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chiptune_player: optimize and comment
This commit is contained in:
Vince Weaver
parent
b6e4b5ac8c
commit
d39d531d98
@ -207,7 +207,7 @@ forever_loop:
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; Then it sets up the stack like an interrupt and calls 0x3fe
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interrupt_handler:
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pha ; save A
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pha ; save A ; 3
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; tya
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; pha
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; txa
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@ -216,125 +216,132 @@ interrupt_handler:
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; inc $0404 ; debug
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bit $C404 ; can clear 6522 interrupt by reading T1C-L
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bit $C404 ; clear 6522 interrupt by reading T1C-L ; 4
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;============
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; 7
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;=====================
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; Update time counter
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;=====================
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inc FRAME_COUNT
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lda FRAME_COUNT
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cmp #50
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bne frame_good
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inc FRAME_COUNT ; 5
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lda FRAME_COUNT ; 3
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cmp #50 ; 3
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bne frame_good ; 3/2nt
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lda #$0
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sta FRAME_COUNT
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lda #$0 ; 2
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sta FRAME_COUNT ; 3
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update_second_ones:
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inc $7d0+17
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inc $bd0+17
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lda $bd0+17
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cmp #$ba ; one past '9'
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bne frame_good
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lda #'0'+$80
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sta $7d0+17
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sta $bd0+17
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inc $7d0+17 ; 6
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inc $bd0+17 ; 6
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lda $bd0+17 ; 4
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cmp #$ba ; one past '9' ; 2
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bne frame_good ; 3/2nt
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lda #'0'+$80 ; 2
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sta $7d0+17 ; 4
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sta $bd0+17 ; 4
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update_second_tens:
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inc $7d0+16
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inc $bd0+16
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lda $bd0+16
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cmp #$b6 ; 6
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bne frame_good
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lda #'0'+$80
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sta $7d0+16
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sta $bd0+16
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inc $7d0+16 ; 6
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inc $bd0+16 ; 6
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lda $bd0+16 ; 4
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cmp #$b6 ; 6 (for 60 seconds) ; 2
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bne frame_good ; 3/2nt
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lda #'0'+$80 ; 2
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sta $7d0+16 ; 4
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sta $bd0+16 ; 4
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update_minutes:
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inc $7d0+14
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inc $bd0+14
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; we don't handle > 9:59 songs yet
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inc $7d0+14 ; 6
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inc $bd0+14 ; 6
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; we don't handle > 9:59 songs yet
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;=============
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; 90 worst
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frame_good:
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ldy MB_FRAME_DIFF
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ldy MB_FRAME_DIFF ; get chunk offset ; 3
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ldx #0
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ldx #0 ; set up reg count ; 2
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;=============
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; 5
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mb_write_loop:
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lda (INL),y
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lda (INL),y ; load register value ; 5
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cpx #1
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bne mb_not_one
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cmp #$ff ; if ff, done song
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bne mb_not_one
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; if REG==1 and high bit set
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; then end of song
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lda #1
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sta DONE_PLAYING
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jmp done_interrupt
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bpl mb_not_done ; 3/2nt
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cpx #1 ; 2
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bne mb_not_done ; 3/2nt
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mb_not_one:
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cpx #13
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bne mb_not_13
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cmp #$ff
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beq skip_r13
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lda #1 ; set done playing ; 2
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sta DONE_PLAYING ; 3
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jmp done_interrupt ; 3
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mb_not_done:
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; special case R13. If it is 0xff, then don't update
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; otherwise might spuriously reset the envelope settings
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cpx #13 ; 2
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bne mb_not_13 ; 3/2nt
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cmp #$ff ; 2
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beq skip_r13 ; 3/2nt
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mb_not_13:
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sta MB_VALUE
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sta MB_VALUE ; 3
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cpx #8
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bne mb_not_8
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and #$f
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sta A_VOLUME
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mb_not_8:
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cpx #9
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bne mb_not_9
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and #$f
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sta B_VOLUME
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mb_not_9:
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cpx #10
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bne mb_not_10
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and #$f
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sta C_VOLUME
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mb_not_10:
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; INLINE?
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jsr write_ay_both ; assume 3 channel (not six)
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; so write same to both left/write
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clc
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lda INH
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adc #CHUNKSIZE
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sta INH
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; always write out all to zero page
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; we mostly care about vola/volb/volc so this wastes 11 bytes of RAM
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; code is simpler, and save on three cmp/branches per loop
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inx
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cpx #14
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bmi mb_write_loop
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and #$f ; 2
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sta REGISTER_DUMP,X ; 4
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; INLINE this?
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jsr write_ay_both ; assume 3 channel (not six) ; 6
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; so write same to both
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; left/right
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clc ; point to next interleaved ; 2
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lda INH ; page by adding $300 ; 3
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adc #CHUNKSIZE ; 2
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sta INH ; 3
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inx ; point to next register ; 2
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cpx #14 ; if 14 we're done ; 2
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bmi mb_write_loop ; otherwise, loop ; 3/2nt
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skip_r13:
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lda MB_CHUNK
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clc
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adc #>CHUNK_BUFFER
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sta INH
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lda MB_CHUNK ; reset input pointer ; 3
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clc ; to the beginning ; 2
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adc #>CHUNK_BUFFER ; in proper chunk (1 of 3) ; 2
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sta INH ; 3
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inc MB_FRAME_DIFF
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bne done_interrupt
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inc MB_FRAME_DIFF ; increment offset ; 5
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bne done_interrupt ; if not zero, done ; 3/2nt
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wraparound:
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inc MB_CHUNK
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lda MB_CHUNK
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cmp #CHUNKSIZE
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bne chunk_good
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lda #0
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sta MB_CHUNK
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inc MB_CHUNK ; go to next chunk ; 5
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lda MB_CHUNK ; 3
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cmp #CHUNKSIZE ; have we reached end? ; 2
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bne chunk_good ; 3/2nt
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lda #0 ; if so reset ; 2
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sta MB_CHUNK ; 3
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jsr next_subsong
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; can't tail call as need to restore stack and rti
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jsr next_subsong ; and decompress next ; 6
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chunk_good:
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done_interrupt:
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pla
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; tax
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; pla
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; tay
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; pla
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rti
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pla ; restore a ; 4
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rti ; 6
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;=================
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@ -493,11 +500,13 @@ bloop22:
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; filenames
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;==========
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krw_file:
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.asciiz "INTRO2.KRW"
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.asciiz "CRMOROS.KRW"
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.asciiz "CHRISTMAS.KRW"
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.asciiz "CAMOUFLAGE.KRW"
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.asciiz "FIGHTING.KRW"
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.asciiz "UNIVERSE.KRW"
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.asciiz "INTRO2.KRW"
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.asciiz "TECHNO.KRW"
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;=========
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