118 lines
2.5 KiB
ArmAsm
118 lines
2.5 KiB
ArmAsm
;========================================================================
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; EVERYTHING IS CYCLE COUNTED
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;========================================================================
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;=====================================
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; Set Pattern
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;=====================================
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; set pattern: 11 + 12 + 22 + 22 + 22 + 19 + 18 = 126
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; set_pattern_end: 11 + 16 + ...
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pt3_set_pattern:
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; Lookup current pattern in pattern table
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current_pattern_smc:
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ldy #$d1 ; 2
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lda PT3_LOC+PT3_PATTERN_TABLE,Y ; 4+
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; if value is $FF we are at the end of the song
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cmp #$ff ; 2
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bne not_done_delay_16 ; 3
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;===========
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; 11
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is_done:
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; -1
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; for cycle counted version let's set DONE_SONG
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; but also set to loop forever
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; done with song, set it to non-zero
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sta DONE_SONG ; 3
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ldy PT3_LOC+PT3_LOOP ; 3
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sty current_pattern_smc+1 ; 4
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lda PT3_LOC+PT3_PATTERN_TABLE,Y ; 4+
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jmp not_done ; 3
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;============
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; 16
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not_done_delay_16:
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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nop
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nop
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nop
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not_done:
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; set up the three pattern address pointers
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asl ; mul pattern offset by two, as word sized ; 2
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tay ; 2
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; point PATTERN_H/PATTERN_L to the pattern address table
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clc ; 2
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lda PT3_LOC+PT3_PATTERN_LOC_L ; 4
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sta PATTERN_L ; 3
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lda PT3_LOC+PT3_PATTERN_LOC_H ; 4
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adc #>PT3_LOC ; assume page boundary ; 2
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sta PATTERN_H ; 3
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;===========
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; 22
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; First 16-bits points to the Channel A address
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lda (PATTERN_L),Y ; 5+
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sta note_a+NOTE_ADDR_L ; 3
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iny ; 2
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lda (PATTERN_L),Y ; 5+
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adc #>PT3_LOC ; assume page boundary ; 2
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sta note_a+NOTE_ADDR_H ; 3
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iny ; 2
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;===========
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; 22
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; Next 16-bits points to the Channel B address
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lda (PATTERN_L),Y ; 5+
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sta note_b+NOTE_ADDR_L ; 3
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iny ; 2
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lda (PATTERN_L),Y ; 5+
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adc #>PT3_LOC ; assume page boundary ; 2
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sta note_b+NOTE_ADDR_H ; 3
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iny ; 2
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;===========
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; 22
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; Next 16-bits points to the Channel C address
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lda (PATTERN_L),Y ; 5+
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sta note_c+NOTE_ADDR_L ; 3
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iny ; 2
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lda (PATTERN_L),Y ; 5+
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adc #>PT3_LOC ; assume page boundary ; 2
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sta note_c+NOTE_ADDR_H ; 2
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;===========
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; 19
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; clear out the noise channel
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lda #0 ; 2
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sta pt3_noise_period_smc+1 ; 4
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; Set all three channels as active
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lda #3 ; 2
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sta pt3_pattern_done_smc+1 ; 4
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rts ; 6
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;============
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; 18
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