From aeab98baaf21317d0dc91a5bfde8efb2fbd7998c Mon Sep 17 00:00:00 2001
From: Colby <colby@taplaboratories.com.au>
Date: Tue, 2 Aug 2016 23:44:46 +1000
Subject: [PATCH] add support for the joypad

---
 lib/waterfoul.rb          |  1 +
 lib/waterfoul/emulator.rb |  6 +++-
 lib/waterfoul/input.rb    | 65 +++++++++++++++++++++++++++++++++++++++
 lib/waterfoul/mmu.rb      |  5 +--
 lib/waterfoul/screen.rb   |  2 --
 5 files changed, 74 insertions(+), 5 deletions(-)
 create mode 100644 lib/waterfoul/input.rb

diff --git a/lib/waterfoul.rb b/lib/waterfoul.rb
index 7acc8ec..0187aec 100644
--- a/lib/waterfoul.rb
+++ b/lib/waterfoul.rb
@@ -12,6 +12,7 @@ require "waterfoul/screen"
 require "waterfoul/gpu"
 require "waterfoul/cartridge"
 require "waterfoul/emulator"
+require "waterfoul/input"
 require "byebug"
 
 module Waterfoul
diff --git a/lib/waterfoul/emulator.rb b/lib/waterfoul/emulator.rb
index b480d2a..2a96186 100644
--- a/lib/waterfoul/emulator.rb
+++ b/lib/waterfoul/emulator.rb
@@ -1,7 +1,9 @@
-require 'pp'
+require 'sdl2'
+
 module Waterfoul
   class Emulator
     def initialize(rom_filename, options = {})
+      SDL2.init SDL2::INIT_EVERYTHING
       # read the rom into host memory
       rom = read_program(rom_filename).bytes
       # initialize emulated CPU, GPU & Sound components
@@ -12,6 +14,7 @@ module Waterfoul
       cpu = CPU.new
       @cpu = options.has_key?('skip_boot') ? SkipBoot.set_state(cpu) : cpu
       @gpu = GPU.new
+      @input = Input.new
       @screen = Screen.new
       # @sound = Sound.new
     end
@@ -21,6 +24,7 @@ module Waterfoul
         @cpu.step
         @gpu.step @cpu.m
         @screen.render @gpu.framebuffer if @gpu.vblank?
+        @input.step @cpu.m
         # @sound.step
       end
     end
diff --git a/lib/waterfoul/input.rb b/lib/waterfoul/input.rb
new file mode 100644
index 0000000..248f5d3
--- /dev/null
+++ b/lib/waterfoul/input.rb
@@ -0,0 +1,65 @@
+require 'sdl2'
+
+module Waterfoul
+  class Input
+
+    UP_INPUT_KEYCODE = 82
+    DOWN_INPUT_KEYCODE = 81
+    LEFT_INPUT_KEYCODE = 80
+    RIGHT_INPUT_KEYCODE = 79
+    A_INPUT_KEYCODE = 4
+    B_INPUT_KEYCODE = 5
+    START_INPUT_KEYCODE = 40
+    SELECT_INPUT_KEYCODE = 229
+    POLL_RATE = 65536
+
+    def initialize
+      @modeclock = 0
+      @current_key = 0
+      $mmu.write_byte 0xFF00, 0x3F, hardware_operation: true
+    end
+
+    def step(cycles = 1)
+      @modeclock =+ cycles
+      event = SDL2::Event.poll
+      if @modeclock >= POLL_RATE
+        @modeclock -= POLL_RATE
+
+        return unless @current_key > 0
+        joypad_byte = $mmu.read_byte 0xFF00
+        key_byte = 0x3F
+
+        if joypad_byte & 0x10 == 0x00
+          case @current_key
+          when UP_INPUT_KEYCODE
+            key_byte ^= 0x4
+          when DOWN_INPUT_KEYCODE
+            key_byte ^= 0x8
+          when RIGHT_INPUT_KEYCODE
+            key_byte ^= 0x1
+          when LEFT_INPUT_KEYCODE
+            key_byte ^= 0x2
+          end
+          p "bar!"
+        elsif joypad_byte & 0x20 == 0x00
+          case @current_key
+          when A_INPUT_KEYCODE
+            key_byte ^= 0x1
+          when B_INPUT_KEYCODE
+            key_byte ^= 0x2
+          when START_INPUT_KEYCODE
+            key_byte ^= 0x8
+          when SELECT_INPUT_KEYCODE
+            key_byte ^= 0x4
+          end
+          p "foo!"
+        end
+
+        $mmu.write_byte 0xFF00, (joypad_byte & key_byte), hardware_operation: true
+        Interrupt.request_interrupt Interrupt::INTERRUPT_JOYPAD
+      elsif event.kind_of? SDL2::Event::KeyDown
+        @current_key = event.scancode
+      end
+    end
+  end
+end
diff --git a/lib/waterfoul/mmu.rb b/lib/waterfoul/mmu.rb
index 6b01046..765b044 100644
--- a/lib/waterfoul/mmu.rb
+++ b/lib/waterfoul/mmu.rb
@@ -35,8 +35,6 @@ module Waterfoul
       raise MemoryOutOfBounds if i > MEMORY_SIZE || i < 0
 
       case i
-      when 0xFF00
-        0xFF
       when 0x0000...0x8000 # ROM Bank 0 + n
         if @map_boot_rom && i <= BOOT_ROM_END_MEM_LOC
           BootROM[i]
@@ -68,6 +66,9 @@ module Waterfoul
         case i
         when UNMAP_BOOT_ROM_MEM_LOC # unmap the boot rom when 0xFF50 is wrtiten to in memory
           @map_boot_rom = false if v == 0x1 && @map_boot_rom
+        when 0xFF00
+          current = self[0xFF00]
+          @memory[0xFF00] = (current & 0xF) | (v & 0x30)
         when 0xFF46 # DMA transfer
           dma_transfer v
           @memory[i] = v
diff --git a/lib/waterfoul/screen.rb b/lib/waterfoul/screen.rb
index 68da993..e5d3c95 100644
--- a/lib/waterfoul/screen.rb
+++ b/lib/waterfoul/screen.rb
@@ -1,4 +1,3 @@
-require 'sdl2'
 require 'waterfoul/io/lcd_status'
 
 module Waterfoul
@@ -15,7 +14,6 @@ module Waterfoul
     }
 
     def initialize
-      SDL2.init SDL2::INIT_VIDEO
       @screen = SDL2::Window.create('main', 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, 0)
       @renderer = @screen.create_renderer 1, 0
       @lcd_status = IO::LCDStatus.new