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dos33fsprogs/mode7_demo/mode7.s
Vince Weaver 60c3137e62 mode7_demo: move all code into one dir 
if I mess around with common asm_routines it will mess with the
size optimized demo.  So lock in place the files and make a copy here.
Should have done this once when I was prepping the PoC||GTFO code.
2018-05-21 11:18:33 -04:00

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;.include "zp.inc"
;===========
; CONSTANTS
;===========
CONST_SHIPX EQU 15
CONST_TILE_W EQU 64
CONST_TILE_H EQU 64
CONST_MAP_MASK_X EQU (CONST_TILE_W - 1)
CONST_MAP_MASK_Y EQU (CONST_TILE_H - 1)
CONST_LOWRES_W EQU 40
CONST_LOWRES_H EQU 40
CONST_BETA_I EQU $ff
CONST_BETA_F EQU $80
CONST_SCALE_I EQU $14
CONST_SCALE_F EQU $00
CONST_LOWRES_HALF_I EQU $ec ; -(LOWRES_W/2)
CONST_LOWRES_HALF_F EQU $00
; pre-programmed directions
checkerboard_flying_directions:
.byte $18,$00 ; 24 frames, do nothing
.byte $10,'D' ; 16 frames, turn right
.byte $10,$00 ; 16 frames, do nothing
.byte $f,'A' ; 15 frames, turn left
.byte $10,$00 ; 16 frames, do nothing
.byte $1,'Z' ; start moving forward
.byte $20,$00 ; 32 frames, do nothing
.byte $1,'Q' ; quit
island_flying_directions:
.byte $2,$00 ; 2 frames, do nothing
.byte $1,'Z' ; start moving forward
.byte $10,$00 ; 16 frames, do nothing
.byte $3,'D' ; 3 frames, turn right
.byte $1,'Z' ; move faster
.byte $8,$00 ; 8 frames, do nothing
.byte $2,'D' ; 2 frames, turn left
.byte $8,$00 ; 8 frames, do nothing
.byte $3,'A' ; 3 frames, turn left
.byte $1,'Z' ; speedup
.byte $8,$00 ; 8 frames, do nothing
.byte $6,'S' ; 6 frames down
.byte $6,$00 ; 6 frames do nothing
.byte $3,'A' ; 3 frames left
.byte $3,'D' ; 3 frames right
.byte $2,$00 ; 2 frames nothing
.byte $1,'D' ; 1 frame right
.byte $2,$00 ; 2 frames nothing
.byte $8,'D' ; 8 frame right
.byte $1,'Z' ; 8 frames up
.byte $6,'W' ; 2 speedup
.byte $a,$00 ; 10 nothing
.byte $3,'S' ; 3 down
.byte $1,'Q' ; quit
;=====================
; Flying
;=====================
mode7_flying:
;================================
; Clear screen and setup graphics
;================================
jsr clear_screens ; clear top/bottom of page 0/1
jsr set_gr_page0
;===============
; Init Variables
;===============
lda #20
sta SHIPY
lda #0
sta TURNING
sta ANGLE
sta SPACEX_I
sta SPACEY_I
sta CX_I
sta CX_F
sta CY_I
sta CY_F
sta DRAW_SPLASH
sta SPEED
sta SPLASH_COUNT
sta DISP_PAGE
sta KEY_COUNT
sta KEY_OFFSET
sta FRAME_COUNT
lda #2 ; initialize sky both pages
sta DRAW_SKY
lda #4 ; starts out at 4.5 altitude
sta SPACEZ_I
lda #$80
sta SPACEZ_F
jsr update_z_factor
flying_loop:
lda SPLASH_COUNT ; 3
beq flying_keyboard ; 2nt/3
dec SPLASH_COUNT ; decrement splash count ; 5
flying_keyboard:
; jsr get_key ; get keypress ; 6
lda KEY_COUNT
bne done_key
ldy KEY_OFFSET
direction_smc_1:
lda island_flying_directions,Y
sta KEY_COUNT
