite
ld (hl),MarioSprite

is there some way to do this?

[kv83]

yes, you can store the adress in hl... if you want to to retrieve to get the adress from hl to ix, you can do that by simply:

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push hl
pop ix

I am not sure if that's what you asking though

[L-Man]

no not really!
k i want to load the adress of a sprite MarioRight in to a temporary variable called TempSprite so i can call ionlargesprite with
ld ix,TempSprite
and having tempsprite have the adress of MarioRight so when i call ionlargesprite it loads MarioRight Sprite.

Thats my question

[kv83]

than you need two variables, because a adress is a 16bit register.

storing the adress (located in hl) would go like

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ld a,h
ld (tempSpriteAdress),a
ld a,l
ld (tempSpriteAdress+1),a

and I think you can guess how loading goes...

to use it with the ion routine, you have to load it of course... it's not just simply ix,tempspriteadress... there is a difference between loading data and loading a pointer

[tr1p1ea]

If you want to store it in HL you would have to do something akin to:

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ld a,(hl)
inc hl
ld h,(hl)
ld l,a

[kv83]

I don't think what you are trying to do is possible tr1p...

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ld a,(hl) 
inc hl 
ld h,(hl) 
ld l,a

would be rather:

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ld a,(hl) 
ld b,a
inc hl
ld a,(hl)
ld h,a
ld l,b

[CoBB]

You're wrong, Vincent, and tr1p is right. Also, referring to your previous post, LD (ArbitraryAddress), HL is also possible. Check out my LD table if you don't believe me. BTW you have some endianness problem there, the high byte comes after the low byte in the Z80.

[kv83]

You're wrong, Vincent, and tr1p is right. Check out my LD table if you don't believe me.

Hmmm... I already was afraid, that my thoughts would be wrong ... Don't worry, how couldn't I believe one of the z80 gods

Also, referring to your previous post, LD (ArbitraryAddress), HL is also possible.

so if you do LD (ArbitraryAddress),HL where will it go? It doesn't fit in a 8bit register I suppose, so it most likely will use both (ArbitraryAddress) and (ArbitraryAddress+1),right? and does that mean that LD HL,(Arbitrary Adress) does also work?

BTW you have some endianness problem there, the high byte comes after the low byte in the Z80.

endianness problem? I don't get it...

[CoBB]

As stated in my previous post: the low byte goes to Address, the high byte to Address+1. And yes, it's possible the other way around, too.

Endianness is exactly the specification of byte order. Z80 and Intel CPUs are little endian, i. e. numbers are stored with their lowest byte first. As opposed to this, Motorola CPUs are bigendian, storing everything in the exact opposite order.

[tr1p1ea]

Yes so if you were to store say $FEBC at your ArbitraryAddress (on a z80), in memory it would look like:

(ArbitraryAddress) = $BC
(ArbitraryAddress+1) = $FE

[L-Man]

so if im understanding correctly from you guys i can do this:

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ld hl,MarioSprite
ld (TempSprite),hl
....
....
...
ld ix,TempSprite
call ionlargeSprite
call ionfastcopy

right or am i not using inderection? or something else
thanks

[CalcKing]

Since you stored hl (the pointer) to the memory location TempSprite, you will have to use indirection to get the pointer data into ix.

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ld hl,MarioSprite
ld (TempSprite),hl
....
....
...
ld ix,(TempSprite)
call ionlargeSprite
call ionfastcopy

[CoBB]

Actually, it's not that hard to see how it works. All you have to understand is that every symbol (labels you defined) is turned into a number. If TempSprite is $9000 and MarioSprite $9876 for instance, the resulting code will be:

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ld hl,$9876
ld ($9000),hl

Now obviously, if you want to retrieve the value stored at $9000, you shouldn't write

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ld ix,$9000

since that sets ix to $9000 by definition.

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ld ix,($9000)

does the job, ix will be $9876 unless you overwrote the byte at $9000 or $9001 in the meantime.

[L-Man]

You guys are awesome!!!!!! I get it now!

[tr1p1ea]

You know that you can also do:

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ld hl,TempSprite
push hl
pop ix

This is only if you want to get whats in hl to ix ... which i dont know if this is what you want or not?