Reg putname() function

[SATHISH.J]

Hi,

Can anybody please tell me what the following assembly code means:
Tne function put_unused_fd() does FD_CLR() to clear the file descriptor
allocated in case file pointer could not be got. Before returning -1 as
file descriptor it goes to put_unused_fd() which calls FD_CLR() which is
as follows;

#define __FD_CLR(fd,fdsetp) \
                __asm__ __volatile__("btrl %1,%0": \
                        "=m" (*(__kernel_fd_set *) (fdsetp)):"r" ((int)
(fd)))

This is in asm/posixtypes.h. Please decipher this for me.

Thanks in advance,
Regards,
sathish