A86: FindPixel Routine

To: assembly-86@lists.ticalc.org
Subject: A86: FindPixel Routine
From: Ti86ROM@aol.com
Date: Thu, 4 Jun 1998 23:07:05 EDT
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


The Pebble Chop Pebble Pebble Pebble Chop Chop Fast Find Pixel Routine:

I thought of this routine on the bus, can some1 please check it for accuracy +
speed?

rr a does this, right?:
%11110010
%01111001
%00111100
%00011110

and rrc does this, right?:
%11110010
%01111001
%10111100
%01011110

If i'm wrong on those two then swap them around in my routine, k? i couldn't
find very good help.

d=X
e=Y
hl=byte
a=bitmask


FindPixel:
rr d
rr d
rr d
ld h,d
ld a,e
and 1
rrca
add a,h
ld h,a

rr e
ld a,e
add a,$FC
ld l,a

ld a,128
ld c,a
ld a,d
and 7
RLoop:
cp 0
jr z,RLoopEnd
rr c
dec a
fr RLoop
RLoopEnd:
ld a,c
ret

Follow-Ups:

Re: A86: FindPixel Routine

From: Dan Eble <eble@cis.ohio-state.edu>