#! /usr/bin/env perl
# Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
#
# Licensed under the OpenSSL license (the "License").  You may not use
# this file except in compliance with the License.  You can obtain a copy
# in the file LICENSE in the source distribution or at
# https://www.openssl.org/source/license.html


# ====================================================================
# Written by Andy Polyakov <appro@openssl.org> for the OpenSSL
# project. The module is, however, dual licensed under OpenSSL and
# CRYPTOGAMS licenses depending on where you obtain it. For further
# details see http://www.openssl.org/~appro/cryptogams/.
# ====================================================================
#
# ECP_NISTZ256 module for ARMv8.
#
# February 2015.
#
# Original ECP_NISTZ256 submission targeting x86_64 is detailed in
# http://eprint.iacr.org/2013/816.
#
#			with/without -DECP_NISTZ256_ASM
# Apple A7		+120-360%
# Cortex-A53		+120-400%
# Cortex-A57		+120-350%
# X-Gene		+200-330%
# Denver		+140-400%
#
# Ranges denote minimum and maximum improvement coefficients depending
# on benchmark. Lower coefficients are for ECDSA sign, server-side
# operation. Keep in mind that +400% means 5x improvement.

$flavour = shift;
while (($output=shift) && ($output!~/\w[\w\-]*\.\w+$/)) {}

$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
( $xlate="${dir}arm-xlate.pl" and -f $xlate ) or
( $xlate="${dir}../../perlasm/arm-xlate.pl" and -f $xlate) or
die "can't locate arm-xlate.pl";

open OUT,"| \"$^X\" $xlate $flavour $output";
*STDOUT=*OUT;

{
my ($rp,$ap,$bp,$bi,$a0,$a1,$a2,$a3,$t0,$t1,$t2,$t3,$poly1,$poly3,
    $acc0,$acc1,$acc2,$acc3,$acc4,$acc5) =
    map("x$_",(0..17,19,20));

my ($acc6,$acc7)=($ap,$bp);	# used in __ecp_nistz256_sqr_mont

$code.=<<___;
#include "arm_arch.h"

.text
___
########################################################################
# Convert ecp_nistz256_table.c to layout expected by ecp_nistz_gather_w7
#
$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
open TABLE,"<ecp_nistz256_table.c"		or
open TABLE,"<${dir}../ecp_nistz256_table.c"	or
die "failed to open ecp_nistz256_table.c:",$!;

use integer;

foreach(<TABLE>) {
	s/TOBN\(\s*(0x[0-9a-f]+),\s*(0x[0-9a-f]+)\s*\)/push @arr,hex($2),hex($1)/geo;
}
close TABLE;

# See ecp_nistz256_table.c for explanation for why it's 64*16*37.
# 64*16*37-1 is because $#arr returns last valid index or @arr, not
# amount of elements.
die "insane number of elements" if ($#arr != 64*16*37-1);

$code.=<<___;
.globl	ecp_nistz256_precomputed
.type	ecp_nistz256_precomputed,%object
.align	12
ecp_nistz256_precomputed:
___
########################################################################
# this conversion smashes P256_POINT_AFFINE by individual bytes with
# 64 byte interval, similar to
#	1111222233334444
#	1234123412341234
for(1..37) {
	@tbl = splice(@arr,0,64*16);
	for($i=0;$i<64;$i++) {
		undef @line;
		for($j=0;$j<64;$j++) {
			push @line,(@tbl[$j*16+$i/4]>>(($i%4)*8))&0xff;
		}
		$code.=".byte\t";
		$code.=join(',',map { sprintf "0x%02x",$_} @line);
		$code.="\n";
	}
}
$code.=<<___;
.size	ecp_nistz256_precomputed,.-ecp_nistz256_precomputed
.align	5
.Lpoly:
.quad	0xffffffffffffffff,0x00000000ffffffff,0x0000000000000000,0xffffffff00000001
.LRR:	// 2^512 mod P precomputed for NIST P256 polynomial
.quad	0x0000000000000003,0xfffffffbffffffff,0xfffffffffffffffe,0x00000004fffffffd
.Lone_mont:
.quad	0x0000000000000001,0xffffffff00000000,0xffffffffffffffff,0x00000000fffffffe
.Lone:
.quad	1,0,0,0
.asciz	"ECP_NISTZ256 for ARMv8, CRYPTOGAMS by <appro\@openssl.org>"

// void	ecp_nistz256_to_mont(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_to_mont
.type	ecp_nistz256_to_mont,%function
.align	6
ecp_nistz256_to_mont:
	stp	x29,x30,[sp,#-32]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]

	ldr	$bi,.LRR		// bp[0]
	ldp	$a0,$a1,[$ap]
	ldp	$a2,$a3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24
	adr	$bp,.LRR		// &bp[0]

	bl	__ecp_nistz256_mul_mont

	ldp	x19,x20,[sp,#16]
	ldp	x29,x30,[sp],#32
	ret
.size	ecp_nistz256_to_mont,.-ecp_nistz256_to_mont

