dos33fsprogs/interlace_demo/pt3_lib_decode_note.s

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;========================================================================
; EVERYTHING IS CYCLE COUNTED
;========================================================================
;=====================================
; Decode Note
;=====================================
; X points to the note offset
; Note! These timings are out of date (FIXME)
; Timings (from ===>)
; 00: 14+30
; 0X: 14+15
; 10: 14+5 +124
; 1X: 14+5 +193
; 2X/3X: 14+5 +17
; 4X: 14+5+5 + 111
; 5X-BX: 14+5+5+ 102
; CX:
; DX/EX:
; FX:
stop_decoding:
; we are still running, decrement and early return
dec note_a+NOTE_LEN_COUNT,X ; 7
rts ; 6
;=====================================
; Decode Line
;=====================================
pt3_decode_line:
; decode_note(&pt3->a,&(pt3->a_addr),pt3);
ldx #(NOTE_STRUCT_SIZE*0) ; 2
jsr decode_note ; 6+??
; decode_note(&pt3->b,&(pt3->b_addr),pt3);
ldx #(NOTE_STRUCT_SIZE*1) ; 2
jsr decode_note ; 6+??
; decode_note(&pt3->c,&(pt3->c_addr),pt3);
ldx #(NOTE_STRUCT_SIZE*2) ; 2
;;jsr decode_note ; fall through
; if (pt3->a.all_done && pt3->b.all_done && pt3->c.all_done) {
; return 1;
; }
;=================================
;=================================
; decode note
;=================================
;=================================
decode_note:
; Init vars
ldy #0 ; 2
sty spec_command_smc+1 ; 4
; Skip decode if note still running
lda note_a+NOTE_LEN_COUNT,X ; 4
cmp #2 ; 2
bcs stop_decoding ; blt, assume not negative ; 3
; -1
keep_decoding:
lda note_a+NOTE_NOTE,X ; store prev note ; 4
sta prev_note_smc+1 ; 4
lda note_a+NOTE_TONE_SLIDING_H,X ; store prev sliding ; 4
sta prev_sliding_h_smc+1 ; 4
lda note_a+NOTE_TONE_SLIDING_L,X ; 4
sta prev_sliding_l_smc+1 ; 4
note_decode_loop:
lda note_a+NOTE_LEN,X ; re-up length count ; 4
sta note_a+NOTE_LEN_COUNT,X ; 4
lda note_a+NOTE_ADDR_L,X ; 4
sta PATTERN_L ; 3
lda note_a+NOTE_ADDR_H,X ; 4
sta PATTERN_H ; 3
; get next value
lda (PATTERN_L),Y ; 5
sta note_command_smc+1 ; save termporarily ; 4
and #$0f ; 2
sta note_command_bottom_smc+1 ; 4
note_command_smc:
lda #$d1 ; 2
; Set up jump table that runs same speed on 6502 and 65c02
sty PT3_TEMP ; 3
and #$f0 ; 2
lsr ; 2
lsr ; 2
lsr ; 2
tay ; 2
lda decode_jump_table+1,y ; 4
pha ; 3
lda decode_jump_table,y ; 4
pha ; 3
ldy PT3_TEMP ; 3
rts ; 6
;=============
; 23
decode_jump_table:
.word decode_case_0X-1,decode_case_1X-1,decode_case_2X-1
.word decode_case_3X-1,decode_case_4X-1,decode_case_5X-1
.word decode_case_6X-1,decode_case_7X-1,decode_case_8X-1
.word decode_case_9X-1,decode_case_AX-1,decode_case_BX-1
.word decode_case_CX-1,decode_case_DX-1,decode_case_EX-1
.word decode_case_FX-1
decode_case_0X:
;==============================
; $0X set special effect
;==============================
note_command_bottom_smc:
lda #$d1 ; 2
; we can always store spec as 0 means no spec
; FIXME: what if multiple spec commands?
