From bba46296b1324fd97e8526e84b3e3087cb0828ac Mon Sep 17 00:00:00 2001
From: Pablo Rodriguez <prodriguez@noreply.git.rodlop.net>
Date: Sat, 15 Mar 2025 01:58:27 -0400
Subject: [PATCH] implemented keypad

---
 CMakeLists.txt  |  2 +-
 Interpreter.cpp | 26 +++++++++++++++++++++++++-
 KeypadSDL.cpp   | 36 ++++++++++++++++++++++++++++++++++++
 KeypadSDL.hpp   | 12 ++++++++++++
 Peripherals.hpp |  7 ++++---
 main.cpp        | 13 +++++--------
 6 files changed, 83 insertions(+), 13 deletions(-)
 create mode 100644 KeypadSDL.cpp
 create mode 100644 KeypadSDL.hpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 39ff7f8..ac6e774 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,5 +5,5 @@ SET(CMAKE_BUILD_TYPE Debug)
 add_subdirectory(submodules/sdl2)
 
 SET(CMAKE_EXPORT_COMPILE_COMMANDS ON)
-add_executable(chocochip8 main.cpp Interpreter.cpp DisplaySDL.cpp BuzzerSDL.cpp CountdownTimerSDL.cpp)
+add_executable(chocochip8 main.cpp Interpreter.cpp DisplaySDL.cpp BuzzerSDL.cpp CountdownTimerSDL.cpp KeypadSDL.cpp)
 target_link_libraries(chocochip8 SDL2::SDL2-static)
diff --git a/Interpreter.cpp b/Interpreter.cpp
index 248ccdd..eaa7173 100644
--- a/Interpreter.cpp
+++ b/Interpreter.cpp
@@ -139,13 +139,37 @@ void Interpreter::tick() {
   case 0xD000: // DXYN - draw
     executeDraw(mvReg[iRegDst], mvReg[iRegSrc], opcode);
     break;
-  case 0xE000: // EX9E, EXA1 - keypad access
+  case 0xE000: // keypad access
+    switch(inst & 0xF0FF) {
+    case 0xE09E: // EX9E - skip if key pressed
+      if(mrKeypad.isKeyPressed(mvReg[iRegDst])) {
+        mvSpecialReg[SR_PC] += 2;
+      }
+      break;
+    case 0xE0A1: // EXA1 - skip if key not pressed
+      if(!mrKeypad.isKeyPressed(mvReg[iRegDst])) {
+        mvSpecialReg[SR_PC] += 2;
+      }
+      break;
+    default:
+      throw std::invalid_argument("not implemented");
+      break;
+    }
     break;
   case 0xF000: // several unique instructions
     switch(inst & 0xF0FF) {
     case 0xF007: // FX07 - read timer register
       mvReg[iRegDst] = mrDelayTimer.get();
       break;
+    case 0xF00A: // FX0A - wait for a keypress
+      mvSpecialReg[SR_PC] -= 2;
+      for(int i = KEY_0; i < KEY_0 + KEY_COUNT; i++) {
+        if(mrKeypad.isKeyPressed(i)) {
+          mvSpecialReg[SR_PC] += 2;
+          break;
+        }
+      }
+      break;
     case 0xF015: // FX15 - set timer register
       mrDelayTimer.set(mvReg[iRegDst]);
       break;
diff --git a/KeypadSDL.cpp b/KeypadSDL.cpp
new file mode 100644
index 0000000..9353880
--- /dev/null
+++ b/KeypadSDL.cpp
@@ -0,0 +1,36 @@
+#include "KeypadSDL.hpp"
+
+bool KeypadSDL::isKeyPressed(int key) const {
+  return mvKeyDown.at(key);
+}
+
+void KeypadSDL::processEvent(SDL_Event &e) {
+  auto keymap = [](int sdlKeyCode) -> int {
+    switch(sdlKeyCode) {
+      case SDLK_1: return chocochip8::KEY_1;
+      case SDLK_2: return chocochip8::KEY_2;
+      case SDLK_3: return chocochip8::KEY_3; 
+      case SDLK_4: return chocochip8::KEY_C;
+      case SDLK_q: return chocochip8::KEY_4;
+      case SDLK_w: return chocochip8::KEY_5;
+      case SDLK_e: return chocochip8::KEY_6;
+      case SDLK_r: return chocochip8::KEY_D;
+      case SDLK_a: return chocochip8::KEY_7;
+      case SDLK_s: return chocochip8::KEY_8;
+      case SDLK_d: return chocochip8::KEY_9;
+      case SDLK_f: return chocochip8::KEY_E;
+      case SDLK_z: return chocochip8::KEY_A;
+      case SDLK_x: return chocochip8::KEY_0;
+      case SDLK_c: return chocochip8::KEY_B;
+      case SDLK_v: return chocochip8::KEY_F;
+      default    : return -1;
+    }
+  };
+
+  if(e.type == SDL_KEYUP || e.type == SDL_KEYDOWN) {
+    int k = keymap(e.key.keysym.sym);
+    if(k != -1) {
+      mvKeyDown[k] = (e.type == SDL_KEYDOWN);
+    }
+  }
+}
diff --git a/KeypadSDL.hpp b/KeypadSDL.hpp
new file mode 100644
index 0000000..37ec9e0
--- /dev/null
+++ b/KeypadSDL.hpp
@@ -0,0 +1,12 @@
+#include "Peripherals.hpp"
+
+#include <SDL2/SDL_events.h>
+#include <array>
+
+class KeypadSDL : public chocochip8::Keypad {
+public:
+  bool isKeyPressed(int key) const override;
+  void processEvent(SDL_Event &e);
+private:
+  std::array<bool, chocochip8::KEY_COUNT> mvKeyDown;
+};
diff --git a/Peripherals.hpp b/Peripherals.hpp
index 657e1d6..2d04ba6 100644
--- a/Peripherals.hpp
+++ b/Peripherals.hpp
@@ -8,11 +8,12 @@ namespace chocochip8 {
   constexpr size_t gcHeight = 64;
   using Scanline = std::bitset<gcWidth>;
 