iny
direction_smc_2:
lda island_flying_directions,Y
sta LASTKEY
inc KEY_OFFSET
inc KEY_OFFSET
done_key:
dec KEY_COUNT
lda LASTKEY ; 3
cmp #('Q') ; 2
bne check_up ; 3/2nt
; done
rts
check_up:
cmp #('W') ; 2
bne check_down ; 3/2nt
;===========
; UP PRESSED
;===========
lda SHIPY
cmp #17
bcc check_down ; bgt, if shipy>16
dec SHIPY
dec SHIPY ; move ship up
inc SPACEZ_I ; incement height
jsr update_z_factor
lda #0
sta SPLASH_COUNT
check_down:
cmp #('S')
bne check_left
;=============
; DOWN PRESSED
;=============
lda SHIPY
cmp #28
bcs splashy ; ble, if shipy < 28
inc SHIPY
inc SHIPY ; move ship down
dec SPACEZ_I ; decrement height
jsr update_z_factor
bcc check_left
splashy:
lda #10
sta SPLASH_COUNT
check_left:
cmp #('A')
bne check_right
;=============
; LEFT PRESSED
;=============
lda TURNING
bmi turn_left
beq turn_left
lda #$0
sta TURNING
clv
bvc check_right
turn_left:
lda #253 ; -3
sta TURNING
dec ANGLE
inc DRAW_SKY
inc DRAW_SKY
check_right:
cmp #('D')
bne check_speedup
;==============
; RIGHT PRESSED
;==============
lda TURNING ;; FIXME: optimize me
bpl turn_right
lda #0
sta TURNING
clv
bvc check_speedup
turn_right:
lda #3
sta TURNING
inc ANGLE
inc DRAW_SKY
inc DRAW_SKY
check_speedup:
cmp #('Z')
bne check_speeddown
;=========
; SPEED UP
;=========
lda #$8
cmp SPEED
beq check_speeddown
inc SPEED
check_speeddown:
cmp #('X')
bne check_brake
;===========
; SPEED DOWN
;===========
lda SPEED
beq check_brake
dec SPEED
check_brake:
cmp #(' '+128)
bne check_land
;============
; BRAKE
;============
lda #$0
sta SPEED
check_land:
cmp #13
bne check_help
check_help:
cmp #('H')
bne check_done
check_done:
;================
; Wrap the Angle
;================
; FIXME: only do this in right/left routine?
lda ANGLE ; 3
and #$f ; 2
sta ANGLE ; 3
;================
; Handle Movement
;================
speed_move:
ldx SPEED ; 3
beq draw_background ; 2nt/3
;=============
lda ANGLE ; dx.i=fixed_sin[(angle+4)&0xf].i; // cos() ; 3
clc ; 2
adc #4 ; 2
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin_scale,Y ; 4
sta DX_I ; 3
iny ; dx.f=fixed_sin[(angle+4)&0xf].f; // cos() ; 2
lda fixed_sin_scale,Y ; 4
sta DX_F ; 3
lda ANGLE ; dy.i=fixed_sin[angle&0xf].i; // sin() ; 3
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin_scale,Y ; 4
sta DY_I ; 3
iny ; dx.f=fixed_sin[angle&0xf].f; // sin() ; 2
lda fixed_sin_scale,Y ; 4
sta DY_F ; 3
;============
; 54
speed_loop:
clc ; fixed_add(&cx,&dx,&cx); ; 2
lda CX_F ; 3
adc DX_F ; 3
sta CX_F ; 3
lda CX_I ; 3
adc DX_I ; 3
sta CX_I ; 3
clc ; fixed_add(&cy,&dy,&cy); ; 2
lda CY_F ; 3
adc DY_F ; 3
sta CY_F ; 3
lda CY_I ; 3
adc DY_I ; 3
sta CY_I ; 3
dex ; 2
bne speed_loop ; 2nt/3
;============
; 45
;====================
; Draw the background
;====================
draw_background:
jsr draw_background_mode7 ; 6
lda DRAW_BLUE_SKY
bne draw_spaceship
;========================================
