add debug.isGDBConnected()

TeensyDebug.h

@@ -74,6 +74,7 @@ int hcdebug_setBreakpoint(int n);
 size_t gdb_out_write(const uint8_t *msg, size_t len);
 int gdb_file_io(const char *msg);
 extern int file_io_errno;
+extern int gdb_active_flag;
 
 #define O_CREAT         0x200
 #define O_APPEND        8
@@ -117,6 +118,7 @@ public:
   uint32_t getRegister(const char *reg);
   int setRegister(const char *reg, uint32_t value);
   int restoreRunMode();
+  int isGDBConnected() { return gdb_active_flag; }
 
   virtual size_t write(uint8_t b) { 
     return write(&b, 1);

gdbstub.cpp

@@ -953,6 +953,8 @@ int process_k(const char *cmd, char *result) {
   return 0;
 }
 
+int gdb_active_flag = 0;
+
 /**
  * @brief Process a command by calling appropriate delegation function
  * 
@@ -961,6 +963,7 @@ int process_k(const char *cmd, char *result) {
  * @return int 0
  */
 int processCommand(const char *cmd, char *result) {
+  gdb_active_flag = 1;
   switch(cmd[0]) {
     case 'g': return process_g(cmd, result);
     case 'G': return process_G(cmd, result);