Genesis-Plus-GX/source/input_hw/terebi_oekaki.c

78 lines
2.7 KiB
C

/***************************************************************************************
* Genesis Plus
* Terebi Oekaki graphic board support
*
* Copyright (C) 2011 Eke-Eke (Genesis Plus GX)
*
* Redistribution and use of this code or any derivative works are permitted
* provided that the following conditions are met:
*
* - Redistributions may not be sold, nor may they be used in a commercial
* product or activity.
*
* - Redistributions that are modified from the original source must include the
* complete source code, including the source code for all components used by a
* binary built from the modified sources. However, as a special exception, the
* source code distributed need not include anything that is normally distributed
* (in either source or binary form) with the major components (compiler, kernel,
* and so on) of the operating system on which the executable runs, unless that
* component itself accompanies the executable.
*
* - Redistributions must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************************/
#include "shared.h"
static struct
{
uint8 axis;
uint8 busy;
} tablet;
void terebi_oekaki_reset(void)
{
input.analog[0][0] = 128;
input.analog[0][1] = 128;
tablet.axis = 1;
tablet.busy = 1;
}
unsigned short terebi_oekaki_read(void)
{
uint16 data = (tablet.busy << 15) | input.analog[0][tablet.axis];
if (!(input.pad[0] & INPUT_B))
{
data |= 0x100;
}
/* clear BUSY flag */
tablet.busy = 0;
return data;
}
void terebi_oekaki_write(unsigned char data)
{
/* X (1) or Y (0) axis */
tablet.axis = (data & 1) ^ 1;
/* set BUSY flag */
tablet.busy = 1;
}