560 lines
9.2 KiB
NASM
560 lines
9.2 KiB
NASM
!cpu 6510
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; Fireworks - an animated PETSCII fireworks simulator with SID effects.
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; Self-starting BASIC line: 10 SYS2061
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* = $0801
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!word basic_end
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!word 10
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!byte $9e
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!text "2061"
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!byte 0
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basic_end: !word 0
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* = $080d
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SCREEN = $0400
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COLOR = $d800
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GETIN = $ffe4
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CHROUT = $ffd2
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start:
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lda $d020
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sta old_border
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lda $d021
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sta old_background
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lda $d418
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sta old_volume
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ldx #0
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save_sid:
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lda $d400,x
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sta old_sid,x
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inx
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cpx #7
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bne save_sid
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lda #0
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sta $d020
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sta $d021
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jsr show_splash
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lda #147
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jsr CHROUT
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lda #0
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sta $d020
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sta $d021
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sta show_state
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sta palette
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sta auto_show
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sta tick
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sta seed
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lda #3
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sta animation_speed
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lda #18
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sta auto_countdown
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lda $a2
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sta last_jiffy
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jsr draw_skyline
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jsr draw_stars
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main_loop:
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jsr GETIN
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beq check_clock
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cmp #81
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bne check_launch
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jmp exit
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check_launch:
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cmp #32
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bne check_auto
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jsr launch_rocket
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jmp check_clock
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check_auto:
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cmp #65
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bne check_color
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lda auto_show
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eor #1
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sta auto_show
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lda #4
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sta auto_countdown
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jmp check_clock
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check_color:
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cmp #67
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bne check_speed_one
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inc palette
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lda palette
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and #3
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sta palette
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jmp check_clock
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check_speed_one:
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cmp #49
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bne check_speed_two
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lda #6
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sta animation_speed
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jmp check_clock
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check_speed_two:
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cmp #50
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bne check_speed_three
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lda #3
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sta animation_speed
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jmp check_clock
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check_speed_three:
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cmp #51
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bne check_clock
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lda #1
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sta animation_speed
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check_clock:
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lda $a2
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cmp last_jiffy
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beq main_loop
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sta last_jiffy
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inc tick
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lda tick
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cmp animation_speed
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bcc main_loop
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lda #0
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sta tick
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inc seed
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jsr twinkle_star
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lda show_state
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beq idle_frame
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cmp #1
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bne dispatch_explosion
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jsr update_rocket
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jmp main_loop
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dispatch_explosion:
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jsr update_explosion
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jmp main_loop
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idle_frame:
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lda auto_show
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bne auto_active
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jmp main_loop
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auto_active:
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dec auto_countdown
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beq auto_launch
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jmp main_loop
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auto_launch:
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jsr launch_rocket
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jmp main_loop
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launch_rocket:
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lda show_state
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bne launch_done
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lda seed
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clc
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adc $d012
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and #31
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cmp #24
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bcc center_ready
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sbc #24
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center_ready:
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clc
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adc #8
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sta center_x
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sta rocket_x
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lda #20
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sta rocket_y
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lda #1
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sta show_state
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lda #2
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sta trail_length
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jsr rocket_sound
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launch_done:
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rts
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update_rocket:
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; Erase the oldest trail cell.
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lda rocket_x
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sta plot_x
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lda rocket_y
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clc
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adc #2
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cmp #20
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bcs skip_old_trail
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sta plot_y
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lda #32
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ldy #0
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jsr plot_character
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skip_old_trail:
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; Turn the old rocket position into a fading trail.
