graphics.doc

汇编源代码大全

****************************** GRAPHICS *************************************

ASMLIB Graphics (C) Copyright 1991 - 1993 Douglas Herr
All rights reserved

ASMLIB recognizes and automatically supports several graphics modes,
including several which are not recognized by IBM's BIOS.  You should
assume that all ASMLIB graphics subroutines write directly to the video
hardware.  IMPORTANT: ALL ASMLIB GRAPHICS SUBROUTINES ASSUME DS:@DATA.

Locations on Graphics screens are defined by coordinate pairs such as (x,y).
X-coordinates are the horizontal dimensions of the screen, and Y-coordinates
are the vertical coordinates.  X = 0 is the at the left edge of the screen,
and X = 719 is the right edge of a Hercules screen, while Y = 0 is the top
edge of the screen and Y = 347 is the bottom (Hercules).  Thus, the
coordinate specified by (719,0) is the extreme upper right corner of a
Hercules screen.

Graphics subroutines as powerful and flexible as ASMLIB's can be quite
large.  If you have licenced ASMLIB source code, you can use several
pre-defined conditional assembly directives to eliminate code from
ASMLIB object files if you do not want or need to support all graphics
modes:

        NOHERC      eliminates all Hercules and InColor code
        NOINCOLOR   eliminates code for the InColor card
               (InColor works with Hercules monochrome code in 2 colors)
        NO256       eliminates code for the three 256-color modes
        NOCGA       eliminates code for CGA graphics modes
        NOMCGA      elimiates code for MCGA mode 11h
        NOLPATTERN  elimiates code for non-solid lines (in DRAWLINE.ASM)

for example, if you want line drawing programs to use only EGA/VGA-type
16-color modes, assemble DRAWLINE.ASM like this:

         C:\MASM\>masm /dnoherc /dnocga /dnovga256 /dnomcga drawline;

this reduces the size of drawline.obj significantly and speeds its
operation somewhat.

BitBlock subroutines in ASMHUGE.LIB work with huge data blocks (larger
than 64k).  This permits entire EGA, VGA or InColor screens to be saved
in one block if sufficient RAM is available.


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