mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-05 11:06:53 +00:00
129 lines
1.9 KiB
ArmAsm
129 lines
1.9 KiB
ArmAsm
; Tilted Plane, based on the code in Hellmood's Memories
|
|
|
|
; by deater (Vince Weaver) <vince@deater.net>
|
|
|
|
; Zero Page
|
|
BASL = $28
|
|
BASH = $29
|
|
H2 = $2C
|
|
COLOR = $30
|
|
|
|
X1 = $F0
|
|
X2 = $F1
|
|
Y1 = $F2
|
|
Y2 = $F3
|
|
|
|
|
|
M1 = $F7
|
|
M2 = $F8
|
|
|
|
TEMP = $FA
|
|
TEMPY = $FB
|
|
FRAME = $FC
|
|
TEMPX = $FD
|
|
SCALED = $FE
|
|
|
|
|
|
; Soft Switches
|
|
KEYPRESS= $C000
|
|
KEYRESET= $C010
|
|
SET_GR = $C050 ; Enable graphics
|
|
FULLGR = $C052 ; Full screen, no text
|
|
PAGE0 = $C054 ; Page0
|
|
PAGE1 = $C055 ; Page1
|
|
LORES = $C056 ; Enable LORES graphics
|
|
|
|
; ROM routines
|
|
|
|
PLOT = $F800 ; plot, horiz=y, vert=A (A trashed, XY Saved)
|
|
SETCOL = $F864
|
|
TEXT = $FB36 ;; Set text mode
|
|
BASCALC = $FBC1
|
|
SETGR = $FB40
|
|
HOME = $FC58 ;; Clear the text screen
|
|
WAIT = $FCA8 ;; delay 1/2(26+27A+5A^2) us
|
|
HLINE = $F819
|
|
|
|
tilted_plane:
|
|
|
|
|
|
|
|
;===================
|
|
; init screen
|
|
jsr SETGR ; 3
|
|
bit FULLGR ; 3
|
|
|
|
jsr init_multiply_tables
|
|
|
|
plane_forever:
|
|
|
|
inc FRAME ; 2
|
|
|
|
ldx #47 ; yy ; 2
|
|
yloop:
|
|
ldy #39 ; xx ; 2
|
|
xloop:
|
|
|
|
; clc
|
|
; adc #$10 ; adjust top of screen
|
|
lda division,X ; scaled=((0x3d5/yy)&0xff);
|
|
; reverse divide AL=C/Y'
|
|
|
|
sta M1
|
|
sta SCALED
|
|
|
|
; color=((signed char)((xprime-20)&0xff))*((signed char)(scaled&0xff));
|
|
tya
|
|
sec
|
|
sbc #20
|
|
sta M2
|
|
|
|
jsr multiply_s8x8
|
|
|
|
lda M1
|
|
|
|
rol
|
|
rol M2
|
|
rol
|
|
rol M2
|
|
|
|
lda M2
|
|
sta COLOR
|
|
|
|
; fedcba9876543210
|
|
; dcba9876
|
|
|
|
|
|
; color=(color>>6)&0xff;
|
|
|
|
sec
|
|
lda SCALED
|
|
sbc FRAME ; scaled-=frame;
|
|
eor COLOR ; color^=(scaled&0xff);
|
|
and #$1C ; color&=0x1c; // map colors
|
|
|
|
jsr SETCOL
|
|
|
|
txa ; A==Y1 ; 1
|
|
jsr PLOT ; (X2,Y1) ; 3
|
|
|
|
dey ; 1
|
|
bpl xloop ; 2
|
|
|
|
dex ; 1
|
|
bpl yloop ; 2
|
|
|
|
bmi plane_forever ; 2
|
|
|
|
|
|
division:
|
|
.byte $62,$59,$51,$4B,$46,$41,$3D,$39,$36,$33
|
|
.byte $31,$2E,$2C,$2A,$28,$27,$25,$24,$23,$21
|
|
.byte $20,$1F,$1E,$1D,$1C,$1C,$1B,$1A,$19,$19
|
|
.byte $18,$17,$17,$16,$16,$15,$15,$14,$14,$14
|
|
.byte $13,$13,$12,$12,$12,$11,$11,$11
|
|
|
|
.include "multiply_tables.s"
|
|
.include "multiply_s8x8.s"
|
|
.include "multiply_u8x8.s"
|