dos33fsprogs/graphics/gr/rotozoom/rotozoom.s
2021-01-20 00:26:16 -05:00

629 lines
12 KiB
ArmAsm

; rotozoomer!
; takes a lores-formatted image in $c00 and rotozooms it
; by ANGLE and SCALE_I/SCALE_F and draws it to the
; lo-res page in DRAW_PAGE
; ANGLE in our case is 0..31
; SCALE_I/SCALE_F is 8.8 fixed point scale multiplier
; optimization (cycles measured at ANGLE=0)
; $6BD76=441,718=2.26fps initial code with external plot and scrn
; $62776=403,318=2.48fps inline plot
; $597b6=366,518=2.73fps inline scrn
; $4F496=324,758=3.08fps move plot line calc outside of inner loop
; $49d16=302,358=3.31fps do color*17 ourselves
; $4645e=287,838=3.47fps move XX into X
; $3ef7e=257,918=3.87fps optimize plot
; $3c9fe=248,318=4.03fps optimize scrn
; $39e3e=237,118=4.22fps add scrn address lookup table
; $39fdf=237,535 add two scale multiplies
; $39e17=237,079=4.22fps change the init to also use multiply
; $39dc9=237,001= change to use common lookup table (outside inner loop)
; $3399f=211,359=4.73fps unroll the Y loop by one
; $2BA83=178,819=5.59fps optimize unrolled loop
; $2B14B=176,459=5.66fps avoid extra jump (qkumba)
CAL = $B0
CAH = $B1
SAL = $B2
SAH = $B3
YPL = $B4
YPH = $B5
XPL = $B6
XPH = $B7
;YY
;XX
CCAL = $B8
CCAH = $B9
CSAL = $BA
CSAH = $BB
YCAL = $BC
YCAH = $BD
YSAL = $BE
YSAH = $BF
rotozoom:
; setup scale for multiply
lda SCALE_I ; 3
sta NUM1H ; 3
lda SCALE_F ; 3
sta NUM1L ; 3
; ca = cos(theta)*scale;
; (we use equiv ca=fixed_sin[(theta+8)&0xf] )
lda ANGLE ; 3
clc ; 2
adc #8 ; 2
and #$1f ; 2
asl ; 2
tay ; 2
lda fixed_sin,Y ; load integer half ; 4
sta NUM2H ; 3
lda fixed_sin+1,Y ; load float half ; 4
sta NUM2L ; 3
;===========
; 27
sec ; reload NUM1H/NUM1L ; 2
jsr multiply ; 6+???
stx CAH ; 3
sta CAL ; 3
; sa = sin(theta)*scale;
lda ANGLE ; 3
asl ; 2
tay ; 2
lda fixed_sin,Y ; load integer half ; 4
sta NUM2H ; 3
lda fixed_sin+1,Y ; load integer half ; 4
sta NUM2L ; 3
;==========
; 21
clc ; NUM1H/NUM1L same as last time ; 2
jsr multiply ; 6+???
stx SAH ; 3
sta SAL ; 3
; cca = -20*ca;
lda #-20 ; 2
sta NUM1H ; 3
lda #0 ; 2
sta NUM1L ; 3
lda CAL ; 3
sta NUM2L ; 3
lda CAH ; 3
sta NUM2H ; 3
sec ; reload NUM1H/NUM1L ; 2
jsr multiply ; 6+???
stx CCAH ; 3
sta CCAL ; 3
; csa = -20*sa;
lda SAL ; 3
sta NUM2L ; 3
lda SAH ; 3
sta NUM2H ; 3
clc ; same NUM1H/NUM1L as las time ; 2
jsr multiply ; 6+???
stx CSAH ; 3
sta CSAL ; 3
; yca=cca+ycenter;
lda CCAL ; 3
sta YCAL ; 3
clc ; 2
lda CCAH ; 3
adc #20 ; 2
sta YCAH ; 3
;===========
; 16
; ysa=csa+xcenter;
lda CSAL ; 3
sta YSAL ; 3
clc ; 2
lda CSAH ; 3
adc #20 ; 2
sta YSAH ; 3
;===========
; 16
; yloop, unrolled once
;===================================================================
; for(yy=0;yy<40;yy++) {
;===================================================================
ldy #0 ; 2
sty YY ; 3
rotozoom_yloop:
; setup self-modifying code for plot
; YY already in Y from end of loop
; ldy YY ; 3
lda common_offsets_l,Y ; lookup low-res memory address ; 4
sta rplot2_smc+1 ; 4
sta rplot12_smc+1 ; 4
sta rplot22_smc+1 ; 4
clc ; 2
lda gr_400_offsets_h,Y ; 4
adc DRAW_PAGE ; add in draw page offset ; 3
sta rplot2_smc+2 ; 4
sta rplot12_smc+2 ; 4
sta rplot22_smc+2 ; 4
;=====================
; unroll 0, even line
;=====================
; xp=cca+ysa; 8.8 fixed point
clc ; 2
lda YSAL ; 3
adc CCAL ; 3
sta XPL ; 3
lda YSAH ; 3
adc CCAH ; 3
sta XPH ; 3
;==========
; 20
; yp=yca-csa; 8.8 fixed point
sec ; 2
lda YCAL ; 3
sbc CSAL ; 3
sta YPL ; 3
lda YCAH ; 3
sbc CSAH ; 3
sta YPH ; 3
;===========
; 20
; for(xx=0;xx<40;xx++) {
ldx #0 ; 2
rotozoom_xloop:
;===================================================================
;===================================================================
; note: every cycle saved below here
; saves 1600 cycles
;===================================================================
;===================================================================
; if ((xp<0) || (xp>39)) color=0;
; else if ((yp<0) || (yp>39)) color=0;
; else color=scrn_page(xp,yp,PAGE2);
; we know it's never going to go *that* far out of bounds
; so we could avoid the Y check by just having "0"
; on the edges of the screen? Tricky due to Apple II
; interlacing
roto_color_even_smc:
lda #0 ; default color ; 2
ldy XPH ; 3
bmi rplot ; 2nt/3
cpy #40 ; 2
bcs rplot ; 2nt/3
ldy YPH ; 3
bmi rplot ; 2nt/3
cpy #40 ; 2
bcs rplot ; 2nt/3
;==================================================
; scrn(xp,yp)
tya ; YPH ; 2
lsr ; divide to get index, also low bit in carry ; 2
tay ; 2
; TODO: put these in zero page?
