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Annotation of researchv10dc/libc/sys/vfork.s, revision 1.1

1.1     ! root        1: # C library -- vfork
        !             2: 
        !             3: # pid = vfork();
        !             4: #
        !             5: # r1 == 0 in parent process, r1 == 1 in child process.
        !             6: # r0 == pid of child in parent, r0 == pid of parent in child.
        !             7: #
        !             8: # trickery here, due to keith sklower, uses ret to clear the stack,
        !             9: # and then returns with a jump indirect, since only one person can return
        !            10: # with a ret off this stack... we do the ret before we vfork!
        !            11: # 
        !            12: 
        !            13:        .set    vfork,66
        !            14: .globl _vfork
        !            15: 
        !            16: _vfork:
        !            17:        .word   0x0000
        !            18:        movl    16(fp),r2
        !            19:        movab   here,16(fp)
        !            20:        ret
        !            21: here:
        !            22:        chmk    $vfork
        !            23:        bcc     vforkok
        !            24:        jmp     verror
        !            25: vforkok:
        !            26:        tstl    r1              # child process ?
        !            27:        bneq    child   # yes
        !            28:        bcc     parent          # if c-bit not set, fork ok
        !            29: .globl _errno
        !            30: verror:
        !            31:        movl    r0,_errno
        !            32:        mnegl   $1,r0
        !            33:        jmp     (r2)
        !            34: child:
        !            35:        clrl    r0
        !            36: parent:
        !            37:        jmp     (r2)

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