nanogui: Thread: Hercules on ELKS / Microwindows

Hi everybody and Thomas!


Eh... Sorry for crossposting,
but I am a little confused regarding which people
would like to hear this...


Since I have been too lazy/busy to do some hercules coding myself
and others have already given it a try, I post here what I know.

This is taken from a Microsoft Press book from 1987.
It is a book full of asm examples, original title:
"Programmers Guide to PC & PS/2 VIDEO SYSTEMS"
I have the swedish version.
The copyright says (from swedish):
The contents of this book must not be in part or as a whole
copied (xerox etc) or stored on machine-readable media without
the copyrightholders (? dont know the legal term in english)
written permission.

But AFAIK in Sweden it is legal to copy a few pages of
a book for educational purposes...
(I am doing this in Sweden.)
So if this educates someone, I guess it is just fine. :-)

Does any of you know how this legal stuff works?
Do companies expect to sell books containing source code and
then no one typing it into their computers?
(Machine readable media...)
Or is it a silent agreement?

Happy hacking.


ByteOffsetShift EQU 3


PixelAddrHGC:
		


HorizLineHGC:	mov ax,ARGy1
		mov bx,ARGx1
		call PixelAddrHGC
; AH:= bitmask
; ES:BX -> videobuffer
; CL := number of bits leftshift
; ES:DI -> buffer

		mov di, bx
		mov dh,ah
		not dh
		mov d1,0FFh
		shl dh,cl
		not dh
		mov cx,ARG2x
		and cl,7
		xor cl,7
		shl dl,c1

		mov cx,ARGx2
		and cl,7
		xor cl,7
		shl dl,cl

		mov ax,ARGx2
		mov bx,ARGx1
		mov cl,ByteOffsetShift
		shr ax,cl
		shr bx,cl
		mov cx,ax
		sub cx,bx

		mov bx,offset DGROUP:PropagatedPixel
		mov al,ARGn
		xlat
		or dh,dh
		js L43

		cr cx,cx
		jnz L42

		and dl,dh
		jmp short L44

L42:		mov ah,al

		and ah,dh
		not dh
		and es:[di],dh
		or es:[di],ah
		inc di
		dec cx

L43:		rep stosb       ; This instruction does not work on 8088?


L44:		and al,dl
		not dl
		and es:[di],dl
		or es:[di],al

		jmp Lexit

		... .... ... ....; vertical line draw etc.


Lexit:
		pop di
		pop si
		mov sp,bp
		pop bp
		ret

_PropagatedPixel DB    00000000b
                 DB    11111111b




------------------------------------------------------------------

PS

One can pageflip (hello doublebuffered microwin here I come!) between
the 2 graphics frames on HGC.

To write on page 0, use video segment B000H.
To write on page 1, use video segment B800H.


I have forgotten how to flip between the 2 frames, but I will post later
when I have found it out.


Oh, and here is

PixelAddrHGC	PROC near
		mov cl,bl
		shr ax,1
		rcr bx,1
		shr bx,1
		mov ah,BytesPerLine    (that is, 90 /comment)
		mul ah
		add bx,ax
		add bx,OriginOffset
		mov ax,VideoBufferSeg (you know, one of the buffers /comment)
		mov es,ax
		and cl,7
		xor cl,7
		mov ah,1

		ret


--------------------------------------
PS 2

These routines are so _neat_! Small and fast...
I am impressed by the person(s) who thougt them out.

I happen to have source in C, C++ and asm available for free use,
written by myself.  There is also code for 640x480 B&W VGA there too.

The tar file can be had at:

	ftp://ftp.apsoft.com/pub/user/perry/source/herc.tar.gz

If you look at the VGA code, it demostrates the use of a lookup table
for Y coordinate offsets.  A lookup table for herc would be a big
speed win on slow CPUs, just calculate the Y beginning offset at
driver initialization.

> 
> Since I have been too lazy/busy to do some hercules coding myself
> and others have already given it a try, I post here what I know.
> 

--Perry

-- 
Perry Harrington       Linux rules all OSes.    APSoft      ()
email: ####@####.#### 			Think Blue. /\

On Wed, 15 Sep 1999, Perry Harrington wrote:

> I happen to have source in C, C++ and asm available for free use,
> written by myself.  There is also code for 640x480 B&W VGA there too.

Thanks a lot!
This simplifies both coding and legalities.

> The tar file can be had at:
> 
> 	ftp://ftp.apsoft.com/pub/user/perry/source/herc.tar.gz
> 
> If you look at the VGA code, it demostrates the use of a lookup table
> for Y coordinate offsets.  A lookup table for herc would be a big
> speed win on slow CPUs, just calculate the Y beginning offset at
> driver initialization.

Hmm... interesting.
I never thought of that.
Probably the hercules can be really useful.


Regards,
Jakob