Hello Manuel!
the idea has become a working source!
With Magoo we have done a small vscreen level demo
you will find it very soon on vscreen web page
vscreen.hypercu.be
In order to unveil the solution for vertical scroll here follows
the CORE part of the code that is devolved to the rendering of
the screen.
Unfortunately this time you cannot just compile & run but you need
all the vscreen initializations and support routines.
Btw everything is ready and will soon appear at vscreen.hypercu.be.
Enjoy
; VDP ports
;
vdpport0 equ 098h ; VRAM read/write
vdpport1 equ 099h ; VDP registers read/write
vdpport2 equ 09ah ; Palette registers write
vdpport3 equ 09bh ; Indirect register write
;----------------------------------
Nline equ 24
;----------------------------------
startProgram:
di
scr4_init
page1
vdpw 19,Nline*8-3
.loop
call testdir
call display
; from here preserve hl and de
vdpw 15,1
wait_FH
vdpw 15,2
wait_hbl
scr5
call plotscreen
scr4
page1
vdpw 15,0
call testesc
jp nz,.loop
ei
jp ending
;;************************************************************
;; Test if esc key is pressed.
;; If pressed, z flag is positioned to 0
;;************************************************************
;testesc:
; in a,(#aa)
; and %11110000
; add a,7
; out (#aa),a
; in a,(#a9)
; and 4
; ret
;*********************************************************
; I/O
;*********************************************************
testdir
ld a,8
out (#aa),a
in a,(#a9)
ld hl,X
.ri bit 7,a
jp nz,.le
inc (hl)
jp .up
.le bit 4,a
jp nz,.up
dec (hl)
.up ld hl,Y
bit 5,a
jp nz,.dw
dec (hl)
.dw bit 6,a
jp nz,.fire
inc (hl)
.fire ;bit 0,a
ret
;*********************************************************
;
;Set VDP port #98 to start writing at address AHL (17-bit)
;
SetVdp_Write: rlc h
rla
rlc h
rla
srl h
srl h
vdp 14 ;set bits 15-17
ld a,l ;set bits 0-7
out (vdpport1),a
ld a,h ;set bits 8-14
or 64 ; + write access
out (vdpport1),a
ret
;*********************************************************
X: db 0
Y: db 0
;Input: D = Dividend, E = Divisor, A = 0
;Output: D = Quotient, A = Remainder
Div8:
xor a
rept 8
sla d
rla
cp e
jr c,$+4
sub e
inc d
endm
ret
;*********************************************************
;
; display the screen at coordinate X,Y in the logical map
;
; logical map : 128x256 stored in VRAM at #8000 (scr5 page 1)
; screen : 32x24 stored in VRAM at #1800 (scr4)
;
display
; e := (Y) mod 24
; a := (Y) / 24
ld a,(Y)
ld d,a
ld e,24
call Div8
ld c,a
ld b,0
; hl := offset[2*bc]
sla bc
ld hl,offset
add hl,bc
ldi bc,(hl)
ld hl,bc
; a: = d*24
ld a,d
add a,d
add a,d
rept 3
add a,a
endm
ld d,a
ld a,(X)
ld e,a
ret
offset
dw l01
dw l11
dw l21
dw l31
dw l41
dw l51
dw l61
dw l71
dw l81
dw l91
dw l101
dw l111
dw l121
dw l131
dw l141
dw l151
dw l161
dw l171
dw l181
dw l191
dw l201
dw l211
dw l221
dw l231
plotscreen:
ld c,vdpport3
rept 8
ld a,(hl)
cp -1
ret z
vdpw 17,32
out (c),e ; Xorg
out (c),0
ldi a,(hl)
add a,d ; multiplo di 24
out (vdpport3),a ; Yorg
ld a,1
out (vdpport3),a ; Yorgpage
outi ; Xdst
out (c),0
ldi a,(hl)
add a,48
out (vdpport3),a ; #1800 Ydst
out (c),0
outi ; DX
out (c),0
outi ; DY
out (c),0
