100 lines
1.9 KiB
NASM
100 lines
1.9 KiB
NASM
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********************************
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*
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* MUSIC SUBROUTINE
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*
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* GARY J. SHANNON
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*
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********************************
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ORG $D717
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*
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* ZERO PAGE WORK AREAS
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* PARAMETER PASSING AREAS
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*
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DOWNTIME EQU $0
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UPTIME EQU $1
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LENGTH EQU $2
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VOICE EQU $2FD
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LONG EQU $2FE
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NOTE EQU $2FF
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SPEAKER EQU $C030
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ENTRY JMP LOOKUP
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PLAY LDY UPTIME
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LDA SPEAKER
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PLAY2 INC LENGTH
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BNE PATH1
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INC LENGTH+1
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BNE PATH2
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RTS
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PATH1 NOP
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JMP PATH2
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PATH2 DEY
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BEQ DOWN
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JMP PATH3
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PATH3 BNE PLAY2
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DOWN LDY DOWNTIME
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LDA SPEAKER
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PLAY3 INC LENGTH
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BNE PATH4
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INC LENGTH+1
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BNE PATH5
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RTS
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PATH4 NOP
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JMP PATH5
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PATH5 DEY
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BEQ PLAY
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JMP PATH6
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PATH6 BNE PLAY3
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LOOKUP LDA NOTE
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ASL
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TAY
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LDA NOTES,Y
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STA DOWNTIME
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LDA VOICE
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SHIFT LSR
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BEQ DONE
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LSR DOWNTIME
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BNE SHIFT
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DONE LDA NOTES,Y
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SEC
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SBC DOWNTIME
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STA UPTIME
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INY
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LDA NOTES,Y
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ADC DOWNTIME
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STA DOWNTIME
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LDA #$0
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SEC
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SBC LONG
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STA LENGTH+1
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LDA #$0
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STA LENGTH
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LDA UPTIME
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BNE PLAY
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REST NOP
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NOP
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JMP REST2
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REST2 INC LENGTH
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BNE REST3
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INC LENGTH+1
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BNE REST4
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RTS
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REST3 NOP
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JMP REST4
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REST4 BNE REST
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NOTES HEX 00,00,F6,F6,E8,E8,DB,DB
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HEX CF,CF,C3,C3,B8,B8,AE,AE
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HEX A4,A4,9B,9B,92,92,8A,8A
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HEX 82,82,7B,7B,74,74,6D,6E
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HEX 67,68,61,62,5C,5C,57,57
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HEX 52,52,4D,4E,49,49,45,45
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HEX 41,41,3D,3E,3A,3A,36,37
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HEX 33,34,30,31,2E,2E,2B,2C
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HEX 29,29,26,27,24,25,22,23
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HEX 20,21,1E,1F,1D,1D,1B,1C
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HEX 1A,1A,18,19,17,17,15,16
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HEX 14,15,13,14,12,12,11,11
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HEX 10,10,0F,10,0E,0F
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