Added logging with worker thread for microSD writes, untested, but feature-complete

apps/sdlog/sdlog_ringbuffer.c

@@ -0,0 +1,91 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Lorenz Meier <lm@inf.ethz.ch>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file sdlog_log.c
+ * MAVLink text logging.
+ *
+ * @author Lorenz Meier <lm@inf.ethz.ch>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "sdlog_ringbuffer.h"
+
+void sdlog_logbuffer_init(struct sdlog_logbuffer *lb, int size)
+{
+	lb->size  = size;
+	lb->start = 0;
+	lb->count = 0;
+	lb->elems = (struct sdlog_sysvector *)calloc(lb->size, sizeof(struct sdlog_sysvector));
+}
+
+int sdlog_logbuffer_is_full(struct sdlog_logbuffer *lb)
+{
+	return lb->count == (int)lb->size;
+}
+
+int sdlog_logbuffer_is_empty(struct sdlog_logbuffer *lb)
+{
+	return lb->count == 0;
+}
+
+
+// XXX make these functions thread-safe
+void sdlog_logbuffer_write(struct sdlog_logbuffer *lb, const struct sdlog_sysvector *elem)
+{
+	int end = (lb->start + lb->count) % lb->size;
+	memcpy(&(lb->elems[end]), elem, sizeof(struct sdlog_sysvector));
+
+	if (sdlog_logbuffer_is_full(lb)) {
+		lb->start = (lb->start + 1) % lb->size; /* full, overwrite */
+
+	} else {
+		++lb->count;
+	}
+}
+
+int sdlog_logbuffer_read(struct sdlog_logbuffer *lb, struct sdlog_sysvector *elem)
+{
+	if (!sdlog_logbuffer_is_empty(lb)) {
+		memcpy(elem, &(lb->elems[lb->start]), sizeof(struct sdlog_sysvector));
+		lb->start = (lb->start + 1) % lb->size;
+		--lb->count;
+		return 0;
+
+	} else {
+		return 1;
+	}
+}