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xmas2018: time analyze the hgr scrolling

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This commit is contained in:
Vince Weaver 2018-12-20 11:23:22 -05:00
parent 5d4005567f
commit 2426cae3c3
1 changed files with 99 additions and 34 deletions
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133
xmas_2018/merry.s
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@ -187,15 +187,32 @@ COUNTL = $04
;===========================================
;===========================================
;===========================================
; Scroll HGR Left
;
; very slowly scroll screen left, 1/3 of screen at a time
; scrolls page pointed to by INL:INH into OUTL:OUTH
; Timing
; scroll_hgr_left: 8
; 140* scroll_hgr_loop: 13 setup
; 64*left_one_loop 30+2*???
; 41 (increments)
; 29 increment counts
; 10 check and loop
; 5 return
; total time = 13 + 140*(13+29+10+64*(41+30+2*(3727)))
; original time = 67,431,293 cycles = roughly 67s
scroll_hgr_left:
lda #$0 ; 2
sta COUNTH ; 3
sta COUNTL ; 3
;===========
; 8
scroll_hgr_loop:
lda #$40 ; 2
sta OUTH ; 3
lda #$60 ; 2
@ -204,21 +221,31 @@ scroll_hgr_smc:
lda #$0 ; 2
sta INL ; 3
sta OUTL ; 3
;============
; 13
; repeats 64 times, once for east hline of 1/3 the screen
left_one_loop:
jsr hgr_scroll_line ; 6+???
lda OUTH
sta TEMP
lda INH
sta OUTH
; scroll first page
jsr hgr_scroll_line ; 6+???
lda TEMP
sta OUTH
; scroll second page
lda OUTH ; 3
sta TEMP ; 3
lda INH ; 3
sta OUTH ; 3
jsr hgr_scroll_line ; 6+???
; restore pointers
lda TEMP ; 3
sta OUTH ; 3
;============
; 30+2*???
clc ; 2
lda INL ; 3
@ -237,8 +264,12 @@ left_one_loop:
sta OUTH ; 3
cmp #$60 ; 2
bne left_one_loop
bne left_one_loop ; 3
;==========
; 41
; -1
lda KEYPRESS ; 4
bmi scroll_done ; 3
@ -251,6 +282,9 @@ left_one_loop:
sta COUNTL ; 3
inc COUNTH ; 5
;===========
; 29
scroll_noinc_counth:
lda COUNTH ; 3
cmp #20 ; 2
@ -258,51 +292,75 @@ scroll_noinc_counth:
;-1
jmp scroll_hgr_loop ; 3
;==========
; 10
scroll_done:
rts ; 6
;===========================================
; hgr_scroll_line
;===========================================
;
; 2 init
; 40*
; hgr_scroll_line_loop: 20
; high bit 22
; get_offpage_byte: 5
; prepare bits: 18
; output new byte: 21
; increment and loop: 7
; 5 return
;
; total = (93*40)+7=3727
hgr_scroll_line:
ldy #0 ; 2
;===========
; 2
hgr_scroll_line_loop:
lda (OUTL),Y ; get pixel block of interest ; 5
sta CURRENT ; 3
iny ; 2
lda (OUTL),Y ; get subsequent pixel block ; 5
;(note, 6 if off end?)
lda (OUTL),Y ; get subsequent pixel block ; 5/6 if off end
sta NEXT ; 3
dey ; restore Y ; 2
;============
; 20
lda COUNTL
cmp #2
beq move_high_bit
cmp #6
beq move_high_bit
bne keep_high_bit
high_bit:
lda COUNTL ; 3
cmp #2 ; 2
beq move_high_bit ; 3
cmp #6 ; -1,2
beq move_high_bit ; 3
bne keep_high_bit ; -1,3
move_high_bit:
lda NEXT
jmp done_high_bit
lda NEXT ; 3
jmp done_high_bit ; 3
keep_high_bit:
lda CURRENT ; 3
done_high_bit:
and #$80 ; 2
sta HIGH ; 3
;===================
; worst: 22
cpy #39
bne not_thirtynine
sty TEMPY
ldy #0
lda (INL),Y
sta NEXT
ldy TEMPY
get_offpage_byte:
cpy #39 ; 2
bne not_thirtynine ; 3
sty TEMPY ; 3
ldy #0 ; 2
lda (INL),Y ; 5
sta NEXT ; 3
ldy TEMPY ; 3
;===================
; usually: 5
not_thirtynine:
; get right byte, bottom 2 bits, shifted left to be in 6+5
lda NEXT ; 3
and #$3 ; 2
asl ; 2
@ -311,19 +369,26 @@ not_thirtynine:
asl ; 2
asl ; 2
sta NEXT ; 3
;==========
; 18
; get current, mask off bottom 2 bits (no longer needed)
; then OR in the saved high (color) bit as well as NEXT bits
lda CURRENT ; 3
lsr ; 2
lsr ; 2
and #$1f ; 2
ora HIGH ; 3
ora NEXT ; 3
sta (OUTL),Y ; 6
;===========
; 21
iny ; 2
cpy #40 ; 2
bne hgr_scroll_line_loop ; 3
; -1
;===========
; 7
; -1
rts ; 6