AP_Menu: added check_for_input() API

this allows for async use of the menus, so that a main loop can run
while allowing the user to enter menu commands

libraries/AP_Menu/AP_Menu.cpp

@@ -37,16 +37,129 @@ Menu::Menu(const prog_char *prompt, const Menu::command *commands, uint8_t entri
     _argv = NULL;
 }
 
+/**
+   check for another input byte on the port and accumulate
+   return true if we have a full line ready to process
+ */
+bool
+Menu::_check_for_input(void)
+{
+    if (_port->available() <= 0) {
+        return false;
+    }
+
+    // loop reading characters from the input
+    int c = _port->read();
+
+    // carriage return -> process command
+    if ('\r' == c || '\n' == c) {
+        _inbuf[_input_len] = '\0';
+        _port->write('\r');
+        _port->write('\n');
+        // we have a full line to process
+        return true;
+    }
+
+    // backspace
+    if ('\b' == c) {
+        if (_input_len > 0) {
+            _input_len--;
+            _port->write('\b');
+            _port->write(' ');
+            _port->write('\b');
+            return false;
+        }
+    }
+
+    // printable character
+    if (isprint(c) && (_input_len < (_commandline_max - 1))) {
+        _inbuf[_input_len++] = c;
+        _port->write((char)c);
+    }
+
+    return false;
+}
+
+
+// run the menu
+bool
+Menu::_run_command(void)
+{
+    int8_t ret;
+    uint8_t i;
+    uint8_t argc;
+    char *s = NULL;
+
+    _input_len = 0;
+
+    // split the input line into tokens
+    argc = 0;
+    s = NULL;
+    _argv[argc++].str = strtok_r(_inbuf, " ", &s);
+
+    // XXX should an empty line by itself back out of the current menu?
+    while (argc <= _args_max) {
+        _argv[argc].str = strtok_r(NULL, " ", &s);
+        if ('\0' == _argv[argc].str)
+            break;
+        _argv[argc].i = atol(_argv[argc].str);
+        _argv[argc].f = atof(_argv[argc].str);      // calls strtod, > 700B !
+        argc++;
+    }
+    
+    if (_argv[0].str == NULL) {
+        // we got a blank line, re-display the prompt
+        _port->printf_P(PSTR("%S] "), FPSTR(_prompt));
+        return false;
+    }
+    
+    // populate arguments that have not been specified with "" and 0
+    // this is safer than NULL in the case where commands may look
+    // without testing argc
+    i = argc;
+    while (i <= _args_max) {
+        _argv[i].str = "";
+        _argv[i].i = 0;
+        _argv[i].f = 0;
+        i++;
+    }
+    
+    bool cmd_found = false;
+    // look for a command matching the first word (note that it may be empty)
+    for (i = 0; i < _entries; i++) {
+        if (!strcasecmp_P(_argv[0].str, _commands[i].command)) {
+            ret = _call(i, argc);
+            cmd_found=true;
+            if (-2 == ret)
+                return true;
+            break;
+        }
+    }
+    
+    // implicit commands
+    if (i == _entries) {
+        if (!strcmp(_argv[0].str, "?") || (!strcasecmp_P(_argv[0].str, PSTR("help")))) {
+            _help();
+            cmd_found=true;
+        } else if (!strcasecmp_P(_argv[0].str, PSTR("exit"))) {
+            // exit the menu
+            return true;
+        }
+    }
+
+    if (cmd_found==false)
+    {
+        _port->println_P(PSTR("Invalid command, type 'help'"));
+    }
+
+    return false;
+}
+
+
 // run the menu
 void
 Menu::run(void)
 {
-    int8_t ret;
-    uint8_t len, i;
-    uint8_t argc;
-    int c;
-    char *s = NULL;
-
 	if (_port == NULL) {
 		// default to main serial port
 		_port = hal.console;
@@ -62,96 +175,37 @@ Menu::run(void)
             return;
 