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lda rocket_y
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sta plot_y
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lda #46
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ldy #7
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jsr plot_character
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dec rocket_y
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lda rocket_y
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cmp #6
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bne draw_rocket
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lda rocket_x
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sta plot_x
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lda #32
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ldy #0
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jsr plot_character
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lda #2
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sta show_state
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lda #0
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sta explosion_stage
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jsr explosion_sound
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jsr draw_explosion
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rts
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draw_rocket:
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sta plot_y
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lda rocket_x
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sta plot_x
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lda #94
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ldy #1
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jsr plot_character
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jsr rocket_sound
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rts
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update_explosion:
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jsr erase_explosion
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inc explosion_stage
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lda explosion_stage
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cmp #5
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bcs finish_explosion
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jsr explosion_sound
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jsr draw_explosion
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rts
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finish_explosion:
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lda #0
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sta show_state
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lda seed
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and #15
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clc
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adc #8
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sta auto_countdown
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jsr silence_sid
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jsr draw_skyline
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jsr draw_stars
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rts
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draw_explosion:
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lda #0
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sta particle
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draw_particle_loop:
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jsr select_particle_position
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lda explosion_stage
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tax
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lda burst_chars,x
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ldx particle
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ldy particle_colors,x
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ldx palette
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beq color_ready
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palette_shift_loop:
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tya
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clc
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adc #3
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and #15
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tay
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dex
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bne palette_shift_loop
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color_ready:
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jsr plot_character
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inc particle
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lda particle
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cmp #16
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bne draw_particle_loop
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rts
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erase_explosion:
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lda #0
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sta particle
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erase_particle_loop:
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jsr select_particle_position
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lda #32
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ldy #0
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jsr plot_character
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inc particle
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lda particle
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cmp #16
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bne erase_particle_loop
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rts
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select_particle_position:
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lda explosion_stage
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asl
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asl
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asl
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asl
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clc
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adc particle
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tax
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lda burst_dx,x
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clc
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adc center_x
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sta plot_x
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lda burst_dy,x
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clc
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adc #6
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sta plot_y
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rts
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draw_stars:
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ldx #0
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star_loop:
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stx object_index
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lda star_x,x
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sta plot_x
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lda star_y,x
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sta plot_y
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txa
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and #1
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beq star_dot
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lda #42
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bne paint_star
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star_dot:
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lda #46
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paint_star:
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ldy #15
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jsr plot_character
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ldx object_index
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inx
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cpx #18
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bne star_loop
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rts
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twinkle_star:
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lda seed
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and #15
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tax
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stx object_index
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lda star_x,x
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sta plot_x
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lda star_y,x
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sta plot_y
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lda seed
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and #1
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beq twinkle_dot
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lda #42
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bne twinkle_paint
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twinkle_dot:
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lda #46
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twinkle_paint:
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ldy #1
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jsr plot_character
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rts
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draw_skyline:
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ldx #0
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building_loop:
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stx plot_x
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lda building_height,x
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sta height_left
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lda #24
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sta plot_y
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building_column:
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lda #160
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ldy #11
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jsr plot_character
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dec plot_y
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dec height_left
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bne building_column
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inx
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cpx #40
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bne building_loop
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; Warm windows across the skyline.
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ldx #0
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window_loop:
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stx object_index
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lda window_x,x
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sta plot_x
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lda window_y,x
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sta plot_y
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lda #81
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ldy #7
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jsr plot_character
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ldx object_index
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inx
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cpx #12
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bne window_loop
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rts
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rocket_sound:
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lda rocket_y
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eor #$ff
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sta $d400
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lda #22
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sta $d401
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lda #$11
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sta $d404
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lda #$0f
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sta $d418
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rts
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explosion_sound:
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lda #0
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sta $d400
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lda #45
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sta $d401
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lda #$81
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sta $d404
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lda #$08
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sta $d405
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lda #$88
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sta $d406
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lda #$0f
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sta $d418
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rts
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silence_sid:
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lda #0
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sta $d404
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sta $d418
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rts
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plot_character:
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sta character
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sty character_color
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ldy plot_y
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lda screen_row_lo,y
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sta $fb
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lda screen_row_hi,y
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sta $fc
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lda color_row_lo,y
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sta $fd
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lda color_row_hi,y
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sta $fe
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ldy plot_x
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lda character
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sta ($fb),y
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lda character_color
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sta ($fd),y
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rts
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show_splash:
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lda #<splash_text
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sta $fb
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lda #>splash_text
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sta $fc
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ldy #0
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print_splash:
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lda ($fb),y
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beq wait_for_space
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jsr CHROUT
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inc $fb
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bne print_splash
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inc $fc
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jmp print_splash
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wait_for_space:
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jsr GETIN
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cmp #32
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bne wait_for_space
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rts
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exit:
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jsr silence_sid
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ldx #0
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restore_sid:
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lda old_sid,x
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sta $d400,x
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inx
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cpx #7
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bne restore_sid
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lda old_volume
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sta $d418
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lda old_border
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sta $d020
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lda old_background
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sta $d021
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lda #147
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jsr CHROUT
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rts
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splash_text:
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!byte 147,13,13,13
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!byte 154
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!text " FIREWORKS"
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!byte 13,13
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!byte 5
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!text " A PETSCII SKY FULL OF COLOR AND SOUND"
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!byte 13,13,13
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!byte 153
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!text " CONTROLS"
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!byte 13,13
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!text " "
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!byte 158
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!text "SPACE"
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!byte 5
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!text " LAUNCH "
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!byte 158
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!text "A"
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!byte 5
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!text " AUTO "
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!byte 158
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!text "C"
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!byte 5
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!text " COLOR"
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!byte 13
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!text " "
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!byte 158
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!text "1-3"
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!byte 5
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!text " SPEED "
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!byte 158
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!text "Q"
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!byte 5
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!text " QUIT"
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!byte 13,13,13
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!byte 5
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!text " HTTPS://C64.P20.DEV"
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!byte 13,13
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!byte 152
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!text " RELEASED 16 OCTOBER 2026"
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!byte 13,13,13
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!byte 158
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!text " PRESS SPACE TO START"
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!byte 0
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; Five expansion stages, sixteen points per stage. Signed offsets are stored
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; as bytes; normal 6502 wrapping performs the addition around the burst center.
