From 44cdad61e0484b42477c0ddf9b1cee21bc01aaf1 Mon Sep 17 00:00:00 2001
From: Kevin Larke <kevin@larke.org>
Date: Sun, 8 Feb 2015 08:54:53 -0800
Subject: [PATCH] cmKeyboard.h/c : Added cmIsKeyWaiting().

---
 cmKeyboard.c | 34 ++++++++++++++++++++++++++++++++++
 cmKeyboard.h | 29 +++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/cmKeyboard.c b/cmKeyboard.c
index f5b20d6..b065ec3 100644
--- a/cmKeyboard.c
+++ b/cmKeyboard.c
@@ -233,3 +233,37 @@ void testKb2()
 
   reset_keypress();
 }
+
+
+// Based on: // From: http://www.flipcode.com/archives/_kbhit_for_Linux.shtml
+
+int cmIsKeyWaiting()
+{
+  static const int STDIN       = 0;
+  static bool      initialized = false;
+  struct timeval   timeout;
+  fd_set           rdset;
+
+  if (! initialized)
+  {
+    // Use termios to turn off line buffering
+    struct termios term;
+    tcgetattr(STDIN, &term);
+    term.c_lflag &= ~ICANON;
+    tcsetattr(STDIN, TCSANOW, &term);
+    setbuf(stdin, NULL);
+    initialized = true;
+  }
+
+
+  FD_ZERO(&rdset);
+  FD_SET(STDIN, &rdset);
+  timeout.tv_sec  = 0;
+  timeout.tv_usec = 0;
+
+  // time out immediately if STDIN is not ready.
+  return select(STDIN + 1, &rdset, NULL, NULL, &timeout);
+
+}
+
+
diff --git a/cmKeyboard.h b/cmKeyboard.h
index 6d30826..cc2db66 100644
--- a/cmKeyboard.h
+++ b/cmKeyboard.h
@@ -34,4 +34,33 @@ typedef struct
 // Set 'p' to NULL if the value of the key is not required.
 void cmKeyPress( cmKbRecd* p );
 
+
+// Return non-zero if a key is waiting to be read otherwise return 0.
+// Use getchar() to pick up the key.
+// 
+// Example:
+// while( 1 )
+// {
+//    if( cmIsKeyWaiting() == 0 )
+//       usleep(20000);
+//    else
+//    {
+//      char c = getchar();
+//      switch(c)
+//      {
+//        ....
+//      } 
+//    }
+//
+// }
+//
+// TODO: Note that this function turns off line-buffering on stdin.
+// It should be changed to a three function sequence.
+// bool org_state =  cmSetStdinLineBuffering(false);
+// ....
+// cmIsKeyWaiting()
+// ....
+// cmSetStdinLineBuffering(org_state)
+int cmIsKeyWaiting();
+
 #endif