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setjmp(3avr) | avr-libc | setjmp(3avr) |
NAME¶
setjmp - <setjmp.h>: Non-local gotoFunctions¶
int setjmp (jmp_buf __jmpb)
void longjmp (jmp_buf __jmpb, int __ret) __ATTR_NORETURN__
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:
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); } }
Function Documentation¶
void longjmp (jmp_buf __jmpb, int __ret)¶
Non-local jump to a saved stack context.1 #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:
Parameters:
__ret Value to return to the caller of setjmp().
Returns:
int setjmp (jmp_buf __jmpb)¶
Save stack context for non-local goto.1 #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:
Returns:
Author¶
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