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chiptune_player: had timing of absolute store wrong :(

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it's 4 cycles, not 3
This commit is contained in:
Vince Weaver 2018-03-12 13:49:15 -04:00
parent 47b441afb9
commit d85eda74bf
2 changed files with 19 additions and 20 deletions
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12
chiptune_player/README.chiptune
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@ -467,17 +467,17 @@ Interrupt Timing / AY write latency:
====================================
Originally roughly 1500 cycles from start of interrupt
to all AY registers being written.
1500
1600
Moved clock to after, near the visualization stuff, more like
1378 = 13+ (105*13)
1534 = 13+ (117*13)
Load frame data for next time at end of IRQ, instead of begin
1029 = 13+2+(78*13)
1185 = 13+2+(90*13)
Inlined the mockingboard write routine
873 = 13+2+(66*13)
1029 = 13+2+(78*13)
Only write registers that change. Added 6 cycles per loop
951 worst case = 13+2+(10+5+50+7)*13
304 if only one reg changed = 13+2+(18*13)+55
1107 worst case = 13+2+(10+5+62+7)*13
316 if only one reg changed = 13+2+(18*13)+67

27
chiptune_player/interrupt_handler.s
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@ -69,29 +69,28 @@ mb_not_13:
; inlined "write_ay_both" to save 12 cycles
; address
stx MOCK_6522_ORA1 ; put address on PA1 ; 3
stx MOCK_6522_ORA2 ; put address on PA2 ; 3
stx MOCK_6522_ORA1 ; put address on PA1 ; 4
stx MOCK_6522_ORA2 ; put address on PA2 ; 4
lda #MOCK_AY_LATCH_ADDR ; latch_address for PB1 ; 2
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 3
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 3
sta MOCK_6522_ORB1 ; latch_address on PB1 ; 4
sta MOCK_6522_ORB2 ; latch_address on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 3
sta MOCK_6522_ORB2 ; 3
sta MOCK_6522_ORB1 ; 4
sta MOCK_6522_ORB2 ; 4
; value
lda MB_VALUE ; 3
sta MOCK_6522_ORA1 ; put value on PA1 ; 3
sta MOCK_6522_ORA2 ; put value on PA2 ; 3
sta MOCK_6522_ORA1 ; put value on PA1 ; 4
sta MOCK_6522_ORA2 ; put value on PA2 ; 4
lda #MOCK_AY_WRITE ; ; 2
sta MOCK_6522_ORB1 ; write on PB1 ; 3
sta MOCK_6522_ORB2 ; write on PB2 ; 3
sta MOCK_6522_ORB1 ; write on PB1 ; 4
sta MOCK_6522_ORB2 ; write on PB2 ; 4
lda #MOCK_AY_INACTIVE ; go inactive ; 2
sta MOCK_6522_ORB1 ; 3
sta MOCK_6522_ORB2 ; 3
sta MOCK_6522_ORB1 ; 4
sta MOCK_6522_ORB2 ; 4
; 50
;===========
; 50
; 62
mb_no_write:
inx ; point to next register ; 2
cpx #14 ; if 14 we're done ; 2