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burst_dx:
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!byte 0,1,1,1,0,$ff,$ff,$ff,0,1,0,$ff,1,1,$ff,$ff
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!byte 0,1,2,1,0,$ff,$fe,$ff,2,2,0,$fe,1,1,$ff,$ff
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!byte 0,2,3,2,0,$fe,$fd,$fe,3,3,0,$fd,1,1,$ff,$ff
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!byte 0,2,4,2,0,$fe,$fc,$fe,4,3,0,$fc,1,1,$ff,$ff
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!byte 0,3,5,3,0,$fd,$fb,$fd,5,4,0,$fb,2,2,$fe,$fe
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burst_dy:
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!byte $ff,$ff,0,1,1,1,0,$ff,$ff,0,1,0,$ff,1,1,$ff
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!byte $fe,$ff,0,1,2,1,0,$ff,$fe,0,2,0,$ff,1,1,$ff
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!byte $fd,$fe,0,2,3,2,0,$fe,$fd,0,3,0,$ff,1,1,$ff
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!byte $fc,$fe,0,2,4,2,0,$fe,$fc,0,4,0,$ff,1,1,$ff
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!byte $fb,$fd,0,3,5,3,0,$fd,$fb,0,5,0,$fe,2,2,$fe
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burst_chars: !byte 81,42,43,46,46
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particle_colors: !byte 1,7,10,8,2,5,3,13,1,7,10,8,2,5,3,13
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star_x: !byte 2,5,8,11,14,17,20,23,26,29,32,35,38,4,10,27,34,16
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star_y: !byte 3,8,5,12,4,9,3,13,6,10,4,8,12,15,17,16,14,6
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building_height:
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!byte 3,3,4,4,4,6,6,6,5,5,3,3,7,7,7,7,4,4,5,5
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!byte 5,8,8,8,6,6,4,4,4,7,7,7,5,5,6,6,6,3,3,3
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window_x: !byte 2,6,9,13,16,19,22,25,29,32,35,38
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window_y: !byte 23,21,22,20,23,22,19,21,20,22,21,23
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screen_row_lo: !for i,0,24 { !byte <(SCREEN+i*40) }
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screen_row_hi: !for i,0,24 { !byte >(SCREEN+i*40) }
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color_row_lo: !for i,0,24 { !byte <(COLOR+i*40) }
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color_row_hi: !for i,0,24 { !byte >(COLOR+i*40) }
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show_state: !byte 0
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palette: !byte 0
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auto_show: !byte 0
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auto_countdown: !byte 0
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animation_speed: !byte 0
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tick: !byte 0
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last_jiffy: !byte 0
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seed: !byte 0
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center_x: !byte 0
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rocket_x: !byte 0
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rocket_y: !byte 0
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trail_length: !byte 0
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explosion_stage: !byte 0
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particle: !byte 0
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plot_x: !byte 0
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plot_y: !byte 0
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character: !byte 0
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character_color: !byte 0
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height_left: !byte 0
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object_index: !byte 0
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old_border: !byte 0
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old_background: !byte 0
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old_volume: !byte 0
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old_sid: !fill 7,0
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