qemu /
qemu /
3f83435042af241ea8773d04ef3726ce4146bfca vga: use latches in odd/even mode too
Jazz Jackrabbit uses odd/even mode with 256-color graphics. This is
probably so that it can do very fast blitting with a decent resolution
(two pixels, compared to four pixels for "regular" mode X).
Accesses still use all planes (reads go to the latches and the game uses
read mode 1 so that the CPU always gets 0xFF; writes use the plane mask
register because the game sets bit 2 of the sequencer's memory mode
register). For this to work, QEMU needs to use the code for latched
memory accesses in odd/even mode. The only difference between odd/even
mode and "regular" planar mode is how the plane is computed in read mode
0, and how the planes are masked if the aforementioned bit 2 is reset.
It is almost enough to fix the game. You also need to honor byte/word
mode selection, which is done in the next patch.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 file changed
