attempt to reduce space usage

- remove unecessary code
- ifdef "extra" code
- pass data through globals instead of functions accessing static data
- functions non-reentrant, locate tmps in xdata

src/utils.h

@@ -11,7 +11,13 @@
 
 void _delay_ms(uint8_t ms);
 
+#define ACCURATE_DELAY_US
+#ifdef ACCURATE_DELAY_US
 void _delay_us(uint8_t us);
+#else
+#define _delay_us(x) _delay_ms(1)
+#endif
+
 
 char* u32str(uint32_t x, char* buf, uint8_t base);