; Doesn't seem to happen in practice
; But AY_emul has code to handle it
sta spec_command_smc+1 ; 4
bne decode_case_0X_not_zero ; 2/3
;=============
; 8
; 00 case
; means end of pattern
; -1
sta note_a+NOTE_LEN_COUNT,X ; len_count=0; ; 4
dec pt3_pattern_done_smc+1 ; 6
jmp note_done_decoding ; 3
decode_case_1X:
;==============================
; $1X -- Set Envelope Type
;==============================
lda note_command_bottom_smc+1 ; 4
bne decode_case_not_10 ; 3
decode_case_10:
; 10 case - disable ; -1
sta note_a+NOTE_ENVELOPE_ENABLED,X ; A is 0 ; 5
beq decode_case_1x_common ; branch always ; 3
decode_case_not_10:
; -1
jsr set_envelope ; 6+64
decode_case_1x_common:
iny ; 2
lda (PATTERN_L),Y ; 5+
lsr ; 2
jsr load_sample ; 6+86
lda #0 ; 2
sta note_a+NOTE_ORNAMENT_POSITION,X ; ornament_position=0 ; 5
decode_case_0X_not_zero:
jmp done_decode_loop ; 3
decode_case_2X:
decode_case_3X:
;==============================
; $2X/$3X set noise period
;==============================
lda note_command_smc+1 ; 4
adc #$e0 ; same as subtract $20 ; 2
sta pt3_noise_period_smc+1 ; 3
jmp done_decode_loop ; 3
;===========
; 16
decode_case_4X:
;==============================
; $4X -- set ornament
;==============================
lda note_command_bottom_smc+1; set ornament to bottom nibble; 4
jsr load_ornament ; 6+93
jmp done_decode_loop ; 3
;============
; 110
decode_case_5X:
decode_case_6X:
decode_case_7X:
decode_case_8X:
decode_case_9X:
decode_case_AX:
;==============================
; $5X-$AX set note
;==============================
lda note_command_smc+1 ; 4
adc #$b0 ; 2
sta note_a+NOTE_NOTE,X ; note=(current_val-0x50); ; 5
jsr reset_note ; 6+69
lda #1 ; 2
sta note_a+NOTE_ENABLED,X ; enabled=1 ; 5
bne note_done_decoding ; 3
decode_case_BX:
;============================================
; $BX -- note length or envelope manipulation
;============================================
lda note_command_bottom_smc+1 ; 4
beq decode_case_b0 ; 3
; -1
sec
sbc #1 ; envelope_type=(current_val&0xf)-1; ; 2
bne decode_case_bx_higher ; 3
decode_case_b1:
; Set Length
; get next byte
iny ; 2
lda (PATTERN_L),Y ; 5
sta note_a+NOTE_LEN,X ; 5
sta note_a+NOTE_LEN_COUNT,X ; 5
bcs done_decode_loop ; branch always ; 3
decode_case_b0:
; Disable envelope
sta note_a+NOTE_ENVELOPE_ENABLED,X ; 5
sta note_a+NOTE_ORNAMENT_POSITION,X ; 5
beq done_decode_loop ; 3
decode_case_bx_higher:
jsr set_envelope ; 6+64
bcs done_decode_loop ; branch always ; 3
decode_case_CX:
;==============================
; $CX -- set volume
;==============================
lda note_command_bottom_smc+1 ; 4
bne decode_case_cx_not_c0 ; 3
; -1
decode_case_c0:
; special case $C0 means shut down the note
sta note_a+NOTE_ENABLED,X ; enabled=0 ; 5
jsr reset_note ; 6+69
beq note_done_decoding ; branch always ; 3
decode_case_cx_not_c0:
sta note_a+NOTE_VOLUME,X ; volume=current_val&0xf; 5
bne done_decode_loop ; branch always ; 3
decode_case_DX:
decode_case_EX:
;==============================
; $DX/$EX -- change sample
;==============================
; D0 = special case (end note)
; D1-EF = set sample to (value - $D0)
lda note_command_smc+1 ; 4
sec ; 2
sbc #$d0 ; 2
beq note_done_decoding ; 3
decode_case_not_d0:
; -1
jsr load_sample ; load sample in bottom nybble ; 6+??
bcc done_decode_loop; branch always ; 3
;========================
; d0 case means end note
;decode_case_d0:
; jmp note_done_decoding
;==============================
; $FX - change ornament/sample
;==============================
decode_case_FX:
; disable envelope
lda #0 ; 2
sta note_a+NOTE_ENVELOPE_ENABLED,X ; 5
; Set ornament to low byte of command
lda note_command_bottom_smc+1 ; 4
jsr load_ornament ; ornament to load in A ; 6+?
; Get next byte
iny ; point to next byte ; 2
lda (PATTERN_L),Y ; 5
; Set sample to value/2
lsr ; divide by two ; 2
jsr load_sample ; sample to load in A ; 6+?
