Merge pull request #2095 from thinkyhead/cherry_picking2

Add gcode_line_error to reduce code size

Marlin/Marlin_main.cpp

   lcd_update();
 }
 
+void gcode_line_error(const char *err, bool doFlush=true) {
+  SERIAL_ERROR_START;
+  serialprintPGM(err);
+  SERIAL_ERRORLN(gcode_LastN);
+  //Serial.println(gcode_N);
+  if (doFlush) FlushSerialRequestResend();
+  serial_count = 0;
+}
+
 /**
  * Add to the circular command queue the next command from:
  *  - The command-injection queue (queued_commands_P)
         strchr_pointer = strchr(command, 'N');
         gcode_N = (strtol(strchr_pointer + 1, NULL, 10));
         if (gcode_N != gcode_LastN + 1 && strstr_P(command, PSTR("M110")) == NULL) {
-          SERIAL_ERROR_START;
-          SERIAL_ERRORPGM(MSG_ERR_LINE_NO);
-          SERIAL_ERRORLN(gcode_LastN);
-          //Serial.println(gcode_N);
-          FlushSerialRequestResend();
-          serial_count = 0;
+          gcode_line_error(PSTR(MSG_ERR_LINE_NO));
           return;
         }
 
           strchr_pointer = strchr(command, '*');
 
           if (strtol(strchr_pointer + 1, NULL, 10) != checksum) {
-            SERIAL_ERROR_START;
-            SERIAL_ERRORPGM(MSG_ERR_CHECKSUM_MISMATCH);
-            SERIAL_ERRORLN(gcode_LastN);
-            FlushSerialRequestResend();
-            serial_count = 0;
+            gcode_line_error(PSTR(MSG_ERR_CHECKSUM_MISMATCH));
             return;
           }
-          //if no errors, continue parsing
+          // if no errors, continue parsing
         }
         else {
-          SERIAL_ERROR_START;
-          SERIAL_ERRORPGM(MSG_ERR_NO_CHECKSUM);
-          SERIAL_ERRORLN(gcode_LastN);
-          FlushSerialRequestResend();
-          serial_count = 0;
+          gcode_line_error(PSTR(MSG_ERR_NO_CHECKSUM));
           return;
         }
 
         gcode_LastN = gcode_N;
-        //if no errors, continue parsing
+        // if no errors, continue parsing
       }
       else {  // if we don't receive 'N' but still see '*'
         if ((strchr(command, '*') != NULL)) {
-          SERIAL_ERROR_START;
-          SERIAL_ERRORPGM(MSG_ERR_NO_LINENUMBER_WITH_CHECKSUM);
-          SERIAL_ERRORLN(gcode_LastN);
-          serial_count = 0;
+          gcode_line_error(PSTR(MSG_ERR_NO_LINENUMBER_WITH_CHECKSUM), false);
           return;
         }
       }