79 lines
3.2 KiB
Plaintext
79 lines
3.2 KiB
Plaintext
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______ ____ ______ _____ ______
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| ____| | _ \| ____| / / _ \| ____|
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| |__ _ __ ___ ___| |_) | |__ / / |_| | |__
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| __| '__/ _ \/ _ \ _ <| __| / /| _ | __|
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| | | | | __/ __/ |_) | |____ / / | | | | |
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|_| |_| \___|\___|____/|______/_/ |_| |_|_|
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ATI mach64 driver implementation notes.
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This driver is currently a limited implementation of VBE/AF for mach64.
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It is not very well tested and may not work for you (if it doesn't,
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give me your system description and a description of the problems).
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It has a built-in table of known VESA modes, as well as all non-VESA
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modes that the mach64 BIOS supports, but currently the non-VESA mode
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setting doesn't work properly, so only VESA modes are enabled. However,
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it is able to take advantage of extra VESA modes provided by tools like
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Scitech Display Doctor.
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It supports 8, 15, 16, 24, and 32 bits per pixel, if available. It
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currently provides acceleration for these primitives:
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DrawScan()
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DrawPattScan()
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DrawRect()
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DrawPattRect()
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BitBlt()
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SrcTransBlt() (not in 24bpp)
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DrawLine() (not in 24bpp)
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These accelerated functions are planned and may be provided in the
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future:
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DrawTrap() (actually the mach64 seems to be able to draw entire
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polygons, too bad there isn't a DrawPoly() in VBE/AF;
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DrawTri() and DrawQuad() may be possible, but since
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they are not widely used, who cares about them)
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PutMonoImage() (using HOST transfer, perhaps)
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BitBltSys() (using HOST transfer)
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SrcTransBltSys() (same here)
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SetCursor()
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SetCursorPos()
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SetCursorColor()
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ShowCursor()
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This driver is not portable to anything but DOS+DPMI, since it uses
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DPMI to communicate with the mach64 BIOS.
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Both linear and banked modes are supported, but SetBank32 is in the
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current (sloppy) implementation not fully relocatable, but this should
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rarely be a problem since linear modes are much more fun anyway.
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If you want to have 32bpp and 1600x1200 modes without having to
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install Scitech Display Doctor, define REFUSE_VESA and try to find out
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why the mach64 mode settings doesn't work properly, then uncomment the
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appropriate extra modes, and report to me.
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Virtual heights above screen height (for hardware scrolling) may not
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work properly above 8bpp, I'm not sure why yet, but it looks like it
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could be a bug in Allegro.
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DrawLine does not seem to be rounded exactly like Allegro's, which
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becomes evident when clipping.
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I'm not sure how to do patterns. It is possible to load an 8x8 mono
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pattern into the mach64 registers and use it, but I'm not sure how,
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but I made a guess and implemented that, and it seems to work, but
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I'm not totally sure. As for color patterns, I have just disabled
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them since I haven't figured out how to do those yet. It would be
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possible to use Shawn's technique; to bitblt them from offscreen VRAM,
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but use TILE_X enabled for automatic tiling, but it doesn't seem
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worthwhile at present, if there is a better way.
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Ove Kaaven <ovek@arcticnet.no>
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