vgabios: Support custom fonts in vga framebuffer text writing.

Obtain the font data from int 0x43 and int 0x1f, and obtain the font
height from the BDA.  This enables application overrides for the font
data.

This patch also unifies the variable naming between the
planar/CGA/linear character writing functions and uses the same names
that the screen scrolling functions use.

This patch also optimizes the inner loop of the CGA font writing to
reduce overall stack usage.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
1 file changed