Input

CMakeLists.txt

@@ -14,6 +14,7 @@ target_sources(
 	Source/CPU/CPU.cpp
 	Source/CPU/AddressModes.cpp
 	Source/CPU/Instructions.cpp
+	Source/Input.cpp
 	Source/NES.cpp
 	Source/Platform.cpp
 	Source/PPU/PPU.cpp

Source/Input.cpp

@@ -0,0 +1,40 @@
+#include "Input.hpp"
+
+
+void Input::Strobe(uint8_t* but)
+{
+	if (strobe)
+	{
+		for (int i = 0; i < 8; ++i)
+		{
+			buttons[i] = but[i];
+		}
+	}
+}
+
+uint8_t Input::Poll()
+{
+	uint8_t buttonState;
+
+	// Strobe set - return state of A button
+	if (strobe)
+	{
+		buttonState = buttons[Buttons::A];
+	}
+
+	// All 8 bits read - return 1u
+	else if (buttonIndex > Buttons::Right)
+	{
+		buttonState = 1u;
+	}
+
+	// Return next bit
+	else
+	{
+		buttonState = buttons[buttonIndex];
+
+		++buttonIndex;
+	}
+
+	return buttonState;
+}

Source/Input.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <cstdint>
+#include <cstdio>
+
+
+enum Buttons
+{
+	A = 0,
+	B = 1,
+	Select = 2,
+	Start = 3,
+	Up = 4,
+	Down = 5,
+	Left = 6,
+	Right = 7
+};
+
+
+class Input
+{
+public:
+	void Strobe(uint8_t* but);
+	uint8_t Poll();
+
+private:
+	friend class NES;
+
+	bool strobe{};
+	uint8_t buttonIndex{};
+	uint8_t buttons[8]{};
+};

Source/NES.cpp

@@ -44,7 +44,8 @@ NES::NES()
 	: cpu(std::make_unique<CPU>()),
 	  ppu(std::make_unique<PPU>()),
 	  cartridge(std::make_unique<Cartridge>()),
-	  platform(std::make_unique<Platform>("NES", WINDOW_WIDTH, WINDOW_HEIGHT, VIDEO_WIDTH, VIDEO_HEIGHT))
+	  platform(std::make_unique<Platform>("NES", WINDOW_WIDTH, WINDOW_HEIGHT, VIDEO_WIDTH, VIDEO_HEIGHT)),
+	  input(std::make_unique<Input>())
 {
 	ppu->nes = this;
 
@@ -123,10 +124,14 @@ void NES::InsertCartridge(char const* filename)
 
 void NES::Run()
 {
-	while (!platform->ProcessInput())
+	uint8_t buttons[8]{};
+
+	while (!platform->ProcessInput(buttons))
 	{
 		cpu->Cycle();
 
+		input->Strobe(buttons);
+
 		uint8_t cpuCyclesTaken = (cpu->cycles - cpu->prevCycles) * 3u;
 
 		ppu->Cycle(cpuCyclesTaken);
@@ -166,6 +171,7 @@ void NES::Write(BusSource source, uint16_t address, uint8_t value)
 			{
 				uint16_t index = address & 0x1Fu;
 
+				// PPU OAM
 				if (index == 0x14u)
 				{
 					uint8_t addrMsb = value;
@@ -177,6 +183,20 @@ void NES::Write(BusSource source, uint16_t address, uint8_t value)
 						ppu->oam[ppu->oamAddr + addrLsb] = Read(BusSource::CPU, addr);
 					}
 				}
+
+				// Controller
+				else if (index == 0x16u)
+				{
+					if (value & 0x1u)
+					{
+						input->strobe = true;
+					}
+					else
+					{
+						input->strobe = false;
+						input->buttonIndex = 0u;
+					}
+				}
 			}
 
 				// Expansion I/O
@@ -253,6 +273,13 @@ uint8_t NES::Read(BusSource source, uint16_t address)
 				// APU and IO
 			else if (address < 0x4020u)
 			{
+				uint16_t index = address & 0x1Fu;
+
+				// Controller
+				if (index == 0x16u)
+				{
+					byte = input->Poll();
+				}
 			}
 
