fastchr.asm
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;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;+ +
;+ This asm file contains 2 pascal procedures for +
;+ linking with TTT version 5.0. The procedures are: +
;+ +
;+ scrolllistup; +
;+ scrolllistdown; +
;+ +
;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
data segment byte public
extrn snowcheck:byte
extrn usebios:byte
extrn vidseg:word
extrn windmin,windmax:word
xpos db ?
ypos db ?
data ends
code segment byte public
assume cs:code,ds:data
public fastchr
;++++++++++++++++++++++++++++++++++++
;+ C A L M E M P O I N T E R +
;++++++++++++++++++++++++++++++++++++
;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;+ +
;+ CALCMEMPOINTER is a local procedure that is called by +
;+ Fastwrite, PlainWrite and Attribute. It places the segment +
;+ and offset of the first attribute, in ES:DI ready for an +
;+ LDS. Vseg and Vofs point to the first attribute of the +
;+ screen, the final location is computed by adding Row*160 +
;+ (80 attribs and 80 chars per row) and then adding 2*Col. +
;+ The passed Row and Column are decremented by one to fit +
;+ with DOS's 0..79, 0..24 coordinate system. +
;+ +
;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
calcmempointer proc near
xor ax,ax ;AX=0
mov cl,al ;CL=0
mov bh,al ;BH=0
shr cx,1 ;CX=Y*128
mov di,cx ;store in DI
shr di,1 ;DI=y*64
shr di,1 ;DI=y*32
add di,cx ;DI=y*160
shl bx,1 ;account for attribute bytes
add di,bx ;DI=(y*160)+(x*2)
mov es,vidseg ;ES:DI points to color attribute
ret
calcmempointer endp
;+++++++++++++++++++++++++++++++++++++++
;+ F A S T C H R +
;+++++++++++++++++++++++++++++++++++++++
wattr equ byte ptr [bp+6] ;write attribute
wchr equ byte ptr [bp+8] ;write character
fastchr proc far
push bp ;Save BP
mov bp,sp ;Set up stack frame
mov ax,40h
mov es,ax
mov bx,es:word ptr [0050h] ;X position [0040:0050]
mov cx,es:word ptr [0051h] ;Y position [0040:0051]
mov xpos,bl
mov ypos,cl
cmp usebios,1 ;check whether to use BIOS
je FCusebios1
FCdirectscr1:
mov ch,cl
mov cl,0
mov bh,cl
call calcmempointer
mov bh,wattr ;attribute
mov bl,wchr ;character
cmp snowcheck,1 ;check whether to check snow
jne FCdoch5
push ax
mov dx,03DAh
FCdoch1:
cli ;interrupts OFF
FCdoch2:
in al,dx ;get 6845 status
test al,8 ;check for vertical retrace
jnz FCdoch4 ;in progress? go..
rcr al,1 ;wait for end of horizontal
jc FCdoch2 ; retrace
FCdoch3:
in al,dx ;get 6845 status again
rcr al,1 ;wait for horizontal
jnc FCdoch3 ; retrace
FCdoch4:
mov ax,bx
stosw ;store video word into ES:DI
sti ;interrupts ON
jmp FCdoch6 ;ALL DONE!
FCdoch5:
mov ax,bx
stosw ;no waiting!!!!!
FCdoch6:
jmp FCmovecursor
FCusebios1:
;assumes that cursor is already positioned to the correct place on the screen
mov ah,9 ;service=write attr & chr at cursor
mov al,wchr ;write character
mov bh,0 ;page 0
mov bl,wattr ;write attribute
mov cx,1 ;write 1x
int 10h
FCmovecursor:
mov ax,windmin
mov bx,windmax
mov dl,xpos ;X pos in DL
mov dh,ypos ;Y pos in DH
inc dl ;increment X
cmp dl,bl ;is X>79 ??
jg FCmc1
jmp FCnoscroll
FCmc1:
mov dl,al ;X:=0
inc dh ;increment Y
cmp dh,bh ;is Y>25 ??
jg FCmc2
jmp FCnoscroll
FCmc2:
;scrolling stuff
cmp usebios,1 ;check whether to use BIOS
jne FCdirectscr2
jmp FCusebios2
FCdirectscr2:
push ds ;save DS ...
mov al,snowcheck ;grab before changing DS
push ax
mov dx,windmax
mov cx,windmin
sub dh,ch ;difference in DH (Y)
mov dl,0
shr dx,1 ;DX=Y*128
shr dx,1 ;DX=Y*64
mov cx,dx ;store in CX
shr cx,1 ;CX=Y*32
shr cx,1 ;CX=Y*16
add cx,dx ;CX=Y*80
push cx
mov cx,0
mov bx,windmin ;BL=X position
mov ch,bh ;CH=Y position
mov bh,0
inc ch ;2nd line of window
call calcmempointer
mov ds,vidseg
mov si,di ;DS:SI
mov dx,ds
mov es,dx ;ES:DI
sub di,0A0h
pop cx
cld ;set direction to FORWARD
pop ax
cmp al,1 ;check whether to check snow
jne FCdscr5
mov dx,03DAh
FCdscr1:
cli ;interrupts OFF
FCdscr2:
in al,dx ;get 6845 status
test al,8 ;check for vertical retrace
jnz FCdscr4 ;in progress? go..
rcr al,1 ;wait for end of horizontal
jc FCdscr2 ; retrace
FCdscr3:
in al,dx ;get 6845 status again
rcr al,1 ;wait for horizontal
jnc FCdscr3 ; retrace
FCdscr4:
movsw ;move it out...
sti ;interrupts ON
loop FCdscr1 ;get next video word
jmp FCdscr6 ;ALL DONE!
FCdscr5:
rep movsw ;no waiting!!!!!
FCdscr6:
pop ds
mov cx,windmin
mov dx,windmax
mov dl,cl
jmp FCnoscroll
FCusebios2:
mov cx,ax ;windmin
mov dx,bx ;windmax
mov ax,0601h ;func=scroll up, 1 line
mov bh,wattr
int 10h
mov dl,cl ;X=windmin's X position (1)
FCnoscroll:
mov ah,2
mov bh,0
int 10h
mov sp,bp ;Restore SP
pop bp ;Restore BP
ret ;Remove parameters and return
fastchr endp
code ends
end