; fallthrough
done_decode_loop:
iny ; point to next byte ; 2
jmp note_decode_loop ; 3
note_done_decoding:
iny ; point to next byte ; 2
;=================================
; handle effects
;=================================
; Note, the AYemul code has code to make sure these are applied
; In the same order they appear. We don't bother?
handle_effects:
spec_command_smc:
lda #$d1 ; 2
;==============================
; Effect #1 -- Tone Down
;==============================
effect_1:
cmp #$1 ; 2
bne effect_2 ; 3
; -1
sta note_a+NOTE_SIMPLE_GLISS,X ; 5
lsr ; 2
sta note_a+NOTE_ONOFF,X ; 5
lda (PATTERN_L),Y ; load byte, set as slide delay ; 5
iny ; 2
sta note_a+NOTE_TONE_SLIDE_DELAY,X ; 5
sta note_a+NOTE_TONE_SLIDE_COUNT,X ; 5
lda (PATTERN_L),Y ; load byte, set as slide step low ; 5
iny ; 2
sta note_a+NOTE_TONE_SLIDE_STEP_L,X ; 5
lda (PATTERN_L),Y ; load byte, set as slide step high ; 5
iny ; 2
sta note_a+NOTE_TONE_SLIDE_STEP_H,X ; 5
jmp no_effect ; 3
;==============================
; Effect #2 -- Portamento
;==============================
effect_2:
cmp #$2 ; 2
beq effect_2_small ; 3
; -1
jmp effect_3 ; 3
effect_2_small: ; FIXME: make smaller
lda #0 ; 2
sta note_a+NOTE_SIMPLE_GLISS,X ; 5
sta note_a+NOTE_ONOFF,X ; 5
lda (PATTERN_L),Y ; load byte, set as delay ; 5
iny ; 2
sta note_a+NOTE_TONE_SLIDE_DELAY,X ; 5
sta note_a+NOTE_TONE_SLIDE_COUNT,X ; 5
iny ; 2
iny ; 2
iny ; 2
lda (PATTERN_L),Y ; load byte, set as slide_step high ; 5
php ; 3
; 16-bit absolute value
bpl slide_step_positive1 ; 3
;-1
eor #$ff ; 2
slide_step_positive1:
sta note_a+NOTE_TONE_SLIDE_STEP_H,X ; 5
dey ; 2
lda (PATTERN_L),Y ; load byte, set as slide_step low ; 5
plp ; 4
clc ; 2
bpl slide_step_positive2 ; 3
;-1
eor #$ff ; 2
sec ; 2
slide_step_positive2:
adc #$0 ; 2
sta note_a+NOTE_TONE_SLIDE_STEP_L,X ; 5
bcc skip_step_inc1 ; 3
inc note_a+NOTE_TONE_SLIDE_STEP_H,X ; 7
skip_step_inc1:
iny ; moved here as it messed with flags ; 2
iny ; 2
; a->tone_delta=GetNoteFreq(a->note,pt3)-
; GetNoteFreq(prev_note,pt3);
sty PT3_TEMP ; save Y
prev_note_smc:
ldy #$d1
lda NoteTable_low,Y ; GetNoteFreq
sta temp_word_l2_smc+1
lda NoteTable_high,Y ; GetNoteFreq
sta temp_word_h2_smc+1
ldy note_a+NOTE_NOTE,X
lda NoteTable_low,Y ; GetNoteFreq
sec
temp_word_l2_smc:
sbc #$d1
sta note_a+NOTE_TONE_DELTA_L,X
lda NoteTable_high,Y ; GetNoteFreq
temp_word_h2_smc:
sbc #$d1
sta note_a+NOTE_TONE_DELTA_H,X
; a->slide_to_note=a->note;
lda note_a+NOTE_NOTE,X
sta note_a+NOTE_SLIDE_TO_NOTE,X
ldy PT3_TEMP ; restore Y
; a->note=prev_note;
lda prev_note_smc+1
sta note_a+NOTE_NOTE,X
; implement file version 6 and above slide behavior
; this is done by SMC at song init time
version_smc:
jmp weird_version ; (JMP to BIT via smc) ; 3
prev_sliding_l_smc:
lda #$d1
sta note_a+NOTE_TONE_SLIDING_L,X
prev_sliding_h_smc:
lda #$d1
sta note_a+NOTE_TONE_SLIDING_H,X
weird_version:
; annoying 16-bit subtract, only care if negative
; if ((a->tone_delta - a->tone_sliding) < 0) {
sec
lda note_a+NOTE_TONE_DELTA_L,X
sbc note_a+NOTE_TONE_SLIDING_L,X
lda note_a+NOTE_TONE_DELTA_H,X
sbc note_a+NOTE_TONE_SLIDING_H,X
bpl no_effect
; a->tone_slide_step = -a->tone_slide_step;
lda note_a+NOTE_TONE_SLIDE_STEP_L,X
eor #$ff
clc
adc #$1
sta note_a+NOTE_TONE_SLIDE_STEP_L,X
lda note_a+NOTE_TONE_SLIDE_STEP_H,X
eor #$ff
adc #$0
sta note_a+NOTE_TONE_SLIDE_STEP_H,X
jmp no_effect
;==============================
