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LIB_A.ASM

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+;====================================================
+;
+; Library ASM code
+;
+;====================================================
+	IDEAL
+	P386N
+	MODEL	medium,C
+
+extrn	xormask:WORD,yshift:WORD,CGAfont:WORD,VGAfont:WORD
+
+	DATASEG
+
+SCindex	=	3c4h
+SCmapmask =	2
+GCindex =      	3CEh
+GCreadmap =	4
+GCmode 	=	5
+
+a	=	0
+LABEL	CGAlookup WORD
+PUBLIC	CGAlookup
+	REPT	100
+	dw	a,a XOR 2000h
+a	=	a+80
+	ENDM
+
+a	=	0
+LABEL	EGA1lookup WORD
+PUBLIC	EGA1lookup
+	REPT	200
+	dw	a
+a	=	a+40
+	ENDM
+
+a	=	0
+LABEL	EGA2lookup WORD
+PUBLIC	EGA2lookup
+	REPT	480
+	dw	a
+a	=	a+80
+	ENDM
+
+a	=	0
+LABEL	VGAlookup WORD
+PUBLIC	VGAlookup
+	REPT	200
+	dw	a
+a	=	a+320
+	ENDM
+
+
+	CODESEG
+
+;====================================================
+;
+; Draw CGA chars
+;
+;====================================================
+PROC CGAcharout
+PUBLIC CGAcharout
+ARG	x:WORD,y:WORD,chr:BYTE
+USES si,di,ds
+	mov	bx,[y]
+	shl	bx,1
+	shl	bx,1
+	shl	bx,1
+	shl	bx,1
+	mov	di,[CGAlookup+bx]
+	mov	ax,[x]
+	shl	ax,1
+	add	di,ax
+
+	mov	al,[chr]
+	xor	ah,ah
+	shl	ax,1
+	shl	ax,1
+	shl	ax,1
+	shl	ax,1
+	mov	si,ax
+
+	mov	ax,0b800h
+	mov	es,ax
+	mov	ds,[CGAfont]
+	cld
+	cmp	[ss:xormask],0
+	ja	@@1
+
+	REPT	4
+	movsw
+	add	di,2000h-2
+	movsw
+	sub	di,2000h-78
+	ENDM
+	jmp	@@exit
+@@1:
+	REPT	4
+	lodsw
+	xor	ax,0ffffh
+	stosw
+	add	di,2000h-2
+	lodsw
+	xor	ax,0ffffh
+	stosw
+	sub	di,2000h-78
+	ENDM
+@@exit:
+	ret
+ENDP
+
+;====================================================
+;
+; Draw EGA chars
+;
+;====================================================
+PROC EGAcharout
+PUBLIC EGAcharout
+ARG	x:WORD,y:WORD,chr:BYTE,video:WORD
+USES si,di,ds,bp
+
+	mov	dx,GCindex
+	mov	ax,GCmode
+	out	dx,ax
+
+	mov	bx,[y]
+	shl	bx,1
+	shl	bx,1
+	shl	bx,1
+	add	bx,[yshift]
+	shl	bx,1
+
+	cmp	[video],1
+	jne	@@0
+	mov	cx,39
+	mov	di,[EGA1lookup+bx]
+	jmp	@@1
+@@0:
+	mov	cx,79
+	mov	di,[EGA2lookup+bx]
+@@1:
+	add	di,[x]
+
+	mov	ax,0a000h
+	mov	es,ax
+	mov	ds,ax
+
+	mov	si,0f000h
+	mov	al,[chr]
+	xor	ah,ah
+	shl	ax,1
+	shl	ax,1
+	shl	ax,1
+	add	si,ax
+
+	cld
+	cmp	[ss:xormask],0
+	ja	@@2
+
+	mov	dx,GCindex
+	mov	ax,GCmode OR 100h
+	out	dx,ax
+	mov	dx,SCindex
+	mov	ax,SCmapmask OR 0f00h
+	out	dx,ax
+
+	REPT	8
+	movsb
+	add	di,cx
+	ENDM
+	jmp	@@exit
+
+@@2:
+ga	=	100h
+gb	=	0
+	mov	bp,si
+	mov	bx,di
+	REPT	4
+	mov	dx,SCindex
+	mov	ax,SCmapmask OR ga
+	out	dx,ax
+	mov	dx,GCindex
+	mov	ax,GCreadmap OR gb
+	out	dx,ax
+	REPT	8
+	lodsb
+	xor	al,0ffh
+	stosb
+	add	di,cx
+	ENDM
+	mov	di,bx
+	mov	si,bp
+ga	=	ga*2
+gb	=	gb+100h
+	ENDM
+@@exit:
+	mov	dx,GCindex
+	mov	ax,GCmode
+	out	dx,ax
+	ret
+ENDP
+
+;====================================================
+;
+; Draw VGA chars
+;
+;====================================================
+PROC VGAcharout
+PUBLIC VGAcharout
+ARG	x:WORD,y:WORD,chr:BYTE
+USES si,di,ds
+
+	mov	bx,[y]
+	shl	bx,1
+	shl	bx,1
+	shl	bx,1
+	add	bx,[yshift]
+	shl	bx,1
+	mov	di,[VGAlookup+bx]
+
+	mov	ax,[x]
+	shl	ax,1
+	shl	ax,1
+	shl	ax,1
+	add	di,ax
+
+	mov     ah,[chr]
+	xor	al,al
+	shr	ax,1
+	shr	ax,1	;[chr]*64!
+	mov	si,ax
+
+	mov	ax,0a000h
+	mov	es,ax
+	mov	ds,[VGAfont]
+
+	cmp	[ss:xormask],0
+	ja	@@1
+
+	REPT	8
+	REPT	4
+	movsw
+	ENDM
+	add	di,320-8
+	ENDM
+	jmp	@@exit
+@@1:
+	REPT	8
+	REPT	4
+	lodsw
+	xor	ax,0ffffh
+	stosw
+	ENDM
+	add	di,320-8
+	ENDM
+@@exit:
+	ret
+ENDP
+
+END