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chiptune: shave 8 cycles off of dual 6522 write

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This commit is contained in:
Vince Weaver 2018-02-23 22:13:56 -05:00
parent c13a5333c4
commit c811dbd344
2 changed files with 16 additions and 30 deletions
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44
asm_routines/mockingboard_a.s
View File

@ -76,51 +76,37 @@ reset_ay_both:
; Write sequence
; Inactive -> Latch Address -> Inactive -> Write Data -> Inactive
;=======================
; Write Right AY-3-8910
;=======================
;=========================================
; Write Right/Left to save value AY-3-8910
;=========================================
; register in X
; value in MB_VALUE
write_ay_both:
; address
stx MOCK_6522_ORA1 ; put address on PA ; 3
lda #MOCK_AY_LATCH_ADDR ; latch_address on PB ; 2
sta MOCK_6522_ORB1 ; 3
stx MOCK_6522_ORA1 ; put address on PA1 ; 3
stx MOCK_6522_ORA2 ; put address on PA2 ; 3
lda #MOCK_AY_LATCH_ADDR ; latch_address on PB1 ; 2
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 3
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 3
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 3
; value
lda MB_VALUE ; 3
sta MOCK_6522_ORA1 ; put value on PA ; 3
lda #MOCK_AY_WRITE ; write on PB ; 2
sta MOCK_6522_ORB1 ; 3
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 3
;=======================
; Write Left AY-3-8910
;=======================
;write_ay_left:
; address
stx MOCK_6522_ORA2 ; put address on PA ; 3
lda #MOCK_AY_LATCH_ADDR ; latch_address on PB ; 2
sta MOCK_6522_ORB2 ; 3
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB2 ; 3
; value
lda MB_VALUE ; 3
sta MOCK_6522_ORA2 ; put value on PA ; 3
lda #MOCK_AY_WRITE ; write on PB ; 2
sta MOCK_6522_ORB2 ; 3
sta MOCK_6522_ORA1 ; put value on PA1 ; 3
sta MOCK_6522_ORA2 ; put value on PA2 ; 3
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 3
sta MOCK_6522_ORB2 ; write on PB2 ; 3
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 3
sta MOCK_6522_ORB2 ; 3
rts ; 6
;===========
; 61
; 53
;=======================================
; clear ay -- clear all 14 AY registers
; should silence the card

2
chiptune_player/chiptune_player.s
View File

@ -306,7 +306,7 @@ mb_not_13:
jsr write_ay_both ; assume 3 channel (not six) ; 6
; so write same to both
; left/right
; 61
; 53
clc ; point to next interleaved ; 2
lda INH ; page by adding $300 ; 3