sdlog2 performance increased, fixes and cleanup

src/modules/sdlog2/logbuffer.c

@@ -0,0 +1,144 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Anton Babushkin <rk3dov@gmail.com>
+ *
+ * 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 logbuffer.c
+ *
+ * Ring FIFO buffer for binary log data.
+ *
+ * @author Anton Babushkin <rk3dov@gmail.com>
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "logbuffer.h"
+
+void logbuffer_init(struct logbuffer_s *lb, int size)
+{
+	lb->size  = size;
+	lb->write_ptr = 0;
+	lb->read_ptr = 0;
+	lb->data = malloc(lb->size);
+}
+
+int logbuffer_free(struct logbuffer_s *lb)
+{
+	int n = lb->read_ptr - lb->write_ptr - 1;
+
+	if (n < 0) {
+		n += lb->size;
+	}
+
+	return n;
+}
+
+int logbuffer_count(struct logbuffer_s *lb)
+{
+	int n = lb->write_ptr - lb->read_ptr;
+
+	if (n < 0) {
+		n += lb->size;
+	}
+
+	return n;
+}
+
+int logbuffer_is_empty(struct logbuffer_s *lb)
+{
+	return lb->read_ptr == lb->write_ptr;
+}
+
+bool logbuffer_write(struct logbuffer_s *lb, void *ptr, int size)
+{
+	// bytes available to write
+	int available = lb->read_ptr - lb->write_ptr - 1;
+
+	if (available < 0)
+		available += lb->size;
+
+	if (size > available) {
+		// buffer overflow
+		return false;
+	}
+
+	char *c = (char *) ptr;
+	int n = lb->size - lb->write_ptr;	// bytes to end of the buffer
+
+	if (n < size) {
+		// message goes over end of the buffer
+		memcpy(&(lb->data[lb->write_ptr]), c, n);
+		lb->write_ptr = 0;
+
+	} else {
+		n = 0;
+	}
+
+	// now: n = bytes already written
+	int p = size - n;	// number of bytes to write
+	memcpy(&(lb->data[lb->write_ptr]), &(c[n]), p);
+	lb->write_ptr = (lb->write_ptr + p) % lb->size;
+	return true;
+}
+
+int logbuffer_get_ptr(struct logbuffer_s *lb, void **ptr, bool *is_part)
+{
+	// bytes available to read
+	int available = lb->write_ptr - lb->read_ptr;
+
+	if (available == 0) {
+		return 0;	// buffer is empty
+	}
+
+	int n = 0;
+
+	if (available > 0) {
+		// read pointer is before write pointer, write all available bytes
+		n = available;
+		*is_part = false;
+
+	} else {
+		// read pointer is after write pointer, write bytes from read_ptr to end
+		n = lb->size - lb->read_ptr;
+		*is_part = true;
+	}
+
+	*ptr = &(lb->data[lb->read_ptr]);
+	return n;
+}
+
+void logbuffer_mark_read(struct logbuffer_s *lb, int n)
+{
+	lb->read_ptr = (lb->read_ptr + n) % lb->size;
+}