;========================================
; DRAW SPHERE CODE
;========================================
;========================================
draw_sphere:
; FIXME: optimize this mess
; draw shadow first
lda FRAME_COUNT
and #$0f
tax
lda gravity,X
cmp #$5
bmi high_shadow
low_shadow:
lda #>sphere_shadow1
sta INH
lda #<sphere_shadow1
sta INL
jmp done_shadow
high_shadow:
lda #>sphere_shadow2
sta INH
lda #<sphere_shadow2
sta INL
done_shadow:
lda #18 ; 2
sta XPOS ; 3
lda #36 ; 2
sta YPOS ; 3
jsr put_sprite
; draw sphere
lda #>sphere0 ; 2
sta INH ; 3
lda #<sphere0 ; 2
sta INL ; 3
lda ANGLE
lsr
tax
lda sphere_offset,X
clc
adc INL
sta INL
lda #0
adc INH
sta INH
lda #18 ; 2
sta XPOS ; 3
lda FRAME_COUNT
and #$0f
tax
lda gravity,X
cmp #10
bne no_click
bit SPEAKER
no_click:
clc
adc #18 ; 3
sta YPOS ; 3
jsr put_sprite ; 6
jmp done_draw_spaceship
done_draw_sphere:
;========================================
;========================================
; DRAW SPACESHIP CODE
;========================================
;========================================
draw_spaceship:
check_over_water:
; See if we are over water
lda CX_I ; 3
sta SPACEX_I ; 3
lda CY_I ; 3
sta SPACEY_I ; 3
jsr lookup_island_map ; 6
sec ; 2
sbc #COLOR_BOTH_DARKBLUE ; 2
sta OVER_LAND ; 3
;===========
; 31
; Calculate whether to draw the splash
lda #0 ; set splash drawing to 0 ; 2
sta DRAW_SPLASH ; 3
lda SPEED ; if speed==0, no splash ; 3
beq no_splash ; 2nt/3
lda TURNING ; 3
beq no_turning_splash ; 2nt/3
lda SHIPY ; 3
cmp #27 ; 2
bcc no_turning_splash ; blt if shipy<25 skip ; 2nt/3
lda #1 ; 2
sta SPLASH_COUNT ; 3
no_turning_splash:
lda OVER_LAND ; no splash if over land ; 3
bne no_splash ; 2nt/3
lda SPLASH_COUNT ; no splash if splash_count expired ; 3
beq no_splash ; 2nt/3
lda #1 ; 2
sta DRAW_SPLASH ; 3
no_splash:
;==============
; Draw the ship
;==============
clv ; 2
lda TURNING ; 3
beq draw_ship_forward ; 2nt/3
bpl draw_ship_right ; 2nt/3
bmi draw_ship_left ;; FIXME: optimize order ; 2nt/3
draw_ship_forward:
lda DRAW_SPLASH ; 2
beq no_forward_splash ; 2nt/3
; Draw Splash
lda #>splash_forward ; 2
sta INH ; 3
lda #<splash_forward ; 2
sta INL ; 3
lda #(CONST_SHIPX+1) ; 2
sta XPOS ; 3
clc ; 2
lda SHIPY ; 3
adc #9 ; 2
and #$fe ; make sure it's even ; 2
sta YPOS ; 3
jsr put_sprite ; 6
;==========
; 33
no_forward_splash:
; Draw Shadow
lda #>shadow_forward ; 2
sta INH ; 3
lda #<shadow_forward ; 2
sta INL ; 3
lda #(CONST_SHIPX+3) ; 2
sta XPOS ; 3
clc ; 2
lda SPACEZ_I ; 3
adc #31 ; 2
and #$fe ; make sure it's even ; 2
sta YPOS ; 3
jsr put_sprite ; 6
lda #>ship_forward ; 2
sta INH ; 3
lda #<ship_forward ; 2
sta INL ; 3
bvc draw_ship ; 3
;===========
; 46
draw_ship_right:
lda DRAW_SPLASH ; 3
beq no_right_splash ; 2nt/3
; Draw Splash
lda #>splash_right ; 2
sta INH ; 3
lda #<splash_right ; 2
sta INL ; 3
lda #(CONST_SHIPX+1) ; 2
