1/* 2 * Copyright (c) 1983 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 */ 6 7#ifdef SYSLIBC_SCCS 8_sccsid:.asciz "@(#)Ovfork.s 5.1 (Berkeley) 07/02/86" 9#endif SYSLIBC_SCCS 10 11/* 12 * C library -- vfork 13 * pid = vfork(); 14 * 15 * r1 == 0 in parent process, r1 == 1 in child process. 16 * r0 == pid of child in parent, r0 == pid of parent in child. 17 * 18 * trickery here, due to keith sklower, uses ret to clear the stack, 19 * and then returns with a jump indirect, since only one person can return 20 * with a ret off this stack... we do the ret before we vfork! 21 * 22 */ 23 24 .set vfork,66 25.globl _vfork 26 27_vfork: 28 .word 0x0000 29 movl -8(fp),r2 30 movab here,-8(fp) 31 ret 32here: 33 kcall $vfork 34 bcc vforkok 35 jmp verror 36vforkok: 37 tstl r1 # child process ? 38 bneq child # yes 39 jbr parent 40.globl _errno 41verror: 42 movl r0,_errno 43 mnegl $1,r0 44 jmp (r2) 45child: 46 clrl r0 47parent: 48 jmp (r2) 49