210 lines
4.6 KiB
ArmAsm
210 lines
4.6 KiB
ArmAsm
;========================================================================
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; EVERYTHING IS CYCLE COUNTED
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;========================================================================
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;======================================
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; do frame
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;======================================
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; ????? FIXME/calculate note
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;
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; 9+ 202 + 36+11+18+30+18+49 = 373
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do_frame:
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; AY-3-8910 register summary
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;
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; R0/R1 = A period low/high
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; R2/R3 = B period low/high
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; R4/R5 = C period low/high
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; R6 = Noise period
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; R7 = Enable XX Noise=!CBA Tone=!CBA
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; R8/R9/R10 = Channel A/B/C amplitude M3210, M=envelope enable
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; R11/R12 = Envelope Period low/high
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; R13 = Envelope Shape, 0xff means don't write
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; R14/R15 = I/O (ignored)
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ldx #0 ; needed ; 2
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stx PT3_MIXER_VAL ; 3
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stx pt3_envelope_add_smc+1 ; 4
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;===========
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; 9
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;;ldx #(NOTE_STRUCT_SIZE*0) ; Note A
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jsr calculate_note ; 6+60
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ldx #(NOTE_STRUCT_SIZE*1) ; Note B ; 2
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jsr calculate_note ; 6+60
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ldx #(NOTE_STRUCT_SIZE*2) ; Note C ; 2
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jsr calculate_note ; 6+60
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;=============
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; 202
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; Note, we assume 1MHz timings, adjust pt3 as needed
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; Load up the Frequency Registers
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lda note_a+NOTE_TONE_L ; Note A Period L (ZP) ; 3
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sta AY_REGISTERS+0 ; into R0 ; 3
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lda note_a+NOTE_TONE_H ; Note A Period H ; 3
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sta AY_REGISTERS+1 ; into R1 ; 3
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lda note_b+NOTE_TONE_L ; Note B Period L ; 3
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sta AY_REGISTERS+2 ; into R2 ; 3
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lda note_b+NOTE_TONE_H ; Note B Period H ; 3
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sta AY_REGISTERS+3 ; into R3 ; 3
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lda note_c+NOTE_TONE_L ; Note C Period L ; 3
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sta AY_REGISTERS+4 ; into R4 ; 3
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lda note_c+NOTE_TONE_H ; Note C Period H ; 3
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sta AY_REGISTERS+5 ; into R5 ; 3
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;===========
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; 36
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; Noise
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; frame[6]= (pt3->noise_period+pt3->noise_add)&0x1f;
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clc ; 2
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pt3_noise_period_smc:
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lda #$d1 ; 2
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pt3_noise_add_smc:
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adc #$d1 ; 2
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and #$1f ; 2
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sta AY_REGISTERS+6 ; 3
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;============
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; 11
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;=======================
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; Mixer
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; PT3_MIXER_VAL is already in AY_REGISTERS+7
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;=======================
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; Amplitudes
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lda note_a+NOTE_AMPLITUDE ; 3
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sta AY_REGISTERS+8 ; 3
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lda note_b+NOTE_AMPLITUDE ; 3
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sta AY_REGISTERS+9 ; 3
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lda note_c+NOTE_AMPLITUDE ; 3
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sta AY_REGISTERS+10 ; 3
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;===========
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; 18
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;======================================
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; Envelope period
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; result=period+add+slide (16-bits)
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clc ; 2
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pt3_envelope_period_l_smc:
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lda #$d1 ; 2
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pt3_envelope_add_smc:
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adc #$d1 ; 2
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tay ; 2
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pt3_envelope_period_h_smc:
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lda #$d1 ; 2
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adc #0 ; 2
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tax ; 2
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clc ; 2
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tya ; 2
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pt3_envelope_slide_l_smc:
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adc #$d1 ; 2
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sta AY_REGISTERS+11 ; 3
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txa ; 2
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pt3_envelope_slide_h_smc:
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adc #$d1 ; 2
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sta AY_REGISTERS+12 ; 3
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;===========
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; 30
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;========================
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; Envelope shape
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; same=11 + 7 = 18
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; diff=11 + [4] + 3 = 18
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pt3_envelope_type_smc:
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lda #$d1 ; 2
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pt3_envelope_type_old_smc:
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cmp #$d1 ; 2
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sta pt3_envelope_type_old_smc+1; copy old to new ; 4
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bne envelope_diff_waste ; 3
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;============
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; 11
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envelope_same:
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;-1
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lda #$ff ; if same, store $ff ; 2
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jmp envelope_diff ; 3
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envelope_diff_waste:
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nop ; 2
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nop ; 2
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envelope_diff:
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sta AY_REGISTERS+13 ; 3
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;============
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; 18
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;==============================
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; end-of-frame envelope update
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;==============================
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; if envelope delay 0, skip
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; = 5+ [38] + 6 = 49
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; else if envelope delay 1, skip
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; = 5+8+[30] + 6 = 49
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; else
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; = 5+8+30+6 = 49
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pt3_envelope_delay_smc:
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lda #$d1 ; 2
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beq done_do_frame_x ; assume can't be negative? ; 3
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; do this if envelope_delay>0
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;==========
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; 5
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; -1
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dec pt3_envelope_delay_smc+1 ; 6
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bne done_do_frame_y ; 3
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;==========
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; 8
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; only do if we hit 0
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; -1
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pt3_envelope_delay_orig_smc:
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lda #$d1 ; reset envelope delay ; 2
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sta pt3_envelope_delay_smc+1 ; 4
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clc ; 16-bit add ; 2
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lda pt3_envelope_slide_l_smc+1 ; 4
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pt3_envelope_slide_add_l_smc:
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adc #$d1 ; 2
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sta pt3_envelope_slide_l_smc+1 ; 4
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lda pt3_envelope_slide_h_smc+1 ; 4
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pt3_envelope_slide_add_h_smc:
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adc #$d1 ; 2
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sta pt3_envelope_slide_h_smc+1 ; 4
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jmp done_do_frame ; 3
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;===========
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; 30
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done_do_frame_x:
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; waste 8
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nop ; 2
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nop ; 2
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nop ; 2
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nop ; 2
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done_do_frame_y:
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; waste 30
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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inc CYCLE_WASTE ; 5
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done_do_frame:
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rts ; 6
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