sta XPOS ; 3
clc ; 2
lda #36 ; 2
sta YPOS ; 3
jsr put_sprite ; 6
;===========
; 28
no_right_splash:
; Draw Shadow
lda #>shadow_right ; 2
sta INH ; 3
lda #<shadow_right ; 2
sta INL ; 3
lda #(CONST_SHIPX+3) ; 2
sta XPOS ; 3
clc ; 2
lda SPACEZ_I ; 3
adc #31 ; 2
and #$fe ; make sure it's even ; 2
sta YPOS ; 3
jsr put_sprite ; 6
lda #>ship_right ; 2
sta INH ; 3
lda #<ship_right ; 2
sta INL ; 3
dec TURNING ; 5
bvc draw_ship ; 3
;==========
; 51
draw_ship_left:
lda DRAW_SPLASH ; 3
beq no_left_splash ; 2nt/3
; Draw Splash
lda #>splash_left ; 2
sta INH ; 3
lda #<splash_left ; 2
sta INL ; 3
lda #(CONST_SHIPX+1) ; 2
sta XPOS ; 3
clc ; 2
lda #36 ; 2
sta YPOS ; 3
jsr put_sprite ; 6
;===========
; 28
no_left_splash:
; Draw Shadow
lda #>shadow_left ; 2
sta INH ; 3
lda #<shadow_left ; 2
sta INL ; 3
lda #(CONST_SHIPX+3) ; 2
sta XPOS ; 3
clc ; 2
lda SPACEZ_I ; 3
adc #31 ; 2
and #$fe ; make sure it's even ; 2
sta YPOS ; 3
jsr put_sprite ; 6
lda #>ship_left ; 2
sta INH ; 3
lda #<ship_left ; 2
sta INL ; 3
inc TURNING ; 5
;==========
; 48
draw_ship:
lda #CONST_SHIPX ; 2
sta XPOS ; 3
lda SHIPY ; 3
sta YPOS ; 3
jsr put_sprite ; 6
;===========
; 17
done_draw_spaceship:
;==================
; flip pages
;==================
jsr page_flip ; 6
inc FRAME_COUNT
;==================
; loop forever
;==================
jmp flying_loop ; 3
update_z_factor:
; we only do the following if Z changes
; fixed_mul(&space_z,&BETA,&factor);
;mul1
lda SPACEZ_I ; 3
sta NUM1H ; 3
; interlude, update SPACEZ_SHIFTED
asl ; 2
asl ; 2
asl ; 2
asl ; 2
asl ; 2
sec ; 2
sbc #8 ; 2
sta spacez_shifted+1 ; 4
lda SPACEZ_F ; 3
sta NUM1L ; 3
lda #CONST_BETA_I ; BETA_I ; 2
sta NUM2H ; 3
lda #CONST_BETA_F ; BETA_F ; 2
sta NUM2L ; 3
sec ; don't reuse old values ; 2
jsr multiply ; 6
stx FACTOR_I ; 3
sta FACTOR_F ; 3
rts ; 6
;===========
; 60
;===========================
; Draw the Mode7 Background
;===========================
draw_background_mode7:
; Only draw sky if necessary
; (at start, or if we have switched to text, we never overwrite it)
lda DRAW_SKY ; 3
beq no_draw_sky ;^2nt/3
;==============
; 6
dec DRAW_SKY ; usually 2 as we redraw both pages ; 5
lda DRAW_BLUE_SKY
bne draw_blue_sky
draw_black_sky:
sta CV
jsr scroll_background
jmp no_draw_sky
draw_blue_sky:
; Draw Sky
; not performance critical as this happens rarely
lda #COLOR_BOTH_MEDIUMBLUE ; MEDIUMBLUE color ; 2
sta COLOR ; 3
lda #0 ; 2
;===========
; 11
sky_loop: ; draw line across screen
ldy #39 ; from y=0 to y=6 ; 2
sty V2 ; 3
ldy #0 ; 2
pha ; 3
jsr hlin_double ; hlin y,V2 at A ; 63+(X*16)
pla ; 4
clc ; 2
adc #2 ; 2
cmp #6 ; 2
bne sky_loop ; 3/2nt
;=============
; (23+63+(X*16))*5
; Draw Hazy Horizon
lda #COLOR_BOTH_GREY ; Horizon is Grey ; 2
sta COLOR ; 3
lda #6 ; draw single line at 6/7 ; 2
ldy #39 ; 2
sty V2 ; hlin Y,V2 at A ; 3
ldy #0 ; 2
jsr hlin_double ; hlin 0,40 at 6 ; 63+(X*16)
