A86: Re: WTF is wrong with this routine?

To: <assembly-86@lists.ticalc.org>
Subject: A86: Re: WTF is wrong with this routine?
From: "Matt2000" <matt2000@gte.net>
Date: Mon, 8 Jun 1998 14:36:32 -0400
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


>It doesn't work right!  help me!?


I dont know but my god that is a slow way to multiply HL by 128. I mean,
cant you replace this:

 ld  h,0     ;hl = yCoord
 add  hl,hl    ;*2
 add  hl,hl    ;*4
 add  hl,hl    ;*8
 add  hl,hl    ;*16 - Each row is 16 bytes long
 add  hl,hl    ;*32
 add  hl,hl    ;*64
 add  hl,hl    ;*128 - Skip 8 rows for each sprite

with this (33 clocks I believe):

xor a             ; Clear A
ld h, a           ; Clear H
ld h, l            ; Multiply by 256
srl h             ; Divide by 2
adc a, 0      ; Add carry to A
ld l, a           ; Put it in L

It should work - or something similar. But each add hl, hl takes 11 clock
cycles and that right there is 77 clocks plus the ld h, 0
which is another 7 clocks

So why doesnt your routine work? I have no idea what you are trying to do
and you conviently failed to mention that. It appears
to be some aligned sprite routine I guess, are you trying to make an RPG or
something?

Later,
    Matt

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