KEYB_INJ.PRG - A key press injection utility for TOS 1.x
(C) 2019 Christian Zietz <czietz@gmx.net>

Sometimes an application or driver needs to input key press and release 
events as if they were coming from the Atari keyboard itself. TOS 
versions 2 and above as well as EmuTOS provide an API for this task;
however, Atari TOS 1.x does not.

KEYB_INJ.PRG is a utility to provide such applications the address within 
TOS 1.x which handles keyboard events.


- GUIDE FOR USERS -

Place KEYB_INJ.PRG in your AUTO folder. Make sure to sort the folder in 
such a way that KEYB_INJ.PRG is run before any drivers that need it.
Note: If no cookie jar exists, KEYB_INJ.PRG creates its own, which can 
also be used by other programs. Therefore, if your AUTO folder contains a 
program solely to create a cookie jar, you can remove it when using 
KEYB_INJ.PRG.


- GUIDE FOR DEVELOPERS -

KEYB_INJ.PRG sets the 'KINJ' cookie to the address of a routine within 
TOS that can be called similarly as the 'kbdvec' vector available via the 
Kbdvbase() XBIOS call since TOS 2, with the additional requirement that the 
A5 register is zeroed.

In pseudo code:

At the start of a program:
    if TOS version >= 2 or EmuTOS detected:
        ; "negative 1" entry from array returned by Kbdvbase()
        vector = Kbdvbase()[-1]
    else if 'KINJ' cookie detected:
        vector = value of 'KINJ' cookie
    else:
        Fail

To inject a key press or release event:
    Save all registers
    Register A0 = Iorec(1)
    Register D0 = Scancode (or scancode+0x80 for release)
    Register A5 = 0
    Call vector with JSR
    Restore all registers

- LICENSE -

Copyright (c) 2019 Christian Zietz <czietz@gmx.net>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.