;===========
; 63+(X*16)+14
no_draw_sky:
; setup initial odd/even color mask
lda #$f0 ; 2
sta COLOR_MASK ; 3
; start Y at 8 (below horizon line)
lda #8 ; 2
sta SCREEN_Y ; 3
;=============
; 10
screeny_loop:
and #$fe ; be sure SCREEN_Y used later is even ; 2
tay ; put in Y for lookup table later ; 2
lda COLOR_MASK ; flip mask for odd/even row plotting ; 3
eor #$ff ; 2
sta COLOR_MASK ; 3
sta mask_label+1 ; setup self-modifying code ; 4
eor #$ff ; setup self-modifying branch later ; 2
bmi odd_branch ; beq is $f0 (too clever FIXME) ; 2nt/3
lda #$d0 ; bne is $d0 ; 2
odd_branch:
sta mask_branch_label ; actually update branch ; 4
;============
; 27
setup_gr_addr:
lda gr_offsets,Y ; lookup low-res memory row address ; 4
sta GBASL ; store in GBASL zero-page pointer ; 3
iny ; point to high part of address ; 2
lda gr_offsets,Y ; load high part of address ; 4
clc ; clear carry for add ; 2
adc DRAW_PAGE ; add in draw page offset ; 3
sta GBASH ; store in GBASH zero-page pointer ; 3
;=============
; 21
calc_horizontal_scale:
; Calculate the horizontal scale using a lookup table
; horizontal_scale.i *ALWAYS* = 0
; unsigned char horizontal_lookup[7][32];
;horizontal_scale.f=
; horizontal_lookup[space_z.i&0xf][(screen_y-8)/2];
; horizontal_lookup[(space_z<<5)+(screen_y-8)]
clc ; 2
lda SCREEN_Y ; 3
spacez_shifted:
adc #0 ; self-modify, loads (spacez<<5)-8 ; 2
tay ; 2
lda horizontal_lookup,Y ; 4
sta NUM1L ; HORIZ_SCALE_F is input to next mul ; 3
;============
; 16
; mul2
; calculate the distance of the line we are drawing
; fixed_mul(&horizontal_scale,&scale,&distance);
lda #0 ; HORIZ_SCALE_I is always zero ; 2
sta NUM1H ; 3
; NUM1L was set to HORIZ_SCALE_F previously ;
lda #CONST_SCALE_I ; SCALE_I ; 2
sta NUM2H ; 3
lda #CONST_SCALE_F ; SCALE_F ; 2
sta NUM2L ; 3
sec ; don't reuse previous settings ; 2
jsr multiply ; 6
stx DISTANCE_I ; 2
sta DISTANCE_F ; 2
;==========
; 27
; calculate the dx and dy to add to points in space
; we add to the starting values on each row to get the next
; space values
; dx.i=fixed_sin[(angle+8)&0xf].i // -sin()
lda ANGLE ; 3
clc ; 2
adc #8 ; 2
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin,Y ; load integer half ; 4
sta NUM2H ; use as source in upcomnig mul ; 3
; dx.f=fixed_sin[(angle+8)&0xf].f; // -sin()
iny ; point to float half ; 2
lda fixed_sin,Y ; load it from lookup table ; 4
sta NUM2L ; use as source in upcoming mul ; 3
;==========
; 29
;mul3
; fixed_mul(&dx,&horizontal_scale,&dx);
; DX_I:DX_F already set in NUM2H:NUM2L
clc ; reuse HORIZ_SCALE in NUM1 ; 2
jsr multiply ; 6
stx DX_I ; 3
sta DX_F ; 3
;==========
; 14
; dy.i=fixed_sin[(angle+4)&0xf].i; // cos()
lda ANGLE ; 3
clc ; 2
adc #4 ; 2
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin,Y ; load integer half ; 4
sta NUM2H ; use as source in upcoming mul ; 3
; dy.f=fixed_sin[(angle+4)&0xf].f; // cos()
