/* Optimized version of the standard memcmp() function.

   This file is part of the GNU C Library.

   Copyright (C) 2000-2018 Free Software Foundation, Inc.

   Contributed by Dan Pop <Dan.Pop@cern.ch>.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 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

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

/* Return: the result of the comparison

   Inputs:

        in0:    dest (aka s1)

        in1:    src  (aka s2)

        in2:    byte count

   In this form, it assumes little endian mode.  For big endian mode,

   the two shifts in .l2 must be inverted:

	shl   	tmp1[0] = r[1 + MEMLAT], sh1   // tmp1 = w0 << sh1

	shr.u   tmp2[0] = r[0 + MEMLAT], sh2   // tmp2 = w1 >> sh2

   and all the mux1 instructions should be replaced by plain mov's.  */

#include <sysdep.h>

#undef ret

#define OP_T_THRES 	16

#define OPSIZ 		8

#define MEMLAT		2

#define start		r15

#define saved_pr	r17

#define saved_lc	r18

#define dest		r19

#define src		r20

#define len		r21

#define asrc		r22

#define tmp		r23

#define value1		r24

#define value2		r25

#define sh2		r28

#define	sh1		r29

#define loopcnt		r30

ENTRY(memcmp)

	.prologue

	alloc 	r2 = ar.pfs, 3, 37, 0, 40

	.rotr	r[MEMLAT + 2], q[MEMLAT + 5], tmp1[4], tmp2[4], val[2]

	.rotp	p[MEMLAT + 4 + 1]

	mov	ret0 = r0		// by default return value = 0

	.save pr, saved_pr

	mov	saved_pr = pr		// save the predicate registers

	.save ar.lc, saved_lc

        mov 	saved_lc = ar.lc	// save the loop counter

	.body

	mov 	dest = in0		// dest

	mov 	src = in1		// src

	mov	len = in2		// len

	sub	tmp = r0, in0		// tmp = -dest

	;;

	and	loopcnt = 7, tmp		// loopcnt = -dest % 8

	cmp.ge	p6, p0 = OP_T_THRES, len	// is len <= OP_T_THRES

(p6)	br.cond.spnt	.cmpfew			// compare byte by byte

	;;

	cmp.eq	p6, p0 = loopcnt, r0

(p6)	br.cond.sptk .dest_aligned

	sub	len = len, loopcnt	// len -= -dest % 8

	adds	loopcnt = -1, loopcnt	// --loopcnt

	;;

	mov	ar.lc = loopcnt

.l1:					// copy -dest % 8 bytes

	ld1	value1 = [src], 1	// value = *src++

	ld1	value2 = [dest], 1

	;;

	cmp.ne	p6, p0 = value1, value2

(p6)	br.cond.spnt .done

	br.cloop.dptk .l1

.dest_aligned:

	and	sh1 = 7, src 		// sh1 = src % 8

	and	tmp = -8, len   	// tmp = len & -OPSIZ

	and	asrc = -8, src		// asrc = src & -OPSIZ  -- align src

	shr.u	loopcnt = len, 3	// loopcnt = len / 8

	and	len = 7, len ;;		// len = len % 8

	shl	sh1 = sh1, 3		// sh1 = 8 * (src % 8)

	adds	loopcnt = -1, loopcnt	// --loopcnt

	mov     pr.rot = 1 << 16 ;;	// set rotating predicates

	sub	sh2 = 64, sh1		// sh2 = 64 - sh1

	mov	ar.lc = loopcnt		// set LC

	cmp.eq  p6, p0 = sh1, r0 	// is the src aligned?

(p6)    br.cond.sptk .src_aligned

	add	src = src, tmp		// src += len & -OPSIZ

	mov	ar.ec = MEMLAT + 4 + 1 	// four more passes needed

	ld8	r[1] = [asrc], 8 ;;	// r[1] = w0

	.align	32

// We enter this loop with p6 cleared by the above comparison

.l2:

(p[0])		ld8	r[0] = [asrc], 8		// r[0] = w1

(p[0])		ld8	q[0] = [dest], 8

(p[MEMLAT])	shr.u	tmp1[0] = r[1 + MEMLAT], sh1	// tmp1 = w0 >> sh1

(p[MEMLAT])	shl	tmp2[0] = r[0 + MEMLAT], sh2  	// tmp2 = w1 << sh2

(p[MEMLAT+4])	cmp.ne	p6, p0 = q[MEMLAT + 4], val[1]

(p[MEMLAT+3])	or	val[0] = tmp1[3], tmp2[3] 	// val = tmp1 | tmp2

(p6)		br.cond.spnt .l2exit

		br.ctop.sptk    .l2

		br.cond.sptk .cmpfew

.l3exit:

	mux1	value1 = r[MEMLAT], @rev

	mux1	value2 = q[MEMLAT], @rev

	cmp.ne	p6, p0 = r0, r0	;;	// clear p6

.l2exit:

(p6)	mux1	value1 = val[1], @rev

(p6)	mux1	value2 = q[MEMLAT + 4], @rev ;;

	cmp.ltu	p6, p7 = value2, value1 ;;

(p6)	mov	ret0 = -1

(p7)	mov	ret0 = 1

	mov     pr = saved_pr, -1    	// restore the predicate registers

	mov 	ar.lc = saved_lc	// restore the loop counter

	br.ret.sptk.many b0

.src_aligned:

	cmp.ne	p6, p0 = r0, r0		// clear p6

	mov     ar.ec = MEMLAT + 1 ;;	// set EC

.l3:

(p[0])		ld8	r[0] = [src], 8

(p[0])		ld8	q[0] = [dest], 8

(p[MEMLAT])	cmp.ne	p6, p0 = r[MEMLAT], q[MEMLAT]

(p6)		br.cond.spnt .l3exit

		br.ctop.dptk .l3 ;;

.cmpfew:

	cmp.eq	p6, p0 = len, r0	// is len == 0 ?

	adds	len = -1, len		// --len;

(p6)	br.cond.spnt	.restore_and_exit ;;

	mov	ar.lc = len

.l4:

	ld1	value1 = [src], 1

	ld1	value2 = [dest], 1

	;;

	cmp.ne	p6, p0 = value1, value2

(p6)	br.cond.spnt	.done

	br.cloop.dptk	.l4 ;;

.done:

(p6)	sub	ret0 = value2, value1	// don't execute it if falling thru

.restore_and_exit:

	mov     pr = saved_pr, -1    	// restore the predicate registers

	mov 	ar.lc = saved_lc	// restore the loop counter

	br.ret.sptk.many b0

END(memcmp)

weak_alias (memcmp, bcmp)

libc_hidden_builtin_def (memcmp)