-  enum class Key {
+  enum {
     KEY_0, KEY_1, KEY_2, KEY_3,
     KEY_4, KEY_5, KEY_6, KEY_7,
     KEY_8, KEY_9, KEY_A, KEY_B,
-    KEY_C, KEY_D, KEY_E, KEY_F
+    KEY_C, KEY_D, KEY_E, KEY_F,
+    KEY_COUNT
   };
 
   class Display {
@@ -32,7 +33,7 @@ namespace chocochip8 {
   class Keypad {
   public:
     virtual ~Keypad() = default;
-    virtual bool isKeyPressed(Key key) = 0;
+    virtual bool isKeyPressed(int key) const = 0;
   };
 
   class CountdownTimer {
diff --git a/main.cpp b/main.cpp
index 760fc9c..ca11992 100644
--- a/main.cpp
+++ b/main.cpp
@@ -8,9 +8,8 @@
 #include "BuzzerSDL.hpp"
 #include "CountdownTimerSDL.hpp"
 #include "DisplaySDL.hpp"
+#include "KeypadSDL.hpp"
 #include "Interpreter.hpp"
-#include "Peripherals.hpp"
-#include "SDL2/SDL_events.h"
 
 int main(int argc, char* argv[]) {
   if (SDL_Init(SDL_INIT_EVERYTHING) < 0) {
@@ -18,17 +17,13 @@ int main(int argc, char* argv[]) {
     return 1;
   }
 
-  class TestKeypad : public chocochip8::Keypad {
-    bool isKeyPressed(chocochip8::Key) override { return false; }
-  };
-
   BuzzerSDL buzzer(440);
   int N = 4;
   DisplaySDL display(128*N, 64*N);
-  TestKeypad keypad;
+  KeypadSDL keypad;
   CountdownTimerSDL delayTimer(60);
   CountdownTimerSDL soundTimer(60);
-  CountdownTimerSDL displayTimer(20);
+  CountdownTimerSDL displayTimer(60);
   chocochip8::Interpreter chip8(display, buzzer, keypad, delayTimer, soundTimer);
 
   auto rom = std::vector<char>();
@@ -46,6 +41,8 @@ int main(int argc, char* argv[]) {
     while(SDL_PollEvent(&event)) {
       if(event.type == SDL_QUIT) {
         done = true;
+      } else {
+        keypad.processEvent(event);
       }
     }
     chip8.tick();