iny ; point to float half ; 2
lda fixed_sin,Y ; load from lookup table ; 4
sta NUM2L ; use as source in upcoming mul ; 3
;==========
; 29
;mul4
; fixed_mul(&dy,&horizontal_scale,&dy);
; DY_I:DY_F already in NUM2H:NUM2L
clc ; reuse horiz_scale in num1 ; 2
jsr multiply ; 6
stx DY_I ; 3
sta DY_F ; 3
;==========
; 14
;=================================
; calculate the starting position
;=================================
; fixed_add(&distance,&factor,&space_x);
clc ; fixed_add(&distance,&factor,&space_y); ; 2
lda DISTANCE_F ; 3
adc FACTOR_F ; 3
sta SPACEY_F ; 3
sta SPACEX_F ; 3
lda DISTANCE_I ; 3
adc FACTOR_I ; 3
sta SPACEY_I ; 3
sta SPACEX_I ; 3
;==========
; 26
; temp.i=fixed_sin[(angle+4)&0xf].i; // cos()
lda ANGLE ; 3
clc ; 2
adc #4 ; 2
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin,Y ; 4
sta NUM2H ; store as source for next mul ; 3
; temp.f=fixed_sin[(angle+4)&0xf].f; // cos()
iny ; 2
lda fixed_sin,Y ; 4
sta NUM2L ; store as source for next mul ; 3
;==========
; 29
; mul5
; fixed_mul(&space_x,&temp,&space_x);
lda SPACEX_I ; 3
sta NUM1H ; 3
lda SPACEX_F ; 3
sta NUM1L ; 3
; NUM2H:NUM2L already set above
sec ; don't reuse previous NUM1 ; 2
jsr multiply ; 6
; SPACEX_I in X ;
; SPACEX_F in A ;
;==========
; 20
; fixed_add(&space_x,&cx,&space_x);
clc ; 2
; SPACEX_F still in A ;
adc CX_F ; 3
sta SPACEX_F ; 3
txa ; SPACEX_I was in X ; 2
adc CX_I ; 3
sta SPACEX_I ; 3
;===========
; 16
; temp.i=fixed_sin[angle&0xf].i; // sin()
lda ANGLE ; 3
and #$f ; 2
asl ; 2
tay ; 2
lda fixed_sin,Y ; 4
sta NUM2H ; store for next mul ; 3
; fixed_temp.f=fixed_sin[angle&0xf].f; // sin()
iny ; 2
lda fixed_sin,Y ; 4
sta NUM2L ; store for next mul ; 3
;==========
; 25
;mul6
; fixed_mul(&space_y,&fixed_temp,&space_y);
lda SPACEY_I ; 3
sta NUM1H ; 3
lda SPACEY_F ; 3
sta NUM1L ; 3
; NUM2H:NUM2L already set
sec ; don't reuse previous num1 ; 2
jsr multiply ; 6
; SPACEY_I in X ;
; SPACEY_F in A ;
;==========
; 20
; fixed_add(&space_y,&cy,&space_y);
clc ; 2
; SPACEY_F in A
adc CY_F ; 3
sta SPACEY_F ; 3
txa ; SPACEY_I in X ; 2
adc CY_I ; 3
sta SPACEY_I ; 3
;==========
; 16
; mul7
; fixed_mul(&lowres_half,&dx,&temp);
lda #CONST_LOWRES_HALF_I ; 2
sta NUM1H ; 3
lda #CONST_LOWRES_HALF_F ; 2
sta NUM1L ; 3
lda DX_I ; 3
sta NUM2H ; 3
sta dxi_label+1 ; for self modify ; 4
lda DX_F ; 3
sta dxf_label+1 ; for self modify ; 4
sta NUM2L ; 3
sec ; don't reuse previous num1 ; 2
jsr multiply ; 6
; TEMP_I in X ;
; TEMP_F in A ;
;==========
; 38
; fixed_add(&space_x,&temp,&space_x);
clc ; 2
; TEMP_F in A
adc SPACEX_F ; 3
sta SPACEX_F ; 3
txa ; TEMP_I in X ; 2
adc SPACEX_I ; 3
sta SPACEX_I ; 3
;==========
; 16
;mul8
; fixed_mul(&fixed_temp,&dy,&fixed_temp);
lda DY_I ; 3
sta NUM2H ; 3
sta dyi_label+1 ; for self modify ; 4
lda DY_F ; 3
sta NUM2L ; 3
sta dyf_label+1 ; for self modify ; 4
clc ; reuse CONST_LOWRES_HALF from last time ; 2
