dos33fsprogs/interlace_demo/pt3_lib_do_frame.s

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