Make arducontrol interface asynchronous again

Blocking the main loop for extended periods of time (as could previously
happen with an incomplete packet) is bad, because it prevents the monitor
from triggering overcurrent shutdown.

diff --git a/arducontrol/interface.c b/arducontrol/interface.c
index 1cc4b15fa77a1af3c9f3eae71a2a49dbf5144f89..c5a7262d4c12199b217f0430f5ffe288c399afe6 100644 (file)
--- a/arducontrol/interface.c
+++ b/arducontrol/interface.c
@@ -6,6 +6,10 @@
 #include "serial.h"
 #include "s88.h"
 
+static uint8_t cmd_buffer[15];
+static uint8_t cmd_length = 0;
+static uint8_t cmd_read_pos = 0;
+
 uint8_t dispatch_command(const uint8_t *, uint8_t);
 
 void interface_init(void)
@@ -17,27 +21,42 @@ void interface_init(void)
 
 void interface_check(void)
 {
+       uint8_t count;
        if(serial_read_overrun())
                interface_send1(RECEIVE_OVERRUN);
 
-       while(serial_read_available())
+       count = serial_read_available();
+       if(count>0)
        {
-               uint8_t length = ~serial_read();
+               if(cmd_length==0)
+               {
+                       uint8_t l = ~serial_read();
+                       if(l==0)
+                               serial_write(0xFF);
+                       else if(l>=0x10)
+                               interface_send1(FRAMING_ERROR);
+                       else
+                       {
+                               cmd_length = l;
+                               --count;
+                               cmd_read_pos = 0;
+                       }
+               }
 
-               if(length==0)
-                       serial_write(0xFF);
-               else if(length>=0x10)
-                       interface_send1(FRAMING_ERROR);
-               else
+               if(cmd_read_pos<cmd_length)
                {
-                       uint8_t cmd[15];
                        uint8_t i;
+                       if(cmd_read_pos+count>cmd_length)
+                               count = cmd_length-cmd_read_pos;
+                       for(i=0; i<count; ++i)
+                               cmd_buffer[cmd_read_pos++] = serial_read();
 
-                       for(i=0; i<length; ++i)
-                               cmd[i] = serial_read();
-
-                       uint8_t result = dispatch_command(cmd, length);
-                       interface_send1(result);
+                       if(cmd_read_pos>=cmd_length)
+                       {
+                               uint8_t result = dispatch_command(cmd_buffer, cmd_length);
+                               interface_send1(result);
+                               cmd_length = 0;
+                       }
                }
        }
 }