bcopy.s: defines bcopy() and cpyn().

[chris at umcp-cs.UUCP]

# Block copy routines for VAXen.
#	For non-vax people:
#	bcopy (from, to, count) register char *from, *to; register int count; {
#		while (--count >= 0) *to++ = *from++;
#	}
#	cpyn (to, from, count) register char *to, *from; register int count; {
#		while (--count >= 0) *to++ = *from++;
#	}
#
# bcopy (from, to, count) char *from, *to; int count;
#
# Copy "count" bytes from "from" to "to"; not guaranteed to
# work if "from" and "to" overlap.
#
# cpyn (to, from, count) char *to, *from; int count;

	.align	2
	.globl	_cpyn
_cpyn:
	.word	0
	movl	4(ap),r3		# r3 = to
	movl	8(ap),r1		# r1 = from
	brb	2f

	.align	2
	.globl	_bcopy
_bcopy:
	.word	0
	movl	4(ap),r1		# r1 = from
	movl	8(ap),r3		# r3 = to
	brb	2f
1:
	subl2	r0,12(ap)		# count-=65535 (bytes moved this time)
	movc3	r0,(r1),(r3)		# r1, r3 magically point to next 65K
2:
	movzwl	$65535,r0
	cmpl	12(ap),r0		# <= 65535 bytes to move?
	jgtr	1b			# brif not, move 65535 and try again
	movc3	12(ap),(r1),(r3)	# move up to 65535 bytes
	ret
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris at umcp-cs		ARPA:	chris.umcp-cs at UDel-Relay