142 lines
3.3 KiB
Text
142 lines
3.3 KiB
Text
/*
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* This file is part of libsidplayfp, a SID player engine.
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*
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* Copyright 2011-2015 Leandro Nini <drfiemost@users.sourceforge.net>
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* Copyright 2009-2014 VICE Project
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* Copyright 2007-2010 Antti Lankila
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* Copyright 2001 Simon White
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef LIGHTPEN_H
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#define LIGHTPEN_H
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namespace libsidplayfp
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{
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/**
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* Lightpen emulation.
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* Does not reflect model differences.
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*/
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class Lightpen
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{
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private:
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/// Last VIC raster line
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unsigned int lastLine;
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/// VIC cycles per line
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unsigned int cyclesPerLine;
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/// X coordinate
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unsigned int lpx;
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/// Y coordinate
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unsigned int lpy;
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/// Has light pen IRQ been triggered in this frame already?
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bool isTriggered;
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public:
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/**
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* Set VIC screen size.
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*
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* @param height number of raster lines
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* @param width number of cycles per line
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*/
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void setScreenSize(unsigned int height, unsigned int width)
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{
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lastLine = height - 1;
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cyclesPerLine = width;
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}
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/**
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* Reset the lightpen.
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*/
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void reset()
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{
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lpx = 0;
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lpy = 0;
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isTriggered = false;
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}
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/**
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* Return the low byte of x coordinate.
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*/
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uint8_t getX() const { return lpx; }
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/**
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* Return the low byte of y coordinate.
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*/
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uint8_t getY() const { return lpy; }
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/**
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* Retrigger lightpen on vertical blank.
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*
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* @param lineCycle current line cycle
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* @param rasterY current y raster position
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* @return true if an IRQ should be triggered
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*/
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bool retrigger(unsigned int lineCycle, unsigned int rasterY)
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{
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const bool triggered = trigger(lineCycle, rasterY);
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switch (cyclesPerLine)
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{
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case 63:
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default:
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lpx = 0xd1;
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break;
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case 65:
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lpx = 0xd5;
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break;
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}
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return triggered;
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}
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/**
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* Trigger lightpen from CIA.
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*
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* @param lineCycle current line cycle
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* @param rasterY current y raster position
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* @return true if an IRQ should be triggered
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*/
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bool trigger(unsigned int lineCycle, unsigned int rasterY)
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{
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if (!isTriggered)
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{
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// don't trigger on the last line, except on the first cycle
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if ((rasterY == lastLine) && (lineCycle > 0)) {
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return false;
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}
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isTriggered = true;
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// Latch current coordinates
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lpx = (lineCycle << 2) + 2;
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lpy = rasterY;
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return true;
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}
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return false;
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}
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/**
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* Untrigger lightpen from CIA.
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*/
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void untrigger() { isTriggered = false; }
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};
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}
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#endif
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