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mode7_demo: paramaterize scrolling code

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This commit is contained in:
Vince Weaver 2017-12-17 23:40:52 -05:00
parent f0a2779fe8
commit a3c4beea48
2 changed files with 84 additions and 27 deletions
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33
asm_routines/hlin_clearscreen.s
View File

@ -24,6 +24,31 @@ clear_screens:
rts
clear_screens_notext:
;===================================
; Clear top/bottom of page 0
;===================================
lda #$0
sta DRAW_PAGE
jsr clear_top
lda #$0
jsr clear_bottom_a
;===================================
; Clear top/bottom of page 1
;===================================
lda #$4
sta DRAW_PAGE
jsr clear_top
lda #$0
jsr clear_bottom_a
rts
;================================
; hlin_setup
;================================
@ -156,7 +181,7 @@ clear_top_a:
sta COLOR
; VLIN Y, V2 AT A
; HLIN Y, V2 AT A
lda #40
sta V2
@ -177,8 +202,14 @@ clear_top_loop:
rts
;=============================
; clear_bottom
;=============================
clear_bottom:
lda #$a0 ; NORMAL space
clear_bottom_a:
sta COLOR
lda #40

78
mode7_demo/mode7_demo.s
View File

@ -4,8 +4,9 @@
; Clear screen and setup graphics
;================================
jsr clear_screens ; clear top/bottom of page 0/1
jsr set_gr_page0
bit FULLGR
jsr clear_screens_notext ; clear top/bottom of page 0/1
lda #$4
sta DRAW_PAGE
@ -44,7 +45,18 @@ demo_loop:
; lda #255
; jsr WAIT
jsr scroll
lda #>deater_scroll
sta INH
lda #<deater_scroll
sta INL
; lda #10
lda #40
sta CV
jsr gr_scroll
;=============
; Fade out
@ -74,48 +86,62 @@ scroll_row2 EQU $8B00
scroll_row3 EQU $8C00
scroll_row4 EQU $8D00
SCROLL_LENGTH EQU $E6
SCROLL_LENGTH EQU $61
OFFSET EQU $62
;========================
; scroll some text
;========================
; RLE compressed data in INL/INH
; CV is Y position to display at
scroll:
gr_scroll:
lda #0
sta ANGLE
sta OFFSET
;=======================
; decompress scroll text
;=======================
lda #>deater_scroll
sta INH
lda #<deater_scroll
sta INL
jsr decompress_scroll
scroll_loop:
ldx #0
ldy ANGLE
lda DISP_PAGE
beq draw_page2
ldy CV
lsr
lda #4
lda gr_offsets,Y ; get position
sta sm1+1
lda gr_offsets+2,Y ; get position
sta sm2+1
lda gr_offsets+4,Y ; get position
sta sm3+1
lda gr_offsets+6,Y ; get position
sta sm4+1
iny
clc
lda gr_offsets,Y ; get position
adc DRAW_PAGE
sta sm1+2
lda gr_offsets+2,Y ; get position
adc DRAW_PAGE
sta sm2+2
lda #5
lda gr_offsets+4,Y ; get position
adc DRAW_PAGE
sta sm3+2
lda gr_offsets+6,Y ; get position
adc DRAW_PAGE
sta sm4+2
jmp draw_done
draw_page2:
lda #8
sta sm1+2
sta sm2+2
lda #9
sta sm3+2
sta sm4+2
draw_done:
ldy OFFSET
draw_loop:
@ -158,16 +184,16 @@ sm4:
; loop forever
;==================
clc
lda ANGLE
lda OFFSET
adc #40
cmp SCROLL_LENGTH
bne blah
lda #0
sta ANGLE
sta OFFSET
jmp scroll_loop
blah:
inc ANGLE
inc OFFSET
jmp scroll_loop ; 3