i386/sys/getpid.s

   1 /*
   2  * Copyright (c) 1999-2003 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved
  27  */
  28 #include "SYS.h"
  29
  30         .data
  31         .private_extern __current_pid
  32 __current_pid:
  33         .long 0
  34 L__current_pid_addr = __current_pid
  35
  36 #if defined(__DYNAMIC__)
  37 #define GET_CURRENT_PID                         \
  38         call    0f                              ; \
  39 0:                                              ; \
  40         popl    %ecx                            ; \
  41         leal    L__current_pid_addr-0b(%ecx), %ecx
  42
  43 #define __current_pid (%ecx)
  44
  45 #else
  46 #define GET_CURRENT_PID
  47 #endif
  48
  49 /*
  50  * If __current_pid is > 0, return it, else make syscall.
  51  * If __current_pid is 0, cache result of syscall.
  52  */
  53 TEXT
  54 LEAF(_getpid, 0)
  55         GET_CURRENT_PID
  56         movl            __current_pid, %eax
  57         testl           %eax, %eax
  58         jle             1f
  59         ret
  60 1:
  61         UNIX_SYSCALL_NONAME(getpid, 0)
  62         movl            %eax, %edx
  63         xorl            %eax, %eax
  64         lock
  65         cmpxchgl        %edx, __current_pid
  66         movl            %edx, %eax
  67         ret