A86: How do you get the value in OP1 into a register?

To: assembly-86@lists.ticalc.org, Robert A Johnson <johns627@tc.umn.edu>
Subject: A86: How do you get the value in OP1 into a register?
From: Blake Johnson <johns627@tc.umn.edu>
Date: Sun, 24 May 1998 16:52:18 -0500
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


I have been trying to port this TI-BASIC program that I made into
assembly because it runs SOOO slow.  Here is the program:
:ClDrw:FnOff
:PlOff :AxesOff
:Goto start
:Lbl plot
:PxOn(iPart (64-Y*64),x)
:Goto A
:Lbl start
:For(x,0,127)
:2.5+(x/84)->X
:0.5->Y
:For(N,0,150)
:X*Y(1-Y)->Y
:If N>100
:Goto plot
:Lbl A
:End
:End
Anyways, I was trying to convert this into assembly and I ran into a
problem.  I'll show the source before attempting to explain my problem.
It's kind of long so please, just stay with me.
#include "ti86asm.inc"
#include "Ti86math.inc"
#include "TI86ops.inc"

.org _asm_exec_ram

  call _clrLCD
  ld e,0                          ;e = x counter and x coordinate of
screen
XLOOP:
  ld a,e                          ;2.5+(x/84), OP1=x
  call _SetXXOP1
  ld a,84                        ;OP2=84
  call _SetXXOP2
  call _FPDIV                ;OP1=x/84
  ld hl, TWOPT5
  call _MOV10TOOP2  ;OP2=2.5
  call _FPADD              ;OP1=2.5+(x/84)
  call _OP1TOOP5        ;OP5=OP1, OP5 will store X for calculations
  ld hl, PT5                    ;y = .5
  call _MOV10TOOP2  ;OP2=y
  call _OP2TOOP6        ;OP6=y
  ld c,0                           ;c = iteration counter
CALC:
  call _OP6TOOP1         ;OP1=y
  call _OP2SET1            ;OP2=1
  call _FPSUB                ;OP1=y-1
  call _OP6TOOP2        ;OP2=y
  call _FPMULT            ;OP1=y(y-1)
  call _OP5TOOP2        ;OP2=x
  call _FPMULT            ;OP1=x*y(y-1)
  call _OP1TOOP6        ;y now equals new value
  ld a,c
  ld b,100       ;if c>100 goto PLOT
  cp b
  jr nc, Plot
Return:
  inc c
  ld a,c
  ld b,150       ;if c>150 next x
  cp b
  jr nz, CALC
  inc e            ;increment x counter
  ld a,e
  ld b,128
  cp b
  jr nz, XLOOP
  call _getkey
  call _clrLCD
  ret


TWOPT5: .db $00, $00, $FC, $25, $00, $00, $00, $00, $00, $00
PT5: .db $00, $FE, $FB, $50, $00, $00, $00, $00, $00, $00

Plot:
  call _OP6TOOP1    ;OP1=y
  ld a,64
  call _SetXXOP2      ;OP2=64
  call _FPMULT         ;OP1=y*64
  call _OP1TOOP2     ;OP2=OP1
  call _SetXXOP1      ;OP1=64
  call _FPSUB            ;OP1=64-y*64
  call _INTGR            ;get integer value of OP1
;what do I need to put in order to get d to equal the value in OP1
  ld d,0                       ;this line is here because I just wanted
to test and see if the rest worked
  call FindPixel
  or (hl)
  ld (hl), a
  jr Return

FindPixel:
  ld hl,FP_Bits
  ld a,e
  and %00000111
  add a,l
  ld l,a
  adc a,h
  sub l
  ld h,a
  ld c,(hl)
  ld hl,FP_RLD
  ld (hl),d

  ld a,e
  rrca
  rrca
  rrca
  rld
  or $FC
  ld l,(hl)
  ld h,a
  ld a,c
  ret

FP_RLD: .db $00
FP_Bits: .db $80,$40,$20,$10,$08,$04,$02,$01
.end

Okay, now back to the problems.  As I put in the comments, I don't know
how to get the value in OP1 into the d register so that the findpixel
routine can run.  Also, when I ran the above code I got an overflow
error.  Any ideas why?  Also, since I'm just a beginning asm programmer
(thanks Matt for your very helpful page) any other errors that you could
find and help me out with would be greatly appreciated.  Thanks.

--Blake Johnson