 				// Expansion I/O

Source/NES.hpp

@@ -2,6 +2,7 @@
 
 #include "Cartridge.hpp"
 #include "CPU/CPU.hpp"
+#include "Input.hpp"
 #include "Platform.hpp"
 #include "PPU/PPU.hpp"
 #include <memory>
@@ -45,6 +46,7 @@ public:
 	std::unique_ptr<PPU> ppu;
 	std::unique_ptr<Cartridge> cartridge;
 	std::unique_ptr<Platform> platform;
+	std::unique_ptr<Input> input;
 
 	bool nmi{};
 	Color palette[64];

Source/Platform.cpp

@@ -1,4 +1,5 @@
 #include "Platform.hpp"
+#include "Input.hpp"
 #include <SDL2/SDL.h>
 
 
@@ -30,7 +31,7 @@ void Platform::Update(void const* buffer, int pitch)
 	SDL_RenderPresent(renderer);
 }
 
-bool Platform::ProcessInput()
+bool Platform::ProcessInput(uint8_t* buttons)
 {
 	bool quit = false;
 
@@ -55,6 +56,95 @@ bool Platform::ProcessInput()
 						quit = true;
 						break;
 					}
+					case SDLK_UP:
+					{
+						 {buttons[Buttons::Up] = 1u;}
+						break;
+					}
+					case SDLK_DOWN:
+					{
+						 {buttons[Buttons::Down] = 1u;}
+						break;
+					}
+					case SDLK_LEFT:
+					{
+						 {buttons[Buttons::Left] = 1u;}
+						break;
+					}
+					case SDLK_RIGHT:
+					{
+						 {buttons[Buttons::Right] = 1u;}
+						break;
+					}
+					case SDLK_LSHIFT:
+					{
+						 buttons[Buttons::Select] = 1u;
+						break;
+					}
+					case SDLK_RETURN:
+					{
+						 {buttons[Buttons::Start] = 1u;}
+						break;
+					}
+					case SDLK_z:
+					{
+						 {buttons[Buttons::A] = 1u;}
+						break;
+					}
+					case SDLK_x:
+					{
+						 {buttons[Buttons::B] = 1u;}
+						break;
+					}
+				}
+
+				break;
+			}
+
+			case SDL_KEYUP:
+			{
+				switch (event.key.keysym.sym)
+				{
+					case SDLK_UP:
+					{
+						 {buttons[Buttons::Up] = 0u;}
+						break;
+					}
+					case SDLK_DOWN:
+					{
+						 {buttons[Buttons::Down] = 0u;}
+						break;
+					}
+					case SDLK_LEFT:
+					{
+						 {buttons[Buttons::Left] = 0u;}
+						break;
+					}
+					case SDLK_RIGHT:
+					{
+						 {buttons[Buttons::Right] = 0u;}
+						break;
+					}
+					case SDLK_LSHIFT:
+					{
+						 {buttons[Buttons::Select] = 0u;}
+						break;
+					}
+					case SDLK_RETURN:
+					{
+						 {buttons[Buttons::Start] = 0u;}
+						break;
+					}
+					case SDLK_z:
+					{
+						 {buttons[Buttons::A] = 0u;}
+						break;
+					}
+					case SDLK_x:
+					{
+						 {buttons[Buttons::B] = 0u;}
+						break;
+					}
 				}
 
 				break;
@@ -62,5 +152,6 @@ bool Platform::ProcessInput()
 		}
 	}
 
+
 	return quit;
 }

Source/Platform.hpp

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <cstdint>
+#include "Input.hpp"
 
 
 class SDL_Window;
@@ -14,7 +15,7 @@ public:
 	Platform(char const* title, int windowWidth, int windowHeight, int textureWidth, int textureHeight);
 	~Platform();
 	void Update(void const* buffer, int pitch);
-	bool ProcessInput();
+	bool ProcessInput(uint8_t* buttons);
 
 	SDL_Window* window{};
 	SDL_Renderer* renderer{};