projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 8ccf9623 SL |
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) %G%" | |
| 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 | |
| 32 | here: | |
| 33 | kcall $vfork | |
| 34 | bcc vforkok | |
| 35 | jmp verror | |
| 36 | vforkok: | |
| 37 | tstl r1 # child process ? | |
| 38 | bneq child # yes | |
| 39 | jbr parent | |
| 40 | .globl _errno | |
| 41 | verror: | |
| 42 | movl r0,_errno | |
| 43 | mnegl $1,r0 | |
| 44 | jmp (r2) | |
| 45 | child: | |
| 46 | clrl r0 | |
| 47 | parent: | |
| 48 | jmp (r2) |