The resolution of zaurus akita is 480x640 (or 240x320) instead of 640x480 (or 320x240). While SNES9x uses resolution 640x480 or 320x240, so rotation should be implemented in some layer of the graphic stack. The possible graphic stacks are:
- SNES9x + X Window + frame buffer
- SNES9x + SDL + X Window + frame buffer
- SNES9x + SDL + frame buffer
Rotation has been implemented in X window so for 1 and 2, there is no need to implement rotation in SDL or SNES9x. But the performance of 1 and 2 is worse than 3. So I implement the rotation in SNES9x. The patch can be downloaded here.