Cleaned up the licensing.

third_party/mozc-morse/dit-dah.c

@@ -0,0 +1,162 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA  02110-1301, USA.
+ */
+
+
+/*
+ * USB keyboard to input by Morse code with help of special romaji table.
+ * The device transmits keycodes based on a single button input:
+ *
+ * "." for a short tap
+ * "-" for a long tap
+ * "/" for a pause after a tap
+ * [SPACE][ENTER] for a long pause after taps (convert and commit)
+ */
+
+#include <avr/io.h>
+#include <avr/wdt.h>
+#include <util/delay.h>     /* for _delay_ms() */
+#include "usb_keyboard.h"
+
+/*
+ * Thresholds for button pressing duration.
+ *
+ * A counter is increased every 10 milliseconds in the main loop.
+ * These time lengths are specified by the units of this counter.
+ *
+ * FYI: WPM = words per minute is commonly used unit of morse code speed.
+ * 1 word stands for 50 dots. For example, 10 WPM means 1 dot=0.12s
+ */
+
+#define T_DIT 12                /* 10WPM */
+
+/* minimum length of button press duration for a "dah" */
+#define THRESHOLD_DIT_DAH (T_DIT + 7)
+
+/* minimum length of time for a character separator */
+#define THRESHOLD_GAP (T_DIT * 3)
+
+/* length of time to wait before convert and commit */
+#define THRESHOLD_LONG_GAP 100  /* 1 second */
+
+
+#define EMPTY 255
+
+int __attribute__((noreturn)) main(void)
+{
+  PORTB = 0xff;
+
+  wdt_enable(WDTO_1S);
+  initUsbKeyboard();
+
+  /* sets up timer for button polling interval */
+  /* timer 1 CTC mode, counts up at f[clock]/8 [Hz] */
+  TCCR1B = (1 << WGM12) | (1 << CS11);
+  TCNT1 = 0;
+  OCR1A = F_CPU / 8 / 100;  /* 100Hz, T=10 milliseconds */
+
+  uchar key = 0;
+
+  /* Keyboard keys to send.
+   * Since we have only 1 byte buffer, the first key is dropped if the second
+   * key is pushed before submitting it.
+   */
+  uchar cmdBuf = EMPTY;
+
+  uchar state = 0;
+  unsigned int count = 0;
+  while(1) {  /* main event loop */
+    wdt_reset();
+    usbPoll();
+    if(usbInterruptIsReady()) {
+      if (cmdBuf != EMPTY) {
+        prepareInterruptReport(cmdBuf);
+        if (cmdBuf == KEYCODE_NONE) {
+          cmdBuf = EMPTY;
+        } else {
+          /* release all keys */
+          cmdBuf = KEYCODE_NONE;
+        }
+      }
+    }
+    /* samples the key input every 10 milliseconds to avoid chattering */
+    if (bit_is_clear(TIFR, OCF1A)) {
+      continue;
+    }
+    TIFR |= _BV(OCF1A);  /* clear OCF1A */
+
+    key = bit_is_clear(PINB, PINB0);
+    switch(state) {
+    case 0:  /* initial state or after a long gap */
+      if (key) {
+        state = 1;
+        count = 0;
+      }
+      break;
+    case 1:  /* key is on */
+      if (!key) {
+        cmdBuf = KEYCODE_PERIOD;  /* dot */
+        state = 3;
+        count = 0;
+        break;
+      }
+      if (count++ > THRESHOLD_DIT_DAH) {
+        state = 2;
+        count = 0;
+      }
+      break;
+    case 2:  /* key has been pressed long enough to input dash */
+      if (!key) {
+        cmdBuf = KEYCODE_HYPHEN;  /* dash */
+        state = 3;
+        count = 0;
+      }
+      break;
+    case 3:  /* key was released. */
+      if (key) {
+        state = 1;
+        count = 0;
+        break;
+      }
+      if (count++ > THRESHOLD_GAP) {
+        cmdBuf = KEYCODE_SLASH;  /* word separator */
+        state = 4;
+      }
+      break;
+    case 4:  /* short gap, or long gap */
+      if (key) {
+        state = 1;
+        count = 0;
+        break;
+      }
+      if (count++ > THRESHOLD_LONG_GAP) {
+        cmdBuf = KEYCODE_SPACE;  /* start conversion */
+        state = 5;
+        count = 0;
+      }
+      break;
+    case 5:  /* long gap. pause before sending Enter key. */
+      if (count++ > T_DIT) {
+        cmdBuf = KEYCODE_ENTER;  /* commit conversion */
+        state = 0;
+        count = 0;
+      }
+      break;
+    }
+  }
+}