jsr multiply ; 6
; TEMP_I in X
; TEMP_F in A
;==========
; 28
; fixed_add(&space_y,&temp,&space_y);
clc ; 2
; TEMP_F in A
adc SPACEY_F ; 3
sta SPACEY_F ; 3
txa ; TEMP_I in X ; 2
adc SPACEY_I ; 3
sta SPACEY_I ; 3
;==========
; 16
ldx #40 ; was SCREEN_X ; 2
;==========
; 2
;===================================================
; SCREEN_X LOOP!!!!
; every cycle in here counts for 32*40=1280 cycles
;===================================================
screenx_loop:
nomatch:
; This is self modified a few times
; jsr lookup_checkerboard_map
; jmp match
; Get color to draw in A
.include "island_lookup.s"
match:
mask_label:
and #0 ; COLOR_MASK (self modifying) ; 2
ldy #0 ; 2
mask_branch_label:
beq big_bottom ; this branch is modified based on odd/even
; F0=beq, D0=bne ; 2nt/3
ora (GBASL),Y ; we're odd, or the bottom in ; 5
big_bottom:
sta (GBASL),Y ; plot double height pixel ; 6
inc GBASL ; point to next pixel ; 5
;============
; 22/18
; advance to the next position in space
; fixed_add(&space_x,&dx,&space_x);
clc ; 2
lda SPACEX_F ; 3
dxf_label:
adc #0 ; self modifying, is DX_F ; 2
sta SPACEX_F ; 3
lda SPACEX_I ; 3
dxi_label:
adc #0 ; self modifying, is DX_I ; 2
sta SPACEX_I ; 3
;==========
; 18
; fixed_add(&space_y,&dy,&space_y);
clc ; 2
lda SPACEY_F ; 3
dyf_label:
adc #0 ; self modifyig, is DY_F ; 2
sta SPACEY_F ; 3
lda SPACEY_I ; 3
dyi_label:
adc #0 ; self mofidying is DY_I ; 2
sta SPACEY_I ; 3
;============
; 18
dex ; decrement SCREEN_X ; 2
beq done_screenx_loop ; branch until we've done 40 ; 2nt/3
;=============
; 4/5
; cache color and return if same as last time
lda SPACEY_I ; 3
spacey_label:
cmp #0 ; self modify, LAST_SPACEY_I ; 2
bne nomatch ; 2nt/3
lda SPACEX_I ; 3
spacex_label:
cmp #0 ; self modify, LAST_SPACEX_I ; 2
bne nomatch ; 2nt/3
map_color_label:
lda #0 ; self modify, LAST_MAP_COLOR ; 2
jmp match ; 3
done_screenx_loop:
inc SCREEN_Y ; 5
lda SCREEN_Y ; 3
cmp #40 ; LOWRES height ; 2
beq done_screeny ; 2nt/3
jmp screeny_loop ; too far to branch ; 3
;=============
; 15
done_screeny:
rts ; 6
;====================
; lookup_map
;====================
; finds value in space_x.i,space_y.i
; returns color in A
; CLOBBERS: A,Y
; this is used to check if above water or grass
; the high-performance per-pixel version has been inlined
lookup_island_map:
.include "island_lookup.s"
rts ; 6
lookup_checkerboard_map:
.include "checkerboard_lookup.s"
rts ; 6
;===============================================
; External modules
;===============================================
.include "gr_putsprite.s"
.include "bg_scroll.s"
.include "sprites.inc"
;===============================================
; Tables
;===============================================
.include "island_map.inc"
.include "starry_sky.scroll"
.include "multiply_fast.s"
; 8.8 fixed point
; should we store as two arrays, one I one F?
