#205 VGA text mode minor enhancements

[Jindrich Makovicka]

The attached patch adds the following features:

• VGA text mode smooth horizontal panning support
• underline display
• Disabling of the display via BIOS (ah=0x12,bl=0x36)

I wrote it after trying the EGA/VGA compatibility tests in DisplayMate for DOS. It's probably not of much use elsewhere, but the horizontal text scrolling looks nice :)

[Jindrich Makovicka]

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File Added: vga.diff

[Jindrich Makovicka]

VGA panning/underline/on-off support

[Jindrich Makovicka]

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File Added: vga.diff

[c2woody]

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Thanks for the patch, textmode pel panning and underline
capability have been added for machine=vgaonly, should
work the same as your implementation.
Don't have displaymate, maybe you can check that it works
as expected.

[Jindrich Makovicka]

VGA_TEXT_Draw_Line_9 additions

[Jindrich Makovicka]

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I had to modify the Draw_Line_9 function a bit to work properly. The current CVS duplicates/zeroes the pixels based on the screen coordinates, which is IMHO wrong. The patched version always duplicates the pixels at the character boundaries.

There was also an off-by-one error in the split screen handling, causing the last line on the top part to be drawn without panning.

File Added: panning.diff

[Qbix]

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Assigned to c2woody

[Jindrich Makovicka]

VGA_TEXT_Draw_Line_9 additions/fixes

[Jindrich Makovicka]

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Another update, this time with fixed SEQ/ATTR register handling. ATTR.mode_control controls only the 9th bit replication for semigraphic characters. 8bit/9bit display is selected via SEQ.clocking_mode.

File Added: panning2.diff