V6/usr/source/s4/execv.s

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/ C library -- execv

/ execv(file, argv);
/
/ where argv is a vector argv[0] ... argv[x], 0
/ last vector element must be 0
/
/ The _exectrap flags is used by the debugger and causes
/ a trace trap on the first instruction of the executed instruction
/ to give a chance to set breakpoints.

.globl	_execv, cerror
.comm	__exectrap,2
rtt	= 6

_execv:
	mov	r5,-(sp)
	mov	sp,r5
	mov	4(r5),0f
	mov	6(r5),0f+2
	tst	__exectrap
	beq	1f
	mov	$170020,-(sp)	/ t-bit
	mov	$1f,-(sp)
	rtt
1:
	sys	0; 9f
	jmp	cerror
.data
9:
	sys	exec; 0:..; ..