National Instruments 320685D-01 Locking Process Segments into Memory Using plock(), UNIX Asynchronous Signal Handling

Chapter 5 UNIX Compiler/Linker Issues

National Instruments Corporation 5-7 LabWindows/CVI Programmer Reference Manual

You cannot use the non-ANSI C Sun compil er cc because it does not reco gnize some ANSIC

constructs in the header files, such as function prototypes and the keyw ords const, void, and

volatile.

Locking Process Segments into Memory Using plock()

You can use the UNIX function plock to lock the text and data segments of your program

into memory. However, this function locks all segments of the LabWindows/CVI process, not

just the segments associated with your program. Also, because the text segments of

LabWindows/CVI programs actually reside in the data segment of the LabWindows/CVI

process, you must lock both text and data segments, using plock(PROCLOCK), in order to

lock all text into memory.

Note Your LabWindows/CVI process must have superuser privileges to use the

plock

function.

UNIX Asynchronous Signal Handling

The following signals have special meaning in LabWindows/CVI:

•SIGPOLL (SIGIO) and SIGPIPE—The LabWindows/CVI TCP Library installs

signal handlers for SIGPOLL (SIGIO) and SIGPIPE. If you use the TCP Library and you

want to install handlers for these signals, you must call the LabWindows/CVI handlers

when your handlers are called. If you attempt to set the signal handler to SIG_DFL for

these signals while running in the LabWindows/CVI environment, LabWindows/CVI

restores its own handlers.

•SIGINT and SIGQUIT—Normally, the operating system generates these two signals

when you type certain keystrokes (<Ctrl-C> and <Ctrl-\>) in the window from which

you invoke LabWindows/CVI. If one of these signals occurs while your program is

running and you have not installed a handler for it, LabWindows/CVI suspends

your program the next time it calls a function that processes events (such as

ProcessSystemEvents). If your program does not call any event-processing

functions, it continues to run.

•SIGTERM—LabWindows/CVI treats SIGTERM as a stronger version of SIGINT and

SIGQUIT. If this signal occurs while your program is running and you h av e not i nstall ed

a handler for it, LabWindows/CVI terminates the program, gives you a chance to save

your files, and exits. If SIGTERM occurs when no program is running, LabWindows/CVI

exits immediately.

•SIGBUS, SIGFPE, SIGILL, and SIGSEGV—These signals exist to allow for

hardware exceptions. Because execution cannot continue beyond the instruction that

caused the exception, LabWindows/CVI always catches these signals. If this signal

occurs while your program is running, LabWindows/CVI reports a fatal run-time error