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Hardware text-scroll (using no blitter) with Atari computer
DRAGFONT.NEO
**********************************************************************
* Hi... this source is for Turbo-Ass (!!!)....
* (Men det går nästan lika bra med Deve-Devpakken...)
* The source is old, but it shows what ya' can do with hardware-scrolling....
* The source is -NOT- completed or optimized in any way... it's up to YOU!!
* (Det är ej några tecken-avstånd...osv...osv...)
* Du får dissekera koden hur fasen du vill... bye!
**********************************************************************
* Hardware text-scroll (using no blitter) by Techwave of I.C.E.! *
* (4 planes) 32*32 *
**********************************************************************
clr.l -(sp)
move.w #$20,-(sp)
trap #1
addq.l #6,sp
move.w #0,-(sp)
move.l #-1,-(sp)
move.l #-1,-(sp)
move.w #5,-(sp)
trap #14
lea 12(sp),sp
lea fontpic+4(pc),a0
lea $ffff8240.w,a1
rept 8
move.l (a0)+,(a1)+
endr
i_init: move.l $70.w,oldvbl
move.l #vbl,$70.w
move.w #7,-(sp)
trap #1
addq.l #2,sp
rts
**********************************************************************
**********************************************************************
vbl:
rept 5000 ; wait, so U can see the time!
nop
endr
move.w #$0300,$ffff8240.w
movem.l d0-a6,-(sp)
bsr.s hard_txtscrl
movem.l (sp)+,d0-a6
move.w #$00,$ffff8240.w
rte
**********************************************************************
**********************************************************************
hard_txtscrl:
move.w scroll(pc),d1
add.w #16+16,d1
move.w d1,d2
and.b #$0f,d1
move.b d1,$ffff8265.w
bne.s fix_line
move.b #80+8+4,$ffff820f.w ; x-words
bra.s scrn_poi
fix_line: move.b #80-4+8+4,$ffff820f.w
scrn_poi:
lsr.w #4,d2
lsl.w #3,d2
move.l #screen,d0
add.l d2,d0
move.b d0,$ffff8209.w
lsr.w #8,d0
move.b d0,$ffff8207.w
swap d0
move.b d0,$ffff8205.w
cmpi.b #4,word_corr
bne.s no_gfx_move
move.b #0,word_corr
bsr.s b_charout
no_gfx_move: addq.b #1,word_corr
cmpi.w #320+32-4,scroll
blo.s inc_poi
move.w #0,scroll
rts
inc_poi: addi.w #4,scroll
rts
**********************************************************************
scroll: dc.w 0
word_corr: dc.b 4
even
**********************************************************************
b_charout: lea fontpic+128(pc),a0
move.w offset(pc),d0
adda.w d0,a0
movea.l a0,a2
lea screen+8,a1
move.w scroll(pc),d0
and.b #$f0,d0
lsr.w #1,d0
adda.w d0,a1
rept 31
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
lea 160-8(a0),a0
lea 336+8-8(a1),a1
endr
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
movea.l a2,a0
lea screen+160+8+8+8,a1
adda.w d0,a1
rept 31
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
lea 160-8(a0),a0
lea 336+8-8(a1),a1
endr
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
move.w (a0)+,(a1)+
tst.b second_flg ; for x 32
bne.s ready
addq.w #8,offset
st second_flg
rts
ready: sf second_flg
move.w #0,offset
read: moveq #0,d0
lea txt(pc),a0
adda.w txt_pointer(pc),a0
move.b (a0),d0
bne.s ascii
move.w #0,txt_pointer
bra.s read
ascii: sub.b #32,d0
add.w d0,d0
lea char_offs(pc),a0
move.w 0(a0,d0.w),offset
addq.w #1,txt_pointer
rts
**********************************************************************
second_flg: dc.b 0
txt_pointer: dc.w 0
offset: dc.w 0
**********************************************************************
* --------------------------------------------------------------- restore
back: move.l oldvbl,$70.w
move.b #0,$ffff8264.w
move.w #1,-(sp)
move.l #-1,-(sp)
move.l #-1,-(sp)
move.w #5,-(sp)
trap #14
lea 12(sp),sp
rts
**********************************************************************
* --------------------------------------------------------------- data
* starts with "space", 32
char_offs: dc.w $00,$10,$20
dc.w $30,$40,$50
dc.w $60,$70,$80
dc.w $90
dc.w $1400,$1410,$1420
dc.w $1430,$1440,$1450
dc.w $1460,$1470,$1480
dc.w $1490
dc.w $2800,$2810,$2820
dc.w $2830,$2840,$2850
dc.w $2860,$2870,$2880
dc.w $2890
dc.w $3c00,$3c10,$3c20
dc.w $3c30,$3c40,$3c50
dc.w $3c60,$3c70,$3c80
dc.w $3c90
dc.w $5000,$5010,$5020
dc.w $5030,$5040,$5050
dc.w $5060,$5070,$5080
dc.w $5090
dc.w $6400,$6410,$6420
dc.w $6430,$6440,$6450
dc.w $6460,$6470,$6480
dc.w $6490
* --------------------------------------------------------------------
txt:
dc.b "INNER CIRCUIT EXPLORERS... - WE BURN YOUR CIRCUITS TO ASHES - "
dc.b "0123456789 ABCDEFGHIJKLMNOPQRSTUVWXYZ !#$%&/()=?' "
dc.b 0
even
* --------------------------------------------------------------------
oldvbl: dc.l 0
fontpic: ibytes 'DRAGFONT.NEO'
screen: ds.b 32000
end 
