gistfile1.cpp

#include <WProgram.h>
#include <usb_serial.h>
#include <usb_joystick.h>

#include <joystick-input.h>


int main() {
  pinMode(13, OUTPUT);
  Joystick.useManualSend(true);
  while (true) {
    UpdateJoystickState();
    // Convert the signed representation into the unsigned representation expected by teensy
    Joystick.axis(0, (CurrentJoystickState.Axes[0] + 0x8000) & 0xffff);
    Joystick.axis(1, (CurrentJoystickState.Axes[1] + 0x8000) & 0xffff);
    Joystick.axis(2, (CurrentJoystickState.Axes[2] + 0x8000) & 0xffff);
    Joystick.axis(3, (CurrentJoystickState.Axes[3] + 0x8000) & 0xffff);
    for(unsigned i = 0; i < JoystickState::NumButtonBytes * 8; ++i)
      Joystick.button(i, GetJoystickButton(CurrentJoystickState, i));  
    Joystick.send_now();

    if (GetJoystickButton(CurrentJoystickState, 7)){
      digitalWriteFast(13, HIGH);
    }
    else{
      digitalWriteFast(13, LOW);
    }
  }
}

/////////////////////////////////////////////////////////
// joystick-input.cpp
/////////////////////////////////////////////////////////

#include <joystick-input.h>

#include <usb_serial.h>

bool GetJoystickButton(const JoystickState &js, uint8_t button_index) {
  return js.ButtonBytes[button_index / 8] & (1 << (button_index % 8));
}

JoystickState CurrentJoystickState = {0};

void DecodeJoystick(const uint8_t *buffer, JoystickState &state_out) {
  // This is all quite nasty, todo use a stream class
  const uint32_t magic = *reinterpret_cast<const uint32_t *>(buffer + 0);
  const uint8_t num_axes = buffer[5];
  const uint8_t num_buttons_bytes = (buffer[6] + 7) / 8;
  const int16_t *axes = reinterpret_cast<const int16_t *>(buffer + 7);
  const uint8_t *button_bytes =
      reinterpret_cast<const uint8_t *>(buffer + 7 + num_axes * 2);
  memset(&state_out, 0, sizeof(state_out));
  for (uint32_t i = 0; i < JoystickState::NumAxes && i < num_axes; ++i)
    state_out.Axes[i] = axes[i];
  for (uint32_t i = 0;
       i < JoystickState::NumButtonBytes && i < num_buttons_bytes; ++i)
    state_out.ButtonBytes[i] = button_bytes[i];
}

bool UpdateJoystickState() {
  const uint32_t buffer_size = 64;
  static uint8_t buffer[buffer_size];
  static uint32_t bytes_read = 0;
  while (Serial.available() && bytes_read < buffer_size)
  {
    //buffer[bytes_read++] = Serial.read();
    Serial.readBytes(reinterpret_cast<char*>(buffer), buffer_size);
    bytes_read = 64;
  }

  if (bytes_read != buffer_size)
    return false;

  bytes_read = 0;
  DecodeJoystick(buffer, CurrentJoystickState);

  // This runs the risk of missing events which happen for less than a frame It
  // might be worth ORing the buttons together, to catch short presses at the
  // expense of missing out on short releases...
  //while (UpdateJoystickState()) {
  //}
  return true;
}