SETJMP(3spp)        RISC/os Reference Manual         SETJMP(3spp)



NAME
     setjmp, longjmp - non-local goto

SYNOPSIS
     #include <saio/setjmp.h>

     void setjmp(env)
     jmpbuf env;

     void longjmp(env, val)
     jmpbuf env;
     int val;

DESCRIPTION
     These routines are useful for dealing with errors and inter-
     rupts encountered in a low-level subroutine of a program.

     Setjmp saves its stack environment in env for later use by
     longjmp. It returns value 0.

     Longjmp restores the environment saved by the last call of
     setjmp.  It then returns in such a way that execution con-
     tinues as if the call of setjmp had just returned the value
     val to the function that invoked setjmp, which must not
     itself have returned in the interim.  If longjmp is called
     from a fault handler, see nofault (3spp), the flow of con-
     trol can be altered in a manner not visible to the compiler
     system.  In this case, all global and static variables that
     can be updated between the setjmp and the longjmp, where
     these updates must be visible after longjmp, should be
     declared "volatile".  If longjmp is not invoked from a fault
     handler, this restriction is not necessary.

SEE ALSO
     nofault(3spp)




















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