         // loop reading characters from the input
-        len = 0;
+        _input_len = 0;
         _port->printf_P(PSTR("%S] "), FPSTR(_prompt));
+
         for (;; ) {
-            c = _port->read();
+            if (_check_for_input()) {
-            if (-1 == c) {
+                break;
+            }
             hal.scheduler->delay(20);
-                continue;
-            }
-            // carriage return -> process command
-            if ('\r' == c || '\n' == c) {
-                _inbuf[len] = '\0';
-                _port->write('\r');
-                _port->write('\n');
-                break;
-            }
-            // backspace
-            if ('\b' == c) {
-                if (len > 0) {
-                    len--;
-                    _port->write('\b');
-                    _port->write(' ');
-                    _port->write('\b');
-                    continue;
-                }
-            }
-            // printable character
-            if (isprint(c) && (len < (MENU_COMMANDLINE_MAX - 1))) {
-                _inbuf[len++] = c;
-                _port->write((char)c);
-                continue;
-            }
         }
 
-        // split the input line into tokens
+        // we have a full command to run
-        argc = 0;
+        if (_run_command()) break;
-		s = NULL;
+    }    
-        _argv[argc++].str = strtok_r(_inbuf, " ", &s);
+}
-        // XXX should an empty line by itself back out of the current menu?
+
-        while (argc <= MENU_ARGS_MAX) {
+// check for new user input
-            _argv[argc].str = strtok_r(NULL, " ", &s);
+bool
-            if ('\0' == _argv[argc].str)
+Menu::check_input(void)
-                break;
+{
-            _argv[argc].i = atol(_argv[argc].str);
+	if (_port == NULL) {
-            _argv[argc].f = atof(_argv[argc].str);      // calls strtod, > 700B !
+		// default to main serial port
-            argc++;
+		_port = hal.console;
 	}
 
-        if (_argv[0].str == NULL) {
+    _allocate_buffers();
-            continue;
+
+    if (_check_for_input()) {
+        return _run_command();
     }    
 
-        // populate arguments that have not been specified with "" and 0
+    return false;
-        // this is safer than NULL in the case where commands may look
-        // without testing argc
-        i = argc;
-        while (i <= MENU_ARGS_MAX) {
-            _argv[i].str = "";
-            _argv[i].i = 0;
-            _argv[i].f = 0;
-            i++;
-        }
-
-        bool cmd_found = false;
-        // look for a command matching the first word (note that it may be empty)
-        for (i = 0; i < _entries; i++) {
-            if (!strcasecmp_P(_argv[0].str, _commands[i].command)) {
-                ret = _call(i, argc);
-                cmd_found=true;
-                if (-2 == ret)
-                    return;
-                break;
-            }
-        }
-
-        // implicit commands
-        if (i == _entries) {
-            if (!strcmp(_argv[0].str, "?") || (!strcasecmp_P(_argv[0].str, PSTR("help")))) {
-                _help();
-                cmd_found=true;
-            } else if (!strcasecmp_P(_argv[0].str, PSTR("exit"))) {
-                return;
-            }
-        }
-
-        if (cmd_found==false)
-        {
-            _port->println_P(PSTR("Invalid command, type 'help'"));
-        }
-
-    }
 }
 
 // display the list of commands in response to the 'help' command

libraries/AP_Menu/AP_Menu.h

@@ -109,6 +109,11 @@ public:
     /// menu runner
     void        run(void);
 
+    /// check for new input on the port. Can be used
+    /// to allow for the menu to operate asynchronously
+    /// this will return true if the user asked to exit the menu
+    bool        check_input(void);
+
 private:
     /// Implements the default 'help' command.
     ///
@@ -135,6 +140,16 @@ private:
     // allocate inbuf and args buffers
     void _allocate_buffers(void);
 
+    // number of characters read so far from the port
+    uint8_t                 _input_len;
+
+    // check for next input character
+    bool                    _check_for_input(void);
+
+    // run one full entered command. 
+    // return true if the menu loop should exit
+    bool                    _run_command(void);
+    
 	// port to run on
 	static AP_HAL::BetterStream  *_port;
 };