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bertos/mware/except.h

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+/**
+ * \file
+ * <!--
+ * This file is part of BeRTOS.
+ *
+ * Bertos is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * As a special exception, you may use this file as part of a free software
+ * library without restriction.  Specifically, if other files instantiate
+ * templates or use macros or inline functions from this file, or you compile
+ * this file and link it with other files to produce an executable, this
+ * file does not by itself cause the resulting executable to be covered by
+ * the GNU General Public License.  This exception does not however
+ * invalidate any other reasons why the executable file might be covered by
+ * the GNU General Public License.
+ *
+ * Copyright 2006 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999 Bernie Innocenti <bernie@codewiz.org>
+ *
+ * -->
+ *
+ * \brief C++-like structured exception handling for C programs
+ *
+ * \author Bernie Innocenti <bernie@codewiz.org>
+ */
+#ifndef MWARE_EXCEPT_H
+#define MWARE_EXCEPT_H
+
+#include <cfg/debug.h>
+
+#include <setjmp.h>
+
+#define EXCEPT_CONTEXTS 8
+
+/**
+ * A stack of jump buffers used to record try sites
+ * so they can be reached from throw sites.
+ *
+ * The stack contains return points for each nested
+ * context. jmp_buf's are pushed into the stack at
+ * try points and popped out when the try block ends
+ * normally or when an exception is thrown.
+ */
+extern jmp_buf except_stack[EXCEPT_CONTEXTS];
+extern int except_top;
+
+#define PUSH_EXCEPT	(ASSERT(except_top < EXCEPT_CONTEXTS), setjmp(except_stack[except_top++]))
+#define POP_EXCEPT	(ASSERT(except_top > 0), --except_top)
+#define DO_EXCEPT	(ASSERT(except_top > 0), longjmp(except_stack[--except_top], true))
+
+/**
+ * Jump buffer to use when throwing an exception or aborting an operation
+ *
+ * User code can throw exceptions like this:
+ *
+ * \code
+ *   void a_function_throwing_exceptions(void)
+ *   {
+ *       if (some_error_condition)
+ *          THROW;
+ *   }
+ * \endcode
+ *
+ * Catching exceptions (brackets are optional):
+ *
+ * \code
+ *    EXCEPT_DEFINE;
+ *
+ *    void a_function_catching_an_exception(void)
+ *    {
+ *        TRY
+ *        {
+ *            printf("Entered try block\n");
+ *            a_function_throwing_exceptions();
+ *            printf("Survived execution of critical code\n");
+ *        }
+ *        CATCH
+ *        {
+ *            printf("Exception caught!\n");
+ *        }
+ *        CATCH_END
+ *    }
+ * \endcode
+ *
+ * Simple syntax when you don't need to do anything when catching an excaption:
+ *
+ * \code
+ *    TRY
+ *        printf("Entered try block\n");
+ *        a_function_throwing_exceptions();
+ *        printf("Survived execution of critical code\n");
+ *    TRY_END
+ * \endcode
+ *
+ * You also need to declare the exception stack once in
+ * your global declarations:
+ * \code
+ *    EXCEPT_DEFINE;
+ * \endcode
+ */
+#define TRY          if (PUSH_EXCEPT) { {
+#define TRY_END      } POP_EXCEPT; }
+#define CATCH        } POP_EXCEPT; } else {
+#define CATCH_END    }
+#define THROW        DO_EXCEPT
+
+
+#define EXCEPT_DEFINE \
+	jmp_buf except_stack[EXCEPT_CONTEXTS]; \
+	int except_top;
+
+#endif /* MWARE_EXCEPT_H */