Add assert macros to aid in debugging.

Adds libopencm3/cm3/assert.h header that provides assertion check macros
similar to those provided by the standard C library.

Thanks to Nicolas Schodet for help.

lib/cm3/assert.c

@@ -0,0 +1,34 @@
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2012 Tomaz Solc <tomaz.solc@tablix.org>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <libopencm3/cm3/assert.h>
+
+void __attribute__((weak)) cm3_assert_failed(void)
+{
+	while(1);
+}
+
+void __attribute__((weak)) cm3_assert_failed_verbose(
+		const char *file __attribute__((unused)),
+		int line __attribute__((unused)),
+		const char *func __attribute__((unused)),
+		const char *assert_expr __attribute__((unused)))
+{
+	cm3_assert_failed();
+}