Add some controls via the joypad (video mode, 50% scan lines and reset).

Signed-off-by: Andrea Odetti <mariofutire@gmail.com>

linux.md

@@ -97,6 +97,12 @@ There is an initial [libretro](https://docs.libretro.com/development/cores/devel
 
 A retropad can be plugged in port 1 (with or without analog stick).
 
+Keyboard emulation
+
+* ``JOYPAD_R``: equivalent to ``F9`` to cycle video types
+* ``JOYPAD_L``: equivalent to ``CTRL-SHIFT-F6`` to cycle 50% scan lines
+* ``START``: equivalent to ``F2`` to reset the machine
+
 In order to have a better experience with the keyboard, one should probably enable *Game Focus Mode* (normally Scroll-Lock) to disable hotkeys.
 
 Video works, but the vertical flip is done in software.

source/frontends/retro/environment.h

@@ -10,8 +10,10 @@ extern retro_input_state_t input_state_cb;
 extern retro_environment_t environ_cb;
 extern retro_video_refresh_t video_cb;
 extern retro_audio_sample_t audio_cb;
-extern  retro_audio_sample_batch_t audio_batch_cb;
+extern retro_audio_sample_batch_t audio_batch_cb;
 
 extern std::string retro_base_directory;
 
+#define MAX_PADS 1
+
 void display_message(const std::string & message);

source/frontends/retro/game.cpp

@@ -12,13 +12,14 @@
 #include "CPU.h"
 #include "NTSC.h"
 #include "Utilities.h"
+#include "Video.h"
+#include "Interface.h"
 
 #include "linux/keyboard.h"
 #include "linux/paddle.h"
 #include "frontends/common2/programoptions.h"
 #include "frontends/common2/configuration.h"
 #include "frontends/common2/utils.h"
-#include "frontends/retro/environment.h"
 
 #include "libretro.h"
 
@@ -43,10 +44,18 @@ namespace
     }
   }
 
+  void updateWindowTitle()
+  {
+    GetAppleWindowTitle();
+    display_message(g_pAppTitle.c_str());
+  }
+
 }
 
+unsigned Game::input_devices[MAX_PADS] = {0};
+
 Game::Game()
-  : mySpeed(true)
+  : mySpeed(true), myButtonStates(RETRO_DEVICE_ID_JOYPAD_R3 + 1)
 {
   EmulatorOptions options;
   options.memclear = g_nMemoryClearType;
@@ -87,6 +96,7 @@ void Game::executeOneFrame()
 void Game::processInputEvents()
 {
   input_poll_cb();
+  keyboardEmulation();
 }
 
 void Game::keyboardCallback(bool down, unsigned keycode, uint32_t character, uint16_t key_modifiers)
@@ -215,6 +225,57 @@ void Game::processKeyUp(unsigned keycode, uint32_t character, uint16_t key_modif
   }
 }
 
+bool Game::checkButtonPressed(unsigned id)
+{
+  // pressed if it is down now, but was up before
+  const int value = input_state_cb(0, RETRO_DEVICE_JOYPAD, 0, id);
+  const bool pressed = (value != 0) && myButtonStates[id] == 0;
+
+  // update to avoid multiple fires
+  myButtonStates[id] = value;
+
+  return pressed;
+}
+
+
+void Game::keyboardEmulation()
+{
+  if (input_devices[0] != RETRO_DEVICE_NONE)
+  {
+    if (checkButtonPressed(RETRO_DEVICE_ID_JOYPAD_R))
+    {
+      g_eVideoType++;
+      if (g_eVideoType >= NUM_VIDEO_MODES)
+	g_eVideoType = 0;
+
+      Config_Save_Video();
+      VideoReinitialize();
+      VideoRedrawScreen();
+      updateWindowTitle();
+    }
+    if (checkButtonPressed(RETRO_DEVICE_ID_JOYPAD_L))
+    {
+      VideoStyle_e videoStyle = GetVideoStyle();
+      videoStyle = VideoStyle_e(videoStyle ^ VS_HALF_SCANLINES);
+
+      SetVideoStyle(videoStyle);
+
+      Config_Save_Video();
+      VideoReinitialize();
+      VideoRedrawScreen();
+      updateWindowTitle();
+    }
+    if (checkButtonPressed(RETRO_DEVICE_ID_JOYPAD_START))
+    {
+      ResetMachineState();
+    }
+  }
+  else
+  {
+    std::fill(myButtonStates.begin(), myButtonStates.end(), 0);
+  }
+}
+
 void Game::drawVideoBuffer()
 {
   // this should not be necessary

source/frontends/retro/game.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include "frontends/common2/speed.h"
+#include "frontends/retro/environment.h"
 
 class Game
 {
@@ -17,6 +18,8 @@ public:
 
   static void keyboardCallback(bool down, unsigned keycode, uint32_t character, uint16_t key_modifiers);
 
+  static unsigned input_devices[MAX_PADS];
+
 private:
   Speed mySpeed;  // fixed speed
   std::vector<uint8_t> myVideoBuffer;
@@ -27,6 +30,10 @@ private:
   size_t myBorderlessWidth;
   size_t myBorderlessHeight;
 
+  std::vector<int> myButtonStates;
+
+  bool checkButtonPressed(unsigned id);
+  void keyboardEmulation();
 
   static void processKeyDown(unsigned keycode, uint32_t character, uint16_t key_modifiers);
   static void processKeyUp(unsigned keycode, uint32_t character, uint16_t key_modifiers);

source/frontends/retro/libretro.cpp

@@ -61,6 +61,8 @@ void retro_set_controller_port_device(unsigned port, unsigned device)
     default:
       break;
     }
+
+    Game::input_devices[port] = device;
   }
 }