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