On Mon, Feb 28, 2005 at 11:39:52PM +0800, Kathy Quinlan wrote: > I have this: > > #include <machine/clock.h> > > In program I use this: > > DELAY(1000); > > I get this: > > undefined referance to 'DELAY' > > when I compile the program with GCC with flags -Wall -g -o com main.c > > ANY ideas ?? > > I have looked in the relevent header and it seems to be there
Yes, it is in clock.h, but... /*- * Kernel interface to machine-dependent clock driver. That's the way that clock.h starts. The 'kernel interface' part means that this is a header file that declares functions that are used *only* within the FreeBSD kernel - since they are only implemented in another part of the kernel code. You cannot use these definitions and functions from a userland program, as you are trying to do. The reason that the DELAY() declaration seems to be in the header file, yet the compiler does not see it, is the #ifdef _KERNEL at the top of clock.h :) This is just a level of protection that accomplishes exactly that - no userland program should *ever* define the _KERNEL symbol, so no userland program will be fooled into believing that there is a DELAY() function that it could possibly use. It simply cannot, since the DELAY() function is declared within kernel code for use by the kernel only. If you want a high-precision delay/sleep interface in a userland program, take a look at the usleep(2) and nanosleep(2) syscalls. G'luck, Peter -- Peter Pentchev [EMAIL PROTECTED] [EMAIL PROTECTED] [EMAIL PROTECTED] PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553 I am the meaning of this sentence.
pgp33T3UcsqGT.pgp
Description: PGP signature
