Chatpad.cpp

/*
 * Copyright (C) 2011 Cliff L. Biffle, all rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include "Chatpad.h"
#include "Arduino.h"
#include "HardwareSerial.h"

#include <avr/pgmspace.h>

// Masks for modifier bits
static const byte kShiftMask = (1 << 0);
static const byte kGreenSquareMask = (1 << 1);
static const byte kOrangeCircleMask = (1 << 2);
static const byte kPeopleMask = (1 << 3);

// Voodoo protocol messages
static const byte kInitMessage[] = { 0x87, 0x02, 0x8C, 0x1F, 0xCC };
static const byte kAwakeMessage[] = { 0x87, 0x02, 0x8C, 0x1B, 0xD0 };

void Chatpad::init(HardwareSerial &serial, Chatpad::callback_t callback) {
  _serial = &serial;
  _callback = callback;
  _last_modifiers = 0;
  _last_key0 = 0;
  _last_key1 = 0;
  _last_ping = 0;
  Serial.begin(19200);
  Serial.write(kInitMessage, sizeof(kInitMessage));
//  while(Serial.peek() != 0xA5)
//  {
//   Serial.read();
//   continue;
//  }
}

void Chatpad::poll() {
  // Only act if a full message is available.
  if (Serial.available() >= 8) {
    for (int i = 0; i < 8; i++) {
      _buffer[i] = Serial.read();
    }

    // We expect "status report" packets beginning with 0xA5, but don't know
    // what to do with them -- so we silently discard them.
    if (_buffer[0] == 0xA5) return;

    // We *do not* expect other types of packets.  If we find one, complain
    // to the user.
    if (_buffer[0] != 0xB4) {
      return;
    }
    if (_buffer[1] != 0xC5) {
      return;
    }

    // Check the checksum.
    unsigned char checksum = _buffer[0];
    for (int i = 1; i < 7; i++) checksum += _buffer[i];
    checksum = -checksum;
    if (checksum != _buffer[7]) {
      return;
    }

    // Packet looks good!
    // Dissect the parts we care about:
    byte modifiers = _buffer[3];
    byte key0 = _buffer[4];
    byte key1 = _buffer[5];

    // Check for changes in the modifiers.
    byte modifier_changes = modifiers ^ _last_modifiers;
    if (modifier_changes & kShiftMask) {
      dispatch(KeyShift, modifiers & kShiftMask);
    }
    if (modifier_changes & kGreenSquareMask) {
      dispatch(KeyGreenSquare, modifiers & kGreenSquareMask);
    }
    if (modifier_changes & kOrangeCircleMask) {
      dispatch(KeyOrangeCircle, modifiers & kOrangeCircleMask);
    }
    if (modifier_changes & kPeopleMask) {
      dispatch(KeyPeople, modifiers & kPeopleMask);
    }
    _last_modifiers = modifiers;

    // Check for changes in the other keys
    if (key0 && key0 != _last_key0 && key0 != _last_key1) {
      dispatch(key0, Down);
    }
    if (key1 && key1 != _last_key0 && key1 != _last_key1) {
      dispatch(key1, Down);
    }
    if (_last_key0 && _last_key0 != key0 && _last_key0 != key1) {
      dispatch(_last_key0, Up);
    }
    if (_last_key1 && _last_key1 != key0 && _last_key1 != key1) {
      dispatch(_last_key1, Up);
    }
    _last_key0 = key0;
    _last_key1 = key1;
  }

  uint32_t time = millis();
  if (time - _last_ping > 1000) {
    _last_ping = time;
    Serial.write(kAwakeMessage, sizeof(kAwakeMessage));
  }
}

bool Chatpad::isShiftDown() const {
  return _last_modifiers & kShiftMask;
}

bool Chatpad::isGreenSquareDown() const {
  return _last_modifiers & kGreenSquareMask;
}

bool Chatpad::isOrangeCircleDown() const {
  return _last_modifiers & kOrangeCircleMask;
}

bool Chatpad::isPeopleDown() const {
  return _last_modifiers & kPeopleMask;
}

void Chatpad::dispatch(uint8_t code, int is_down) {
  _callback(*this, (keycode_t) code, is_down? Down : Up);
}

/**************
 * Translation
 */

// These tables have been compacted and must be accessed using this formula:
//  index = (((keycode & 0xF0) - 0x10) >> 1) | ((keycode & 0x0F) - 1)
static const char kAsciiTable[] PROGMEM = {
  '7', /* 11 Key7 */
  '6', /* 12 Key6 */
  '5', /* 13 Key5 */
  '4', /* 14 Key4 */
  '3', /* 15 Key3 */
  '2', /* 16 Key2 */
  '1', /* 17 Key1 */
  0, /* 18 Unused */

