Squashed 'third_party/apriltag/' content from commit 3e8e974d0

git-subtree-dir: third_party/apriltag
git-subtree-split: 3e8e974d0d8d6ab318abf56d87506d15d7f2cc35
Signed-off-by: Austin Schuh <austin.linux@gmail.com>
Change-Id: I04ba3cb2106b6813a1013d57aa8074c26f856598
diff --git a/common/debug_print.h b/common/debug_print.h
new file mode 100644
index 0000000..77e0d78
--- /dev/null
+++ b/common/debug_print.h
@@ -0,0 +1,41 @@
+/* Copyright (C) 2013-2016, The Regents of The University of Michigan.
+All rights reserved.
+This software was developed in the APRIL Robotics Lab under the
+direction of Edwin Olson, ebolson@umich.edu. This software may be
+available under alternative licensing terms; contact the address above.
+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.
+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.
+The views and conclusions contained in the software and documentation are those
+of the authors and should not be interpreted as representing official policies,
+either expressed or implied, of the Regents of The University of Michigan.
+*/
+#pragma once
+
+#if !defined(NDEBUG) || defined(_DEBUG)
+
+#include <string.h>
+#include <stdio.h>
+#define DEBUG 1
+
+#else
+#define DEBUG 0
+#endif
+
+#define debug_print(fmt, ...) \
+        do { if (DEBUG) fprintf(stderr, "%s:%d:%s(): " fmt, strrchr("/"__FILE__,'/')+1, \
+                                __LINE__, __func__, ##__VA_ARGS__); fflush(stderr);} while (0)