G-code parser: check for end of line in the parser.

This raises abstraction and even makes the binary a bit smaller
(2 bytes without SD, 14 bytes with SD).

A G-code file with 16'384 lines of comments, 64 bytes per line
( = 1 MB file size), is read and parsed from SD card in 2:47
minutes, or at a speed of 5924 bytes/second.

gcode_parse.c

@@ -100,9 +100,16 @@ void gcode_init(void) {
 	#endif
 }
 
-/// Character Received - add it to our command
-/// \param c the next character to process
-void gcode_parse_char(uint8_t c) {
+/** Character received - add it to our command.
+
+  \param c The next character to process.
+
+  \return Wether end of line was reached.
+
+  This parser operates character by character, so there's no need for a
+  buffer holding the entire line of G-code.
+*/
+uint8_t gcode_parse_char(uint8_t c) {
 	uint8_t checksum_char = c;
 
 	// uppercase
@@ -401,6 +408,8 @@ void gcode_parse_char(uint8_t c) {
 		if (next_target.option_all_relative || next_target.option_e_relative) {
       next_target.target.axis[E] = 0;
 		}
+
+    return 1;
 	}
 
   #ifdef SD
@@ -417,6 +426,8 @@ void gcode_parse_char(uint8_t c) {
     }
   }
   #endif /* SD */
+
+  return 0;
 }
 
 /***************************************************************************\

gcode_parse.h

@@ -72,7 +72,7 @@ extern GCODE_COMMAND next_target;
 void gcode_init(void);
 
 /// accept the next character and process it
-void gcode_parse_char(uint8_t c);
+uint8_t gcode_parse_char(uint8_t c);
 
 // uses the global variable next_target.N
 void request_resend(void);

mendel.c

@@ -271,14 +271,14 @@ int main (void)
 	{
 		// if queue is full, no point in reading chars- host will just have to wait
     if (queue_full() == 0) {
-      uint8_t c;
+      uint8_t c, line_done;
 
       if (( ! gcode_active || gcode_active & GCODE_SOURCE_SERIAL) &&
           serial_rxchars() != 0) {
         gcode_active = GCODE_SOURCE_SERIAL;
         c = serial_popchar();
-        gcode_parse_char(c);
-        if (c == '\r' || c == '\n')
+        line_done = gcode_parse_char(c);
+        if (line_done)
           gcode_active = 0;
       }
 
@@ -294,8 +294,8 @@ int main (void)
           }
           else {
             gcode_active = GCODE_SOURCE_SD;
-            gcode_parse_char(c);
-            if (c == '\r' || c == '\n')
+            line_done = gcode_parse_char(c);
+            if (line_done)
               gcode_active = 0;
           }
         }