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+/* Copyright (C) 1996 Free Software Foundation, Inc.
+   Contributed by Richard Henderson (rth@tamu.edu)
+
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If
+   not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+   Cambridge, MA 02139, USA.  */
+
+/* Bytewise compare two null-terminated strings of length no longer than N.  */
+
+#include <sysdep.h>
+
+	.set noat
+	.set noreorder
+
+	.text
+
+ENTRY(strncmp)
+#ifdef PROF
+	ldgp	gp, 0(pv)
+	lda	AT, _mcount
+	jsr	AT, (AT), _mcount
+	.prologue 1
+#else
+	.prologue 0
+#endif
+
+	xor	a0, a1, t2	# e0    : are s1 and s2 co-aligned?
+	beq	a2, $zerolength	# .. e1 :
+	ldq_u	t0, 0(a0)	# e0    : give cache time to catch up
+	ldq_u	t1, 0(a1)	# .. e1 :
+	and	t2, 7, t2	# e0    :
+	and	a0, 7, t4	# .. e1 : find s1 misalignment
+	lda	t3, -1		# e0    :
+	addq	a2, t4, a2	# .. e1 : bias count by s1 misalignment
+	and	a2, 7, t10	# e1    : ofs of last byte in last word
+	srl	a2, 3, a2	# .. e0 : remaining full words in count
+	and	a1, 7, t5	# e0    : find s2 misalignment
+	bne	t2, $unaligned	# .. e1 :
+
+	/* On entry to this basic block:
+	   t0 == the first word of s1.
+	   t1 == the first word of s2.
+	   t3 == -1.  */
+
+$aligned:
+	mskqh	t3, a1, t3	# e0    : mask off leading garbage
+	nop			# .. e1 :
+	ornot	t1, t3, t1	# e0    :
+	ornot	t0, t3, t0	# .. e1 :
+	cmpbge	zero, t1, t7	# e0    : bits set iff null found
+	beq	a2, $eoc	# .. e1 : check end of count
+	unop			#       :
+	bne	t7, $eos	# e1    :
+
+	/* Aligned compare main loop.
+	   On entry to this basic block:
+	   t0 == an s1 word.
+	   t1 == an s2 word not containing a null.  */
+
+$a_loop:
+	xor	t0, t1, t2	# e0	:
+	bne	t2, $wordcmp	# .. e1 (zdb)
+	ldq_u	t1, 0(a1)	# e0    :
+	ldq_u	t0, 0(a0)	# .. e1 :
+	addq	a1, 8, a1	# e0    :
+	addq	a0, 8, a0	# .. e1 :
+	cmpbge	zero, t1, t7	# e0    :
+	beq	a2, $eoc	# .. e1 :
+	subq	a2, 1, a2	# e0    :
+	beq	t7, $a_loop	# .. e1 :
+	br	$eos		# e1    :
+
+	/* The two strings are not co-aligned.  Align s1 and cope.  */
+$unaligned:
+	subq	a1, t4, a1	# e0	 :
+	unop			#        :
+
+	/* If s2 misalignment is larger than s2 misalignment, we need
+	   extra startup checks to avoid SEGV.  */
+
+	cmplt	t4, t5, t8	# .. e1 :
+	beq	t8, $u_head	# e1    :
+
+	mskqh	t3, t5, t3	# e0    :
+	ornot	t1, t3, t3	# e0    :
+	cmpbge	zero, t3, t7	# e1    : is there a zero?
+	beq	t7, $u_head	# e1    :
+
+	/* We've found a zero in the first partial word of s2.  Align
+	   our current s1 and s2 words and compare what we've got.  */
+
+	extql	t1, t5, t1	# e0    :
+	lda	t3, -1		# .. e1 :
+	insql	t1, a0, t1	# e0    :
+	mskqh	t3, a0, t3	# e0    :
+	ornot	t1, t3, t1	# e0    :
+	ornot	t0, t3, t0	# .. e1 :
+	cmpbge	zero, t1, t7	# e0    : find that zero again
+	beq	a2, $eoc	# .. e1 : and finish up
+	br	$eos		# e1    :
+
+	.align 3
+$u_head:
+	/* We know just enough now to be able to assemble the first
+	   full word of s2.  We can still find a zero at the end of it.
