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140 lines
3.0 KiB
ArmAsm
140 lines
3.0 KiB
ArmAsm
; Apple II graphics/music in 256B
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; by deater (Vince Weaver) <vince@deater.net>
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; Zero Page
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.include "zp.inc"
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.include "hardware.inc"
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; for a 256 entry we need to fit in 252 bytes
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; 310 bytes -- initial
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; 268 bytes -- strip out interrupts
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; 262 bytes -- simplify init
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; 261 bytes -- optimize init more
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; 253 bytes -- optimize var init
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; 252 bytes -- bne vs jmp
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; 250 bytes -- song only has 16 notes so can never be negative
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; 249 bytes -- make terminating value $80 instead of $FF
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; 247 bytes -- combine note loop. makes song a bit faster
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; 245 bytes -- try to optimize writing out volume
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; 255 bytes -- add in some visualization
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; 252 bytes -- re-arrange decode code
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; 251 bytes -- load in zero page
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; 256 bytes -- expand WAIT to not use jsr
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; 258 bytes -- get rid of pha/pla
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; 255 bytes -- use PLA to load the data after setting stack to 0
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; 249 bytes -- optimize init code to not write 0s to ZP and init $38/$e/$e/$e
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; but instead count on A/B/C over-writing and have the
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; ay buffer over-write the init code
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; 247 bytes -- count on X always being $FF when hit delay
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; 246 bytes -- make SONG_COUNTDOWN self-modify code
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; 241 bytes -- forgot we didn't need to init volume in play_frame anymore
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; 238 bytes -- can use Y to save note value in play_frame now
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; 237 bytes -- make song terminator #$FF so we don't have to load it
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; 235 bytes -- note X is $FF on entry to mockingboard entry
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; 233 bytes -- qkumba noticed we can execute the AY config
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; 252 bytes -- max out visualization
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.zeropage
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;.globalzp frequencies_low
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;.globalzp frequencies_high
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.globalzp colors
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cometsong:
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; we can execute these... (as qkumba noticed)
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; it's SEC, ASL $0E0E
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.byte $38,$e,$e,$e ; mixer, A, B, C volume
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; want to start at AY_REGS+7
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; this is also the start of AY_REGS
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; we count on A/B/C being played first note
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; so the code gets over-written
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; depends on AY ignoring envelope values if unused
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jsr SETGR ; enable lo-res graphics
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; A=$D0, Z=1
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bit FULLGR ; make graphcs full screen
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ldx #$FF ; set stack offset
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txs ; write 0 to stack pointer
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;===================
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; music Player Setup
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tracker_song = peasant_song
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; assume mockingboard in slot#4
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; inline mockingboard_init
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.include "mockingboard_init.s"
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game_loop:
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; typically A=0, X=FF, Y=0 here
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; play a frame of music
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.include "play_frame.s"
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;=================
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;=================
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; visualization?
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;=================
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;=================
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.include "visual.s"
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;==================
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;==================
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; write music to AY registers
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;==================
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;==================
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.include "ay3_write_regs.s"
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;==================
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;==================
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; delay to ~20Hz
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;==================
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;==================
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; X is in theory $ff when we get here
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; delay 20Hz, or 1/20s = 50ms
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; 50,000 cycles
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; 2 + 256*(2+39*5-1) = 49,922
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; ldx #0 ; 2
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outer_wait:
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ldy #39 ; 2
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inner_wait:
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dey ; 2
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bne inner_wait ; 3/2
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dex ; 2
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bne outer_wait ; 3/2
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beq game_loop
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colors:
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.byte 0,9,13,15
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; this needs to start at $80
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; music
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.include "mA2E_2.s"
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.include "notes.inc"
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