Tools/mavlink_shell.py: implement a simple shell with history

Tools/mavlink_shell.py

@@ -9,6 +9,7 @@ Open a shell over MAVLink.
 
 from __future__ import print_function
 import sys, select
+import termios
 
 try:
     from pymavlink import mavutil
@@ -118,24 +119,72 @@ def main():
 
     mav_serialport.write('\n') # make sure the shell is started
 
+    # setup the console, so we can read one char at a time
+    fd_in = sys.stdin.fileno()
+    old_attr = termios.tcgetattr(fd_in)
+    new_attr = termios.tcgetattr(fd_in)
+    new_attr[3] = new_attr[3] & ~termios.ECHO # lflags
+    new_attr[3] = new_attr[3] & ~termios.ICANON
+
     try:
+        termios.tcsetattr(fd_in, termios.TCSANOW, new_attr)
+        cur_line = ''
+        command_history = []
+        cur_history_index = 0
+
+        def erase_last_n_chars(N):
+            if N == 0: return
+            CURSOR_BACK_N = '\x1b['+str(N)+'D'
+            ERASE_END_LINE = '\x1b[K'
+            sys.stdout.write(CURSOR_BACK_N + ERASE_END_LINE)
+
         while True:
-            i, o, e = select.select([sys.stdin], [], [], 0.001)
-            if (i):
-                data = sys.stdin.readline()
+            while True:
+                i, o, e = select.select([sys.stdin], [], [], 0)
+                if not i: break
+                ch = sys.stdin.read(1)
 
-                # Erase stdin output (otherwise we have it twice)
-                # FIXME: this assumes a prompt of 5 chars, and does not work in all cases
-                CURSOR_UP_ONE = '\x1b[1A'
-                CURSOR_RIGHT = '\x1b[5C'
-                ERASE_LINE = '\x1b[2K'
-                ERASE_END_LINE = '\x1b[K'
-                sys.stdout.write(CURSOR_UP_ONE + CURSOR_RIGHT + ERASE_END_LINE)
+                # provide a simple shell with command history
+                if ch == '\n':
+                    if len(cur_line) > 0:
+                        # erase current text (mavlink shell will echo it as well)
+                        erase_last_n_chars(len(cur_line))
 
-                # TODO: add a command history?
+                        # add to history
+                        if len(command_history) == 0 or command_history[-1] != cur_line:
+                            command_history.append(cur_line)
+                            if len(command_history) > 50:
+                                del command_history[0]
+                        cur_history_index = len(command_history)
+                    mav_serialport.write(cur_line+'\n')
+                    cur_line = ''
+                elif ord(ch) == 127: # backslash
+                    if len(cur_line) > 0:
+                        erase_last_n_chars(1)
+                        cur_line = cur_line[:-1]
+                        sys.stdout.write(ch)
+                elif ord(ch) == 033:
+                    ch = sys.stdin.read(1) # skip one
+                    ch = sys.stdin.read(1)
+                    if ch == 'A': # arrow up
+                        if cur_history_index > 0:
+                            cur_history_index -= 1
+                    elif ch == 'B': # arrow down
+                        if cur_history_index < len(command_history):
+                            cur_history_index += 1
+                    # TODO: else: support line editing
 
-                #sys.stdout.write(data)
-                mav_serialport.write(data)
+                    erase_last_n_chars(len(cur_line))
+                    if cur_history_index == len(command_history):
+                        cur_line = ''
+                    else:
+                        cur_line = command_history[cur_history_index]
+                    sys.stdout.write(cur_line)
+
+                elif ord(ch) > 3:
+                    cur_line += ch
+                    sys.stdout.write(ch)
+                sys.stdout.flush()
 
             data = mav_serialport.read(4096)
             if data and len(data) > 0:
@@ -148,6 +197,9 @@ def main():
     except KeyboardInterrupt:
         mav_serialport.close()
 
+    finally:
+        termios.tcsetattr(fd_in, termios.TCSADRAIN, old_attr)
+
 
 if __name__ == '__main__':
     main()