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Atari Mega Archive 1
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Atari Mega Archive - Volume 1.iso
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mint
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mntlib44.zoo
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mntlib
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purec
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vfork.s
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1992-06-26
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; From the mintlib.
; Pure C version 21-6-92 bm
;
; vfork for MiNT. Note that the return address must be popped off the stack,
; or else it could be clobbered by the child and the parent would be left
; returning to la-la land. Also note that MiNT guarantees that register a1
; will be preserved across a vfork() system call.
;
.globl vfork
.globl __mint ; MiNT version kept here
.comm L_vfsav,128
.globl errno
.globl tfork ; thread.c
.text
.even
vfork:
move.l (sp)+,a1 ; save return address; this is important!
tst.w __mint
beq L_TOS ; go do the TOS thing
move.w #$113,-(sp) ; push MiNT Pvfork() parameter
trap #1 ; Vfork
addq.l #2,sp
tst.l d0 ; error??
bmi L_err
jmp (a1) ; return
L_TOS:
movem.l d2-d7/a1-a6,L_vfsav ; save registers
move.l #L_vfsav,d0 ; arguments are passed in a0 (func) and d0 (arg)
lea.l L_newprog,a0
jsr tfork ; tfork(L_newprog, L_vfsav)
movem.l L_vfsav,d2-d7/a1-a6 ; restore reggies
tst.l d0 ; fork went OK??
bmi L_err ; no -- error
jmp (a1) ; return to caller
L_err:
neg.l d0
move.w d0,errno ; save error code in errno
moveq.l #-1,d0 ; return -1
jmp (a1) ; return
;
; L_newprog: here is where the child starts executing, with argument
; L_vfsav. We restore registers, zero d0, and jump back to parent
;
L_newprog:
addq.l #4,sp ; pop useless return address
move.l d0,a0 ; get address of save area
movem.l (a0),d2-d7/a1-a6 ; restore reggies
clr.l d0 ; child always returns 0 from vfork
jmp (a1) ; back to caller, as child process