Structured exceptions support for C programs.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@806 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/mware/except.h b/mware/except.h
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+/**
+ * \file
+ * <!--
+ * Copyright 2006 Develer S.r.l. (http://www.develer.com/)
+ * Copyright 1999 Bernardo Innocenti <bernie@develer.com>
+ * This file is part of DevLib - See README.devlib for information.
+ * -->
+ *
+ * \brief C++-like structured exception handling for C programs
+ *
+ * \version $Id$
+ * \author Bernardo Innocenti <bernie@develer.com>
+ */
+#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;
+
+#ifdef _DEBUG
+#      define PUSH_ABORT       ASSERT(abort_top < ABORT_CONTEXTS), setjmp(abort_stack[abort_top++]))
+#      define POP_ABORT        (ASSERT(abort_top > 0), --abort_top)
+#      define DO_ABORT         (ASSERT(abort_top > 0), longjmp(abort_stack[--abort_top], true))
+#else
+#      define PUSH_ABORT       (setjmp(abort_stack[abort_top++]))
+#      define POP_ABORT        (--abort_top)
+#      define DO_ABORT         (longjmp(abort_stack[--abort_top], true))
+#endif
+
+/**
+ * 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_ABORT) { {
+#define TRY_END      } POP_ABORT; }
+#define CATCH        } POP_ABORT; } else {
+#define CATCH_END    }
+#define THROW        DO_ABORT
+
+
+#define EXCEPT_DEFINE \
+       jmp_buf abort_stack[ABORT_CONTEXTS]; \
+       int abort_top;
+
+#endif /* MWARE_EXCEPT_H */