sysdeps/unix/bsd/sun/m68k/vfork.S

   1 /* Copyright (C) 1991, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <sysdep.h>
  20
  21 #ifndef SYS_vfork
  22 #define SYS_vfork       66
  23 #endif
  24
  25 /* Clone the calling process, but without copying the whole address space.
  26    The the calling process is suspended until the the new process exits or is
  27    replaced by a call to `execve'.  Return -1 for errors, 0 to the new process,
  28    and the process ID of the new process to the old process.  */
  29 .globl ___vfork
  30 ___vfork:
  31         /* Pop the return PC value into A0.  */
  32         movel sp@+, a0
  33
  34         /* Push the syscall number and trap into the kernel.  */
  35         movel #SYS_vfork, sp@-
  36         trap #0
  37         bcs error               /* Branch forward if it failed.  */
  38
  39         /* It succeeded.  See which fork we're in.  D1 is now 0 for the
  40            parent and 1 for the child.  Decrement it to make it -1 (all
  41            bits set) for the parent, and 0 (no bits set) for the child.
  42            Then AND it with D0, so the parent gets D0&-1==R0, and the child
  43            gets D0&0==0.  */
  44         decl d1
  45         andl d1, d0
  46
  47         /* Jump to the return PC.  */
  48         jmp a0@
  49
  50 error:
  51         movel d0, _errno
  52         moveq #-1, d0
  53         jmp a0@
  54
  55 weak_alias (__vfork, vfork)