  'u', /* 21 KeyU */
  'y', /* 22 KeyY */
  't', /* 23 KeyT */
  'r', /* 24 KeyR */
  'e', /* 25 KeyE */
  'w', /* 26 KeyW */
  'q', /* 27 KeyQ */
  0, /* 28 Unused */

  'j', /* 31 KeyJ */
  'h', /* 32 KeyH */
  'g', /* 33 KeyG */
  'f', /* 34 KeyF */
  'd', /* 35 KeyD */
  's', /* 36 KeyS */
  'a', /* 37 KeyA */
  0, /* 38 Unused */

  'n', /* 41 KeyN */
  'b', /* 42 KeyB */
  'v', /* 43 KeyV */
  'c', /* 44 KeyC */
  'x', /* 45 KeyX */
  'z', /* 46 KeyZ */
  0, /* 47 Unused */
  0, /* 48 Unused */

  0, /* 51 KeyRight */
  'm', /* 52 KeyM */
  '.', /* 53 KeyPeriod */
  ' ', /* 54 KeySpace */
  0, /* 55 KeyLeft */
  0, /* 56 Unused */
  0, /* 57 Unused */
  0, /* 58 Unused */

  0, /* 61 Unused */
  ',', /* 62 KeyComma */
  '\n', /* 63 KeyEnter */
  'p', /* 64 KeyP */
  '0', /* 65 Key0 */
  '9', /* 66 Key9 */
  '8', /* 67 Key8 */
  0, /* 68 Unused */

  '\b', /* 71 KeyBackspace */
  'l', /* 72 KeyL */
  0, /* 73 Unused */
  0, /* 74 Unused */
  'o', /* 75 KeyO */
  'i', /* 76 KeyI */
  'k', /* 77 KeyK */
  0, /* 78 Unused */
};

static const char kAsciiTable_Shifted[] PROGMEM = {
  '&', /* 11 Key7 */
  '^', /* 12 Key6 */
  '%', /* 13 Key5 */
  '$', /* 14 Key4 */
  '#', /* 15 Key3 */
  '@', /* 16 Key2 */
  '!', /* 17 Key1 */
  0, /* 18 Unused */

  'U', /* 21 KeyU */
  'Y', /* 22 KeyY */
  'T', /* 23 KeyT */
  'R', /* 24 KeyR */
  'E', /* 25 KeyE */
  'W', /* 26 KeyW */
  'Q', /* 27 KeyQ */
  0, /* 28 Unused */

  'J', /* 31 KeyJ */
  'H', /* 32 KeyH */
  'G', /* 33 KeyG */
  'F', /* 34 KeyF */
  'D', /* 35 KeyD */
  'S', /* 36 KeyS */
  'A', /* 37 KeyA */
  0, /* 38 Unused */

  'N', /* 41 KeyN */
  'B', /* 42 KeyB */
  'V', /* 43 KeyV */
  'C', /* 44 KeyC */
  'X', /* 45 KeyX */
  'Z', /* 46 KeyZ */
  0, /* 47 Unused */
  0, /* 48 Unused */

  0, /* 51 KeyRight */
  'M', /* 52 KeyM */
  '>', /* 53 KeyPeriod */
  ' ', /* 54 KeySpace */
  0, /* 55 KeyLeft */
  0, /* 56 Unused */
  0, /* 57 Unused */
  0, /* 58 Unused */

  0, /* 61 Unused */
  '<', /* 62 KeyComma */
  '\n', /* 63 KeyEnter */
  'P', /* 64 KeyP */
  ')', /* 65 Key0 */
  '(', /* 66 Key9 */
  '*', /* 67 Key8 */
  0, /* 68 Unused */

  '\b', /* 71 KeyBackspace */
  'L', /* 72 KeyL */
  0, /* 73 Unused */
  0, /* 74 Unused */
  'O', /* 75 KeyO */
  'I', /* 76 KeyI */
  'K', /* 77 KeyK */
  0, /* 78 Unused */
};

char Chatpad::toAscii(keycode_t code) {
  byte index = (((code - 0x11) & 0x70) >> 1) | ((code - 0x11) & 0x7);
  if (index >= sizeof(kAsciiTable)) return 0;

  if (isShiftDown()) {
    return pgm_read_byte_near(kAsciiTable_Shifted + index);
  } else {
    return pgm_read_byte_near(kAsciiTable + index);
  }
}