+
+	   On entry to this basic block:
+	   t0 == first word of s1
+	   t1 == first partial word of s2.  */
+
+	ldq_u	t2, 8(a1)	# e0    : load second partial s2 word
+	lda	t3, -1		# .. e1 : create leading garbage mask
+	extql	t1, a1, t1	# e0    : create first s2 word
+	mskqh	t3, a0, t3	# e0    :
+	extqh	t2, a1, t4	# e0    :
+	ornot	t0, t3, t0	# .. e1 : kill s1 garbage
+	or	t1, t4, t1	# e0    : s2 word now complete
+	ornot	t1, t3, t1	# e1    : kill s2 garbage
+	cmpbge	zero, t0, t7	# e0    : find zero in first s1 word
+	beq	a2, $eoc	# .. e1 :
+	lda	t3, -1		# e0    :
+	bne	t7, $eos	# .. e1 :
+	subq	a2, 1, a2	# e0    :
+	xor	t0, t1, t4	# .. e1 : compare aligned words
+	mskql	t3, a1, t3	# e0    : mask out s2[1] bits we have seen
+	bne	t4, $wordcmp	# .. e1 :
+	or	t2, t3, t3	# e0    :
+	cmpbge	zero, t3, t7	# e1    : find zero in high bits of s2[1]
+	bne	t7, $u_final	# e1    :
+
+	/* Unaligned copy main loop.  In order to avoid reading too much,
+	   the loop is structured to detect zeros in aligned words from s2.
+	   This has, unfortunately, effectively pulled half of a loop
+	   iteration out into the head and half into the tail, but it does
+	   prevent nastiness from accumulating in the very thing we want
+	   to run as fast as possible.
+
+	   On entry to this basic block:
+	   t2 == the unshifted low-bits from the next s2 word.  */
+
+	.align 3
+$u_loop:
+	extql	t2, a1, t3	# e0    :
+	ldq_u	t2, 16(a1)	# .. e1 : load next s2 high bits
+	ldq_u	t0, 8(a0)	# e0    : load next s1 word
+	addq	a1, 8, a1	# .. e1 :
+	addq	a0, 8, a0	# e0    :
+	nop			# .. e1 :
+	extqh	t2, a1, t1	# e0    :
+	cmpbge	zero, t0, t7	# .. e1 : find zero in current s1 word
+	or	t1, t3, t1	# e0    :
+	beq	a2, $eoc	# .. e1 : check for end of count
+	subq	a2, 1, a2	# e0    :
+	bne	t7, $eos	# .. e1 :
+	xor	t0, t1, t4	# e0    : compare the words
+	bne	t4, $wordcmp	# .. e1 (zdb)
+	cmpbge	zero, t2, t4	# e0    : find zero in next low bits
+	beq	t4, $u_loop	# .. e1 (zdb)
+
+	/* We've found a zero in the low bits of the last s2 word.  Get
+	   the next s1 word and align them.  */
+$u_final:
+	ldq_u	t0, 8(a0)	# e1    :
+	extql	t2, a1, t1	# .. e0 :
+	cmpbge	zero, t1, t7	# e0    :
+	bne	a2, $eos	# .. e1 :
+
+	/* We've hit end of count.  Zero everything after the count
+	   and compare whats left.  */
+
+	.align 3
+$eoc:
+	mskql	t0, t10, t0
+	mskql	t1, t10, t1
+
+	/* We've found a zero somewhere in a word we just read.
+	   On entry to this basic block:
+	   t0 == s1 word
+	   t1 == s2 word
+	   t7 == cmpbge mask containing the zero.  */
+
+$eos:
+	negq	t7, t6		# e0    : create bytemask of valid data
+	and	t6, t7, t8	# e1    :
+	subq	t8, 1, t6	# e0    :
+	or	t6, t8, t7	# e1    :
+	zapnot	t0, t7, t0	# e0    : kill the garbage
+	zapnot	t1, t7, t1	# .. e1 :
+	xor	t0, t1, v0	# e0    : and compare
+	beq	v0, $done	# .. e1 :
+
+	/* Here we have two differing co-aligned words in t0 & t1.
+           Bytewise compare them and return (t0 > t1 ? 1 : -1).  */
+$wordcmp:
+	cmpbge	t0, t1, t2	# e0    : comparison yields bit mask of ge
+	cmpbge	t1, t0, t3	# .. e1 :
+	xor	t2, t3, t0	# e0    : bits set iff t0/t1 bytes differ
+	negq	t0, t1		# e1    : clear all but least bit
+	and	t0, t1, t0	# e0    :
+	lda	v0, -1		# .. e1 :
+	and	t0, t2, t1	# e0    : was bit set in t0 > t1?
+	cmovne	t1, 1, v0	# .. e1 (zdb)
+
+$done:
+	ret			# e1    :
+
+$zerolength:
+	clr	v0
+	ret
+
+	END(strncmp)