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/* Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
*/
#define import_spp
#define import_xnames
#define import_knames
#define import_libc
#include <iraf.h>
/* CXWHEN -- Post an exception handler. The exception handler procedure
** is called when an exception occurs, unless the exception has been
** disabled. If a user exception handler has not been posted and an
** exception has not been disabled, a system default exception handler is
** called when the exception occurs.
**
** Currently only four exceptions are recognized (import_xwhen):
**
** X_INT interrupt
** X_ARITH arithmetic exception (e.g. divide by zero)
** X_ACV access violation (e.g. illegal memory reference)
** X_IPC write to IPC with no reader
**
** When an exception occurs the user supplied exception handler is called
** with the following argument list:
**
** handler (&exception, &next_handler)
**
** The first argument is the code for the virtual exception calling the user
** handler (the same handler may be posted for more than one exception).
** The second argument is set by the user handler before exiting, and
** must be either the ZLOCPR entry point address of the next exception
** handler to be called or NULL, indicating that normal execution is to
** resume.
**
** For portability reasons, only the virtual exceptions should be used to
** post exception handlers. For good diagnostic messages when an exception
** occurs it is desirable, however, to have a more precise description of
** the actual host system exception which occurred. This may be obtained
** by a call to C_XGMES.
*/
#define SZ_ERRMSG 64
typedef int (*PFI)(); /* pointer to function returning int */
/* C_XWHEN -- Post an exception handler for an exception, or disable the
** exception (not all exceptions can be disabled).
*/
void
c_xwhen (
int exception, /* code for virtual exception */
PFI new_handler, /* new exception handler */
PFI *old_handler /* old exception handler (output) */
)
{
XINT excode = exception;
XINT epa_new_handler = (XINT)new_handler;
XINT epa_old_handler;
XWHEN (&excode, &epa_new_handler, &epa_old_handler);
*old_handler = (PFI)epa_old_handler;
}
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