dos33fsprogs/vaporlock/rasterbars/pt3_lib_set_pattern.s
Vince Weaver e0febd1a90 demos: more work
keep making git mistakes urgh
2021-01-05 22:52:10 -05:00

118 lines
2.5 KiB
ArmAsm

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