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
fixed_sin_scale:
.byte $00,$00
.byte $00,$0c
.byte $00,$16
.byte $00,$1d
.byte $00,$20
.byte $00,$1d
.byte $00,$16
.byte $00,$0c
.byte $00,$00
.byte $ff,$f4
.byte $ff,$ea
.byte $ff,$e3
.byte $ff,$e0
.byte $ff,$e3
.byte $ff,$ea
.byte $ff,$f4
; we can guarantee 4 cycle indexed reads if we page-aligned this
.align 256
horizontal_lookup:
.byte $0C,$0B,$0A,$09,$09,$08,$08,$07,$07,$06,$06,$06,$05,$05,$05,$05
.byte $04,$04,$04,$04,$04,$04,$04,$03,$03,$03,$03,$03,$03,$03,$03,$03
.byte $26,$22,$20,$1D,$1B,$19,$18,$16,$15,$14,$13,$12,$11,$10,$10,$0F
.byte $0E,$0E,$0D,$0D,$0C,$0C,$0C,$0B,$0B,$0A,$0A,$0A,$0A,$09,$09,$09
.byte $40,$3A,$35,$31,$2D,$2A,$28,$25,$23,$21,$20,$1E,$1D,$1B,$1A,$19
.byte $18,$17,$16,$16,$15,$14,$14,$13,$12,$12,$11,$11,$10,$10,$10,$0F
.byte $59,$51,$4A,$44,$40,$3B,$38,$34,$31,$2F,$2C,$2A,$28,$26,$25,$23
.byte $22,$21,$20,$1E,$1D,$1C,$1C,$1B,$1A,$19,$18,$18,$17,$16,$16,$15
.byte $73,$68,$60,$58,$52,$4C,$48,$43,$40,$3C,$39,$36,$34,$32,$30,$2E
.byte $2C,$2A,$29,$27,$26,$25,$24,$22,$21,$20,$20,$1F,$1E,$1D,$1C,$1C
.byte $8C,$80,$75,$6C,$64,$5D,$58,$52,$4E,$4A,$46,$43,$40,$3D,$3A,$38
.byte $36,$34,$32,$30,$2E,$2D,$2C,$2A,$29,$28,$27,$26,$25,$24,$23,$22
.byte $A6,$97,$8A,$80,$76,$6E,$68,$61,$5C,$57,$53,$4F,$4B,$48,$45,$42
.byte $40,$3D,$3B,$39,$37,$35,$34,$32,$30,$2F,$2E,$2C,$2B,$2A,$29,$28
gravity:
; 10fps
; .byte 10,10,10,10,10, 8, 8, 8, 8, 6, 6, 4, 4, 2, 2, 0
; .byte 0, 2, 2, 4, 4, 6, 6, 8, 8, 8, 8,10,10,10,10,10
; 5fps
; .byte 10,10, 8, 8, 6, 4, 2, 0
; .byte 0, 2, 4, 6, 8, 8, 10,10
.byte 10, 8, 8, 6, 6, 4, 2, 0
.byte 0, 2, 4, 6, 6, 8, 8,10
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