Raw images contain supplementary information like synchronization fields,
correction codes etc. that needs to be ignored/discarded when
reading/writing user data.
This commit establish a basic architecture for exchanging user data
between a virtual device and a raw image.
The RR0_RX_CHARACTER_AVAILABLE bit is cleared after the character is read in receive_byte, but clear it anyway in read_reg when there's no character available just in case a character that was available somehow becomes unavailable.
Normally, the Port_B_Data or Port_A_Data address is used to directly access RR8 or WR8, but setting the register pointer in Port_B_Cmd or Port_A_Cmd to RR8/WR8 is another option.
Update write_regs[WR8] and read_regs[RR8] for possible debugging purposes.
Update write_regs[WR9] even though most or all of the bits are in master_int_cntrl.
Fix hardware reset for WR9. It's supposed to leave WR9_NO_VECTOR | WR9_VECTOR_INCLUDES_STATUS unchanged.
Fix channel reset for WR9. It's supposed to clear WR9_INTERRUPT_MASKING_WITHOUT_INTACK.
Add absolute coordinates for tablets. Absolute coordinates is relative to window so it can't work for multiple displays? Doesn't work for single display without mouse driver modification.
Add arbitrary number of buttons. Previously, only one mouse button was supported.
Add arbitrary number of bits. Previously, only 7 bits per axis was supported which is good enough for relative movement but not absolute movement.
Allow the dbdma program to initiate reading/writing by adding in and out callbacks.
Support the DBDMA flush command by adding a flush callback. If the transfer completes, then clear the flush flag, otherwise leave it unchanged.
Clear the flush flag after it is copied to the xferStatus of the DBDMA command.
Switching from Watch to Arrow cursor at vertical position zero (top of the screen) would sometimes cut off the top half of the Arrow cursor. The following changes fix this:
Use the new cursor_dirty flag to signal when the cursor should be updated. This reduces the number of cursor updates and doesn't depend on registers being accessed in a specific order.
Set the cursor_dirty flag for any change that should cause the hardware cursor to be updated:
- CUR_CLR0, CUR_CLR1: Cursor color changes. We don't check if the colors actually changed (all cursors are usually black and white). Rather, writes to these registers usually means the cursor bytes have changed or will change.
- CUR_OFFSET: Offset to cursor bytes.
- CUR_VERT_OFF: First vertical line of cursor to draw.
Other changes that don't require the cursor to be updated:
- CUR_HORZ_OFF: Horizontal offset of cursor position. The cursor is unchanged - just need to adjust the drawing position.
- CUR_HORZ_VERT_POSN: The cursor is unchanged - only the drawing position is changed.
The only thing that could change the cursor that we don't check is a change to the cursor bytes.
