Fixed a number of bugs caused by using abs() on floats and long ints. Added support for selectively inverting bits of the stepping port. Debugged, optimized and cleaned up timing code for the step-pulses.

wiring_serial.c

@@ -28,7 +28,7 @@
 // using a ring buffer (I think), in which rx_buffer_head is the index of the
 // location to which to write the next incoming character and rx_buffer_tail
 // is the index of the location from which to read.
-#define RX_BUFFER_SIZE 128
+#define RX_BUFFER_SIZE 256
 
 unsigned char rx_buffer[RX_BUFFER_SIZE];