Provided by: avr-libc_1.2.3-3_all bug

NAME

       Setjmp and Longjmp -

Detailed Description

       While the C language has the dreaded goto statement, it can only be
       used to jump to a label in the same (local) function. In order to jump
       directly to another (non-local) function, the C library provides the
       setjmp() and longjmp() functions. setjmp() and longjmp() are useful for
       dealing with errors and interrupts encountered in a low-level
       subroutine of a program.

       Note:
           setjmp() and longjmp() make programs hard to understand and
           maintain. If possible, an alternative should be used.

           longjmp() can destroy changes made to global register variables
           (see How to permanently bind a variable to a register?).

       For a very detailed discussion of setjmp()/longjmp(), see Chapter 7 of
       Advanced Programming in the UNIX Environment, by W. Richard Stevens.

       Example:

           #include <setjmp.h>

           jmp_buf env;

           int main (void)
           {
               if (setjmp (env))
               {
                   ... handle error ...
               }

               while (1)
               {
                  ... main processing loop which calls foo() some where ...
               }
           }

           ...

           void foo (void)
           {
               ... blah, blah, blah ...

               if (err)
               {
                   longjmp (env, 1);
               }
           }

   Functions
       int setjmp (jmp_buf __jmpb)
       void longjmp (jmp_buf __jmpb, int __ret) __ATTR_NORETURN__

Function Documentation

   void longjmp (jmp_buf __jmpb, int __ret)
       Non-local jump to a saved stack context.

        #include <setjmp.h>

       longjmp() restores the environment saved by the last call of setjmp()
       with the corresponding __jmpb argument. After longjmp() is completed,
       program execution continues as if the corresponding call of setjmp()
       had just returned the value __ret.

       Note:
           longjmp() cannot cause 0 to be returned. If longjmp() is invoked
           with a second argument of 0, 1 will be returned instead.

       Parameters:
           __jmpb Information saved by a previous call to setjmp().
           __ret Value to return to the caller of setjmp().

       Returns:
           This function never returns.

   int setjmp (jmp_buf __jmpb)
       Save stack context for non-local goto.

        #include <setjmp.h>

       setjmp() saves the stack context/environment in __jmpb for later use by
       longjmp(). The stack context will be invalidated if the function which
       called setjmp() returns.

       Parameters:
           __jmpb Variable of type jmp_buf which holds the stack information
           such that the environment can be restored.

       Returns:
           setjmp() returns 0 if returning directly, and non-zero when
           returning from longjmp() using the saved context.