Increased g-code parser line buffer. Added line overflow feedback.

- Increased g-code parser line buffer from 50 to 70 characters. Should
fix most all issues with long arc statements, provided that they are 8
digits(float) long only.

- Added a line buffer overflow feedback error to let the user know when
it encounters this problem. Resets the line whenever this occurs.
(Thanks @BHSPitMonkey!)

config.h

@@ -185,11 +185,11 @@
 // each of the startup blocks, as they are each stored as a string of this size. Make sure
 // to account for the available EEPROM at the defined memory address in settings.h and for
 // the number of desired startup blocks.
-// NOTE: 50 characters is not a problem except for extreme cases, but the line buffer size 
+// NOTE: 70 characters is not a problem except for extreme cases, but the line buffer size 
 // can be too small and g-code blocks can get truncated. Officially, the g-code standards 
 // support up to 256 characters. In future versions, this default will be increased, when 
 // we know how much extra memory space we can re-invest into this.
-// #define LINE_BUFFER_SIZE 50  // Uncomment to override default in protocol.h
+// #define LINE_BUFFER_SIZE 70  // Uncomment to override default in protocol.h
   
 // Serial send and receive buffer size. The receive buffer is often used as another streaming
 // buffer to store incoming blocks to be processed by Grbl when its ready. Most streaming

protocol.c

@@ -37,10 +37,16 @@ static uint8_t char_counter; // Last character counter in line variable.
 static uint8_t iscomment; // Comment/block delete flag for processor to ignore comment characters.
 
 
-void protocol_init() 
+static void protocol_reset_line_buffer()
 {
   char_counter = 0; // Reset line input
   iscomment = false;
+}
+
+
+void protocol_init() 
+{
+  protocol_reset_line_buffer();
   report_init_message(); // Welcome message   
   
   PINOUT_DDR &= ~(PINOUT_MASK); // Set as input pins
@@ -303,8 +309,7 @@ void protocol_process()
         // Empty or comment line. Skip block.
         report_status_message(STATUS_OK); // Send status message for syncing purposes.
       }
-      char_counter = 0; // Reset line buffer index
-      iscomment = false; // Reset comment flag
+      protocol_reset_line_buffer();      
     
     } else {
       if (iscomment) {
@@ -322,7 +327,9 @@ void protocol_process()
           // Enable comments flag and ignore all characters until ')' or EOL.
           iscomment = true;
         } else if (char_counter >= LINE_BUFFER_SIZE-1) {
-          // Throw away any characters beyond the end of the line buffer          
+          // Report line buffer overflow and reset
+          report_status_message(STATUS_OVERFLOW);
+          protocol_reset_line_buffer();
         } else if (c >= 'a' && c <= 'z') { // Upcase lowercase
           line[char_counter++] = c-'a'+'A';
         } else {

protocol.h

@@ -30,7 +30,7 @@
 // memory space we can invest into here or we re-write the g-code parser not to have his 
 // buffer.
 #ifndef LINE_BUFFER_SIZE
-  #define LINE_BUFFER_SIZE 50
+  #define LINE_BUFFER_SIZE 70
 #endif
 
 // Initialize the serial protocol

report.c

@@ -74,6 +74,8 @@ void report_status_message(uint8_t status_code)
       printPgmString(PSTR("Busy or queued")); break;
       case STATUS_ALARM_LOCK:
       printPgmString(PSTR("Alarm lock")); break;
+      case STATUS_OVERFLOW:
+      printPgmString(PSTR("Line overflow")); break;
     }
     printPgmString(PSTR("\r\n"));
   }

report.h

@@ -35,6 +35,7 @@
 #define STATUS_SETTING_READ_FAIL 10
 #define STATUS_IDLE_ERROR 11
 #define STATUS_ALARM_LOCK 12
+#define STATUS_OVERFLOW 13
 
 // Define Grbl alarm codes. Less than zero to distinguish alarm error from status error.
 #define ALARM_HARD_LIMIT -1