; Effect #3 -- Sample Position
;==============================
effect_3:
cmp #$3
bne effect_4
lda (PATTERN_L),Y ; load byte, set as sample position
iny
sta note_a+NOTE_SAMPLE_POSITION,X
bne no_effect ; branch always
;==============================
; Effect #4 -- Ornament Position
;==============================
effect_4:
cmp #$4
bne effect_5
lda (PATTERN_L),Y ; load byte, set as ornament position
iny
sta note_a+NOTE_ORNAMENT_POSITION,X
bne no_effect ; branch always
;==============================
; Effect #5 -- Vibrato
;==============================
effect_5:
cmp #$5
bne effect_8
lda (PATTERN_L),Y ; load byte, set as onoff delay
iny
sta note_a+NOTE_ONOFF_DELAY,X
sta note_a+NOTE_ONOFF,X
lda (PATTERN_L),Y ; load byte, set as offon delay
iny
sta note_a+NOTE_OFFON_DELAY,X
lda #0
sta note_a+NOTE_TONE_SLIDE_COUNT,X
sta note_a+NOTE_TONE_SLIDING_L,X
sta note_a+NOTE_TONE_SLIDING_H,X
beq no_effect ; branch always
;==============================
; Effect #8 -- Envelope Down
;==============================
effect_8:
cmp #$8
bne effect_9
; delay
lda (PATTERN_L),Y ; load byte, set as speed
iny
sta pt3_envelope_delay_smc+1
sta pt3_envelope_delay_orig_smc+1
; low value
lda (PATTERN_L),Y ; load byte, set as low
iny
sta pt3_envelope_slide_add_l_smc+1
; high value
lda (PATTERN_L),Y ; load byte, set as high
iny
sta pt3_envelope_slide_add_h_smc+1
bne no_effect ; branch always
;==============================
; Effect #9 -- Set Speed
;==============================
effect_9:
cmp #$9
bne no_effect
lda (PATTERN_L),Y ; load byte, set as speed
iny
sta pt3_speed_smc+1
no_effect:
;================================
; add y into the address pointer
clc
tya
adc note_a+NOTE_ADDR_L,X
sta note_a+NOTE_ADDR_L,X
lda #0
adc note_a+NOTE_ADDR_H,X
sta note_a+NOTE_ADDR_H,X
sta PATTERN_H
rts
;=======================================
; Set Envelope
;=======================================
; pulls out common code from $1X and $BX
; commands
; A = new envelope type
set_envelope:
sta pt3_envelope_type_smc+1 ; 4
; give fake old to force update? maybe only needed if printing?
; pt3->envelope_type_old=0x78;
lda #$78 ; 2
sta pt3_envelope_type_old_smc+1 ; 4
; get next byte
iny ; 2
lda (PATTERN_L),Y ; 5+
sta pt3_envelope_period_h_smc+1 ; 4
iny ; 2
lda (PATTERN_L),Y ; 5+
sta pt3_envelope_period_l_smc+1 ; 4
lda #1 ; 2
sta note_a+NOTE_ENVELOPE_ENABLED,X ; envelope_enabled=1 ; 5
lsr ; 2
sta note_a+NOTE_ORNAMENT_POSITION,X ; ornament_position=0 ; 5
sta pt3_envelope_delay_smc+1 ; envelope_delay=0 ; 4
sta pt3_envelope_slide_l_smc+1 ; envelope_slide=0 ; 4
sta pt3_envelope_slide_h_smc+1 ; 4
rts ; 6
;===========
; 64
;========================
; reset note
;========================
; common code from the decode note code
reset_note:
lda #0 ; 2
sta note_a+NOTE_SAMPLE_POSITION,X ; sample_position=0 ; 4
sta note_a+NOTE_AMPLITUDE_SLIDING,X ; amplitude_sliding=0 ; 4
sta note_a+NOTE_NOISE_SLIDING,X ; noise_sliding=0 ; 4
sta note_a+NOTE_ENVELOPE_SLIDING,X ; envelope_sliding=0 ; 4
sta note_a+NOTE_ORNAMENT_POSITION,X ; ornament_position=0 ; 4
sta note_a+NOTE_TONE_SLIDE_COUNT,X ; tone_slide_count=0 ; 4
sta note_a+NOTE_TONE_SLIDING_L,X ; tone_sliding=0 ; 4
sta note_a+NOTE_TONE_SLIDING_H,X ; 4
sta note_a+NOTE_TONE_ACCUMULATOR_L,X ; tone_accumulator=0 ; 4
sta note_a+NOTE_TONE_ACCUMULATOR_H,X ; 4
sta note_a+NOTE_ONOFF,X ; onoff=0; ; 4
rts ; 6
;============
; 52