libsidplayfp  2.2.2
lightpen.h
1 /*
2  * This file is part of libsidplayfp, a SID player engine.
3  *
4  * Copyright 2011-2020 Leandro Nini <drfiemost@users.sourceforge.net>
5  * Copyright 2009-2014 VICE Project
6  * Copyright 2007-2010 Antti Lankila
7  * Copyright 2001 Simon White
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
22  */
23 
24 #ifndef LIGHTPEN_H
25 #define LIGHTPEN_H
26 
27 namespace libsidplayfp
28 {
29 
34 class Lightpen
35 {
36 private:
38  unsigned int lastLine;
39 
41  unsigned int cyclesPerLine;
42 
44  unsigned int lpx;
45 
47  unsigned int lpy;
48 
50  bool isTriggered;
51 
52 private:
59  uint8_t getXpos(unsigned int lineCycle) const
60  {
61  if (lineCycle < 12)
62  lineCycle += cyclesPerLine-1;
63 
64  lineCycle -= 12;
65 
66  return lineCycle << 2;
67  }
68 
69 public:
76  void setScreenSize(unsigned int height, unsigned int width)
77  {
78  lastLine = height - 1;
79  cyclesPerLine = width;
80  }
81 
85  void reset()
86  {
87  lpx = 0;
88  lpy = 0;
89  isTriggered = false;
90  }
91 
95  uint8_t getX() const { return lpx; }
96 
100  uint8_t getY() const { return lpy; }
101 
109  bool retrigger(unsigned int lineCycle, unsigned int rasterY)
110  {
111  const bool triggered = trigger(lineCycle, rasterY);
112  switch (cyclesPerLine)
113  {
114  case 63:
115  default:
116  lpx = 0xd1;
117  break;
118  case 65:
119  lpx = 0xd5;
120  break;
121  }
122  return triggered;
123  }
124 
132  bool trigger(unsigned int lineCycle, unsigned int rasterY)
133  {
134  if (isTriggered)
135  return false;
136 
137  isTriggered = true;
138 
139  // don't latch on the last line, except on the first cycle
140  if ((rasterY != lastLine) || (lineCycle == 0))
141  {
142  // Latch current coordinates
143  lpx = getXpos(lineCycle) + 2;
144  lpy = rasterY;
145  }
146 
147  return true;
148  }
149 
153  void untrigger() { isTriggered = false; }
154 };
155 
156 }
157 
158 #endif
Definition: lightpen.h:35
uint8_t getX() const
Definition: lightpen.h:95
bool retrigger(unsigned int lineCycle, unsigned int rasterY)
Definition: lightpen.h:109
uint8_t getY() const
Definition: lightpen.h:100
void reset()
Definition: lightpen.h:85
bool trigger(unsigned int lineCycle, unsigned int rasterY)
Definition: lightpen.h:132
void setScreenSize(unsigned int height, unsigned int width)
Definition: lightpen.h:76
void untrigger()
Definition: lightpen.h:153