Bye bye Wii Motion Plus, hello MPU6050. Also, increase control loop

to 200Hz, add SD card logging, and a number of other changes.

log.c

@@ -0,0 +1,110 @@
+/* log.c */
+
+#include "types.h"
+#include "sdcard.h"
+#include "uart.h"
+#include "timer.h"
+#include "log.h"
+
+/* This is shared with sdcard.c */
+bool log_enabled;
+
+char log_buffer[LOG_BUFFERSIZE];
+unsigned int log_bufferstart;
+unsigned int log_bufferend;
+
+unsigned int log_generation;
+
+/* DO NOT call when the buffer is empty */
+/* This should be safe against writes to the buffer, as the writes only
+ * affect log_bufferend. So no blocking of interrupts is necessary.
+ */
+char log_get_byte(void)
+{
+	char i;
+	i = log_buffer[log_bufferstart++];
+	log_bufferstart = log_bufferstart % LOG_BUFFERSIZE;
+
+	return i;
+}
+
+void log_put_byte(char c)
+{
+	if (!log_enabled)
+		return;
+
+	/* If the buffer is full, we just discard data.
+	 * Better than overrunning.
+	 */
+	if (((log_bufferend + 1) % LOG_BUFFERSIZE) == log_bufferstart)
+		return;
+	log_buffer[log_bufferend++] = c;
+	log_bufferend = log_bufferend % LOG_BUFFERSIZE;
+#if 0
+	putint(c);
+	putch(' ');
+#endif
+}
+
+void log_put_uint16(unsigned int i)
+{
+	log_put_byte(i & 0xff);
+	log_put_byte((i >> 8) & 0xff);
+}
+
+void log_put_uint(unsigned int i)
+{
+	log_put_byte(i & 0xff);
+	log_put_byte((i >> 8) & 0xff);
+	log_put_byte((i >> 16) & 0xff);
+	log_put_byte((i >> 24) & 0xff);
+}
+
+void log_put_header(unsigned int timestamp)
+{
+	log_put_uint(LOG_MAGIC);
+	log_put_uint(log_generation);
+	log_put_uint(timestamp);
+	log_put_uint(log_read_busytime());
+}
+
+void log_put_array(char *data, int length)
+{
+	int i;
+
+	for (i = 0; i < length; i++)
+		log_put_byte(data[i]);
+}
+
+void log_put_float(float f)
+{
+	union {
+		float f;
+		unsigned int i;
+	} data;
+	data.f = f;
+	log_put_uint(data.i);
+}
+
+unsigned int log_busystamp;
+unsigned int log_busytime;
+
+void log_mark_busy(void)
+{
+	unsigned int time = timer_read();
+	log_busystamp = time;
+}
+
+void log_mark_idle(void)
+{
+	unsigned int time = timer_read();
+	unsigned int diff = time - log_busystamp;
+	log_busytime += diff;
+}
+
+unsigned int log_read_busytime(void)
+{
+	unsigned int time = log_busytime;
+	log_busytime = 0;
+	return time;
+}