; also we can share low bytes with other lookup
lda common_offsets_l,Y ; lookup low-res memory address ; 4
sta BASL ; 3
lda scrn_c00_offsets_h,Y ; 4
sta BASH ; 3
ldy XPH ; 3
lda (BASL),Y ; top/bottom color ; 5+
; carry was set a bit before to low bit of YPH
; hopefully nothing has cleared it
bcc rscrn_adjust_even ; 2nt/3
rscrn_adjust_odd:
; YP was odd so want top nibble
lsr ; 2
lsr ; 2
lsr ; 2
lsr ; 2
; fall through
rscrn_adjust_even:
; YP was even so want bottom nibble
and #$f ; 2
rscrn_done:
;=============================================
; always even, want A in bottom of nibble
; so we are all set
rotozoom_set_color:
; want same color in top and bottom nibbles
;==========
; 0
;=================================================
rplot:
; plot(xx,yy); (color is in A)
; we are in loop unroll0 so always even line here
; meaning we want to load old color, save top nibble, and over-write
; bottom nibble with our value
; but! we don't need to save old as we are re-drawing whole screen!
rplot_even:
rplot2_smc:
sta $400,X ; 5
;============
; 5
;=======================
; xp=xp+ca; fixed point 8.8
clc ; 2
lda CAL ; 3
adc XPL ; 3
sta XPL ; 3
lda CAH ; 3
adc XPH ; 3
sta XPH ; 3
; yp=yp-sa; fixed point 8.8
sec ; 2
lda YPL ; 3
sbc SAL ; 3
sta YPL ; 3
lda YPH ; 3
sbc SAH ; 3
sta YPH ; 3
rotozoom_end_xloop:
inx ; 2
cpx #40 ; 2
bne rotozoom_xloop ; 2nt/3
rotozoom_xloop_done:
; yca+=ca; 8.8 fixed point
clc ; 2
lda YCAL ; 3
adc CAL ; 3
sta YCAL ; 3
lda YCAH ; 3
adc CAH ; 3
sta YCAH ; 3
;===========
; 20
; ysa+=sa; 8.8 fixed point
clc ; 2
lda YSAL ; 3
adc SAL ; 3
sta YSAL ; 3
lda YSAH ; 3
adc SAH ; 3
sta YSAH ; 3
;==========
; 20
;===============
; loop unroll 1
;===============
;rotozoom_yloop:
; xp=cca+ysa; 8.8 fixed point
clc ; 2
lda YSAL ; 3
adc CCAL ; 3
sta XPL ; 3
lda YSAH ; 3
adc CCAH ; 3
sta XPH ; 3
;==========
; 20
; yp=yca-csa; 8.8 fixed point
sec ; 2
lda YCAL ; 3
sbc CSAL ; 3
sta YPL ; 3
lda YCAH ; 3
sbc CSAH ; 3
sta YPH ; 3
;===========
; 20
; for(xx=0;xx<40;xx++) {
ldx #0 ; 2
rotozoom_xloop2:
;===================================================================
;===================================================================
; note: every cycle saved below here
; saves 1600 cycles
;===================================================================
;===================================================================
; if ((xp<0) || (xp>39)) color=0;
; else if ((yp<0) || (yp>39)) color=0;
; else color=scrn_page(xp,yp,PAGE2);
; we know it's never going to go *that* far out of bounds
; so we could avoid the Y check by just having "0"
; on the edges of the screen? Tricky due to Apple II
; interlacing
roto_color_odd_smc:
lda #0 ; default color ; 2
ldy XPH ; 3
bmi rplot2 ; 2nt/3
cpy #40 ; 2
bcs rplot2 ; 2nt/3
ldy YPH ; 3
bmi rplot2 ; 2nt/3
cpy #40 ; 2
bcs rplot2 ; 2nt/3
;==================================================
; scrn(xp,yp)
tya ; YPH ; 2
lsr ; divide to get index, also low bit in carry ; 2
tay ; 2
; TODO: put these in zero page?
