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Annotation of 43BSDReno/lib/libc/hp300/sys/Ovfork.s, revision 1.1

1.1     ! root        1: /*-
        !             2:  * Copyright (c) 1990 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * the Systems Programming Group of the University of Utah Computer
        !             7:  * Science Department.
        !             8:  *
        !             9:  * Redistribution and use in source and binary forms are permitted
        !            10:  * provided that: (1) source distributions retain this entire copyright
        !            11:  * notice and comment, and (2) distributions including binaries display
        !            12:  * the following acknowledgement:  ``This product includes software
        !            13:  * developed by the University of California, Berkeley and its contributors''
        !            14:  * in the documentation or other materials provided with the distribution
        !            15:  * and in all advertising materials mentioning features or use of this
        !            16:  * software. Neither the name of the University nor the names of its
        !            17:  * contributors may be used to endorse or promote products derived
        !            18:  * from this software without specific prior written permission.
        !            19:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            20:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            21:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            22:  */
        !            23: 
        !            24: #if defined(LIBC_SCCS) && !defined(lint)
        !            25:        .asciz "@(#)Ovfork.s    5.1 (Berkeley) 5/12/90"
        !            26: #endif /* LIBC_SCCS and not lint */
        !            27: 
        !            28: /*
        !            29:  * @(#)vfork.s 4.1 (Berkeley) 12/21/80
        !            30:  * C library -- vfork
        !            31:  */
        !            32: 
        !            33: /*
        !            34:  * pid = vfork();
        !            35:  *
        !            36:  * d1 == 0 in parent process, d1 == 1 in child process.
        !            37:  * d0 == pid of child in parent, d0 == pid of parent in child.
        !            38:  *
        !            39:  * trickery here, due to keith sklower, uses ret to clear the stack,
        !            40:  * and then returns with a jump indirect, since only one person can return
        !            41:  * with a ret off this stack... we do the ret before we vfork!
        !            42:  */
        !            43: 
        !            44:        vfork = 66
        !            45: .globl _vfork
        !            46: 
        !            47: _vfork:
        !            48:        movl    sp@+,a0
        !            49:        movl    #vfork,d0
        !            50:        trap    #0
        !            51:        jcc     vforkok
        !            52:        jmp     verror
        !            53: vforkok:
        !            54:        tstl    d1              /* child process ? */
        !            55:        jne     child           /* yes */
        !            56:        jcc     parent          /* if c-bit not set, fork ok */
        !            57:        .globl  _errno
        !            58: verror:
        !            59:        movl    d0,_errno
        !            60:        moveq   #-1,d0
        !            61:        jmp     a0@
        !            62: child:
        !            63:        clrl    d0
        !            64: parent:
        !            65:        jmp     a0@

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