out (c),0
out (c),0
ld a,#D0
out (vdpport3),a
wait_CE
endm
ret
l01
db 0,0,0,64,6
db 6,64,0,64,6
db 12,128,0,64,6
db 18,192,0,64,6
db -1
l11
db 1,192,0,64,5
db 6,0,0,64,6
db 12,64,0,64,6
db 18,128,0,64,6
db 24,192,5,64,1
db -1
l21
db 1,128,0,64,5
db 7,192,0,64,5
db 12,0,0,64,6
db 18,64,0,64,6
db 24,128,5,64,1
db 30,192,5,64,1
db -1
l31
db 1,64,0,64,5
db 7,128,0,64,5
db 13,192,0,64,5
db 18,0,0,64,6
db 24,64,5,64,1
db 30,128,5,64,1
db 36,192,5,64,1
db -1
l41
db 1,0,0,64,5
db 7,64,0,64,5
db 13,128,0,64,5
db 19,192,0,64,5
db 24,0,5,64,1
db 30,64,5,64,1
db 36,128,5,64,1
db 42,192,5,64,1
l51
db 2,192,0,64,4
db 7,0,0,64,5
db 13,64,0,64,5
db 19,128,0,64,5
db 24,192,4,64,2
db 30,0,5,64,1
db 36,64,5,64,1
db 42,128,5,64,1
l61
db 2,128,0,64,4
db 8,192,0,64,4
db 13,0,0,64,5
db 19,64,0,64,5
db 24,128,4,64,2
db 30,192,4,64,2
db 36,0,5,64,1
db 42,64,5,64,1
l71
db 2,64,0,64,4
db 8,128,0,64,4
db 14,192,0,64,4
db 19,0,0,64,5
db 24,64,4,64,2
db 30,128,4,64,2
db 36,192,4,64,2
db 42,0,5,64,1
l81
db 2,0,0,64,4
db 8,64,0,64,4
db 14,128,0,64,4
db 20,192,0,64,4
db 24,0,4,64,2
db 30,64,4,64,2
db 36,128,4,64,2
db 42,192,4,64,2
l91
db 3,192,0,64,3
db 8,0,0,64,4
db 14,64,0,64,4
db 20,128,0,64,4
db 24,192,3,64,3
db 30,0,4,64,2
db 36,64,4,64,2
db 42,128,4,64,2
l101
db 3,128,0,64,3
db 9,192,0,64,3
db 14,0,0,64,4
db 20,64,0,64,4
db 24,128,3,64,3
db 30,192,3,64,3
db 36,0,4,64,2
db 42,64,4,64,2
l111
db 3,64,0,64,3
db 9,128,0,64,3
db 15,192,0,64,3
db 20,0,0,64,4
db 24,64,3,64,3
db 30,128,3,64,3
db 36,192,3,64,3
db 42,0,4,64,2
l121
db 3,0,0,64,3
db 9,64,0,64,3
db 15,128,0,64,3
db 21,192,0,64,3
db 24,0,3,64,3
db 30,64,3,64,3
db 36,128,3,64,3
db 42,192,3,64,3
l131
db 4,192,0,64,2
db 9,0,0,64,3
db 15,64,0,64,3
db 21,128,0,64,3
db 24,192,2,64,4
db 30,0,3,64,3
db 36,64,3,64,3
db 42,128,3,64,3
l141
db 4,128,0,64,2
db 10,192,0,64,2
db 15,0,0,64,3
db 21,64,0,64,3
db 24,128,2,64,4
db 30,192,2,64,4
db 36,0,3,64,3
db 42,64,3,64,3
l151
db 4,64,0,64,2
db 10,128,0,64,2
db 16,192,0,64,2
db 21,0,0,64,3
db 24,64,2,64,4
db 30,128,2,64,4
db 36,192,2,64,4
db 42,0,3,64,3
l161
db 4,0,0,64,2
db 10,64,0,64,2
db 16,128,0,64,2
db 22,192,0,64,2
db 24,0,2,64,4
db 30,64,2,64,4
db 36,128,2,64,4
db 42,192,2,64,4
l171
db 5,192,0,64,1
db 10,0,0,64,2
db 16,64,0,64,2
db 22,128,0,64,2
db 24,192,1,64,5
db 30,0,2,64,4
db 36,64,2,64,4
db 42,128,2,64,4
l181
db 5,128,0,64,1
db 11,192,0,64,1
db 16,0,0,64,2
db 22,64,0,64,2
db 24,128,1,64,5
db 30,192,1,64,5
db 36,0,2,64,4
db 42,64,2,64,4
l191
db 5,64,0,64,1
db 11,128,0,64,1
db 17,192,0,64,1
db 22,0,0,64,2
db 24,64,1,64,5
db 30,128,1,64,5
db 36,192,1,64,5
db 42,0,2,64,4
l201
db 5,0,0,64,1
db 11,64,0,64,1
db 17,128,0,64,1
db 23,192,0,64,1
db 24,0,1,64,5
db 30,64,1,64,5
db 36,128,1,64,5
db 42,192,1,64,5
l211
db 11,0,0,64,1
db 17,64,0,64,1
db 23,128,0,64,1
db 24,192,0,64,6
db 30,0,1,64,5
db 36,64,1,64,5
db 42,128,1,64,5
db -1
l221
db 17,0,0,64,1
db 23,64,0,64,1
db 24,128,0,64,6
db 30,192,0,64,6
db 36,0,1,64,5
db 42,64,1,64,5
db -1
l231
db 23,0,0,64,1
db 24,64,0,64,6
db 30,128,0,64,6
db 36,192,0,64,6
db 42,0,1,64,5
db -1
endProgram
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