usr/klibc/arch/alpha/pipe.c

#include <unistd.h>
#include <sys/syscall.h>

/* pipe() on alpha returns both file descriptors in registers --
   $0 and $20 respectively.  This is unlike any other system call,
   as far as I can tell. */

int pipe(int *fds)
{
	register long sc_0 __asm__("$0");
	register long sc_19 __asm__("$19");
	register long sc_20 __asm__("$20");

	sc_0 = __NR_pipe;
	asm volatile ("callsys":"=r" (sc_0), "=r"(sc_19), "=r"(sc_20)
		      :"0"(sc_0)
		      :_syscall_clobbers);

	if (sc_19) {
		errno = sc_19;
		return -1;
	}

	fds[0] = sc_0;
	fds[1] = sc_20;

	return 0;
}