; also we can share low bytes with other lookup
lda common_offsets_l,Y ; lookup low-res memory address ; 4
sta BASL ; 3
lda scrn_c00_offsets_h,Y ; 4
sta BASH ; 3
ldy XPH ; 3
lda (BASL),Y ; top/bottom color ; 5+
; carry was set a bit before to low bit of YPH
; hopefully nothing has cleared it
bcs rscrn_adjust_odd2 ; 3
rscrn_adjust_even2:
; want bottom color, but put it in top of A
asl ; 2
asl ; 2
asl ; 2
asl ; 2
jmp rscrn_done2 ; 3
rscrn_adjust_odd2:
; want top color alone
and #$f0 ; 2
rscrn_done2:
;=============================================
rotozoom_set_color2:
; always odd
; want color in top, which it is from above
;==========
; 0
;=================================================
rplot2:
; plot(xx,yy); (color is in A)
; always odd, so place color in top
; note! since we are drawing whole screen, we know the top of
; the value is already clear from loop=0 so we don't have to mask
rplot_odd:
rplot12_smc:
ora $400,X ; 4
rplot22_smc:
sta $400,X ; 5
;============
; 9
;=======================
; xp=xp+ca; 8.8 fixed point
clc ; 2
lda CAL ; 3
adc XPL ; 3
sta XPL ; 3
lda CAH ; 3
adc XPH ; 3
sta XPH ; 3
; yp=yp-sa; 8.8 fixed point
sec ; 2
lda YPL ; 3
sbc SAL ; 3
sta YPL ; 3
lda YPH ; 3
sbc SAH ; 3
sta YPH ; 3
rotozoom_end_xloop2:
inx ; 2
cpx #40 ; 2
bne rotozoom_xloop2 ; 3
rotozoom_xloop_done2:
; yca+=ca; 8.8 fixed point
clc ; 2
lda YCAL ; 3
adc CAL ; 3
sta YCAL ; 3
lda YCAH ; 3
adc CAH ; 3
sta YCAH ; 3
;===========
; 20
; ysa+=sa; 8.8 fixed point
clc ; 2
lda YSAL ; 3
adc SAL ; 3
sta YSAL ; 3
lda YSAH ; 3
adc SAH ; 3
sta YSAH ; 3
;==========
; 20
rotozoom_end_yloop:
inc YY ; 5
ldy YY ; 3
cpy #20 ; 2
beq done_rotozoom ; 2nt/3
jmp rotozoom_yloop ; too far ; 3
done_rotozoom:
rts ; 6
fixed_sin:
; .byte $00,$00 ; 0.000000=00.00
; .byte $00,$61 ; 0.382683=00.61
; .byte $00,$b5 ; 0.707107=00.b5
; .byte $00,$ec ; 0.923880=00.ec
; .byte $01,$00 ; 1.000000=01.00
; .byte $00,$ec ; 0.923880=00.ec
; .byte $00,$b5 ; 0.707107=00.b5
; .byte $00,$61 ; 0.382683=00.61
; .byte $00,$00 ; 0.000000=00.00
; .byte $ff,$9f ; -0.382683=ff.9f
; .byte $ff,$4b ; -0.707107=ff.4b
; .byte $ff,$14 ; -0.923880=ff.14
; .byte $ff,$00 ; -1.000000=ff.00
; .byte $ff,$14 ; -0.923880=ff.14
; .byte $ff,$4b ; -0.707107=ff.4b
; .byte $ff,$9f ; -0.382683=ff.9f
.byte $00,$00 ; 0.000000
.byte $00,$31 ; 0.195090
.byte $00,$61 ; 0.382683
.byte $00,$8E ; 0.555570
.byte $00,$B5 ; 0.707107
.byte $00,$D4 ; 0.831470
.byte $00,$EC ; 0.923880
.byte $00,$FB ; 0.980785
.byte $01,$00 ; 1.000000
.byte $00,$FB ; 0.980785
.byte $00,$EC ; 0.923880
.byte $00,$D4 ; 0.831470
.byte $00,$B5 ; 0.707107
.byte $00,$8E ; 0.555570
.byte $00,$61 ; 0.382683
.byte $00,$31 ; 0.195090
.byte $00,$00 ; 0.000000
.byte $FF,$CF ; -0.195090
.byte $FF,$9F ; -0.382683
.byte $FF,$72 ; -0.555570
.byte $FF,$4B ; -0.707107
.byte $FF,$2C ; -0.831470
.byte $FF,$14 ; -0.923880
.byte $FF,$05 ; -0.980785
.byte $FF,$00 ; -1.000000
.byte $FF,$05 ; -0.980785
.byte $FF,$14 ; -0.923880
.byte $FF,$2C ; -0.831470
.byte $FF,$4B ; -0.707107
.byte $FF,$72 ; -0.555570
.byte $FF,$9F ; -0.382683
.byte $FF,$CF ; -0.195090