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rbs: working on cycle-invariance

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This commit is contained in:
Vince Weaver 2019-06-18 17:11:41 -04:00
parent 7017d0b2a8
commit 00479ac953
1 changed files with 27 additions and 8 deletions
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35
interlace_demo/mockingboard_a.s
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@ -239,11 +239,21 @@ mb4_not_in_this_slot:
beq done_mb4_detect
;====================================
; mb_write_frame
;====================================
; cycle counted
; 2 + 13*(28+28+7) + 5
mb_write_frame:
ldx #0 ; set up reg count ; 2
@ -256,17 +266,25 @@ mb_write_frame:
;==================================
mb_write_loop:
;=============================
; not r13 -- 4+5+[ ]+28+28+7
; r13, not ff -- 4+5+ 3 +28+28+7
; r13 is ff -- 4+5+ 4
lda AY_REGISTERS,X ; load register value ; 4
; special case R13. If it is 0xff, then don't update
; otherwise might spuriously reset the envelope settings
cpx #13 ; 2
bne mb_not_13 ; 3/2nt
bne mb_not_13 ; 3
; -1
cmp #$ff ; 2
beq mb_skip_13 ; 3/2nt
;============
; typ 5
beq mb_skip_13 ; 3
; -1
mb_not_13:
@ -279,7 +297,8 @@ mb_not_13:
ldy #MOCK_AY_INACTIVE ; go inactive ; 2
sty MOCK_6522_ORB1 ; 4
sty MOCK_6522_ORB2 ; 4
;==========
; 28
; value
sta MOCK_6522_ORA1 ; put value on PA1 ; 4
sta MOCK_6522_ORA2 ; put value on PA2 ; 4
@ -289,15 +308,15 @@ mb_not_13:
sty MOCK_6522_ORB1 ; 4
sty MOCK_6522_ORB2 ; 4
;===========
; 56
; 28
mb_no_write:
inx ; point to next register ; 2
cpx #14 ; if 14 we're done ; 2
bmi mb_write_loop ; otherwise, loop ; 3/2nt
bmi mb_write_loop ; otherwise, loop ; 3
;============
; 7
mb_skip_13:
; -1
rts ; 6