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Annotation of 43BSDReno/lib/libc/hp300/sys/Ovfork.s, revision 1.1.1.1

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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