// void	ecp_nistz256_from_mont(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_from_mont
.type	ecp_nistz256_from_mont,%function
.align	4
ecp_nistz256_from_mont:
	stp	x29,x30,[sp,#-32]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]

	mov	$bi,#1			// bp[0]
	ldp	$a0,$a1,[$ap]
	ldp	$a2,$a3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24
	adr	$bp,.Lone		// &bp[0]

	bl	__ecp_nistz256_mul_mont

	ldp	x19,x20,[sp,#16]
	ldp	x29,x30,[sp],#32
	ret
.size	ecp_nistz256_from_mont,.-ecp_nistz256_from_mont

// void	ecp_nistz256_mul_mont(BN_ULONG x0[4],const BN_ULONG x1[4],
//					     const BN_ULONG x2[4]);
.globl	ecp_nistz256_mul_mont
.type	ecp_nistz256_mul_mont,%function
.align	4
ecp_nistz256_mul_mont:
	stp	x29,x30,[sp,#-32]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]

	ldr	$bi,[$bp]		// bp[0]
	ldp	$a0,$a1,[$ap]
	ldp	$a2,$a3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_mul_mont

	ldp	x19,x20,[sp,#16]
	ldp	x29,x30,[sp],#32
	ret
.size	ecp_nistz256_mul_mont,.-ecp_nistz256_mul_mont

// void	ecp_nistz256_sqr_mont(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_sqr_mont
.type	ecp_nistz256_sqr_mont,%function
.align	4
ecp_nistz256_sqr_mont:
	stp	x29,x30,[sp,#-32]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]

	ldp	$a0,$a1,[$ap]
	ldp	$a2,$a3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_sqr_mont

	ldp	x19,x20,[sp,#16]
	ldp	x29,x30,[sp],#32
	ret
.size	ecp_nistz256_sqr_mont,.-ecp_nistz256_sqr_mont

// void	ecp_nistz256_add(BN_ULONG x0[4],const BN_ULONG x1[4],
//					const BN_ULONG x2[4]);
.globl	ecp_nistz256_add
.type	ecp_nistz256_add,%function
.align	4
ecp_nistz256_add:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	ldp	$acc0,$acc1,[$ap]
	ldp	$t0,$t1,[$bp]
	ldp	$acc2,$acc3,[$ap,#16]
	ldp	$t2,$t3,[$bp,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_add

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_add,.-ecp_nistz256_add

// void	ecp_nistz256_div_by_2(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_div_by_2
.type	ecp_nistz256_div_by_2,%function
.align	4
ecp_nistz256_div_by_2:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	ldp	$acc0,$acc1,[$ap]
	ldp	$acc2,$acc3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_div_by_2

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_div_by_2,.-ecp_nistz256_div_by_2

// void	ecp_nistz256_mul_by_2(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_mul_by_2
.type	ecp_nistz256_mul_by_2,%function
.align	4
ecp_nistz256_mul_by_2:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	ldp	$acc0,$acc1,[$ap]
	ldp	$acc2,$acc3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24
	mov	$t0,$acc0
	mov	$t1,$acc1
	mov	$t2,$acc2
	mov	$t3,$acc3

	bl	__ecp_nistz256_add	// ret = a+a	// 2*a

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_mul_by_2,.-ecp_nistz256_mul_by_2

// void	ecp_nistz256_mul_by_3(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_mul_by_3
.type	ecp_nistz256_mul_by_3,%function
.align	4
ecp_nistz256_mul_by_3:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	ldp	$acc0,$acc1,[$ap]
	ldp	$acc2,$acc3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24
	mov	$t0,$acc0
	mov	$t1,$acc1
	mov	$t2,$acc2
	mov	$t3,$acc3
	mov	$a0,$acc0
	mov	$a1,$acc1
	mov	$a2,$acc2
	mov	$a3,$acc3

	bl	__ecp_nistz256_add	// ret = a+a	// 2*a

	mov	$t0,$a0
	mov	$t1,$a1
	mov	$t2,$a2
	mov	$t3,$a3

	bl	__ecp_nistz256_add	// ret += a	// 2*a+a=3*a

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_mul_by_3,.-ecp_nistz256_mul_by_3

// void	ecp_nistz256_sub(BN_ULONG x0[4],const BN_ULONG x1[4],
//				        const BN_ULONG x2[4]);
.globl	ecp_nistz256_sub
.type	ecp_nistz256_sub,%function
.align	4
ecp_nistz256_sub:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	ldp	$acc0,$acc1,[$ap]
	ldp	$acc2,$acc3,[$ap,#16]
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_sub_from

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_sub,.-ecp_nistz256_sub

// void	ecp_nistz256_neg(BN_ULONG x0[4],const BN_ULONG x1[4]);
.globl	ecp_nistz256_neg
.type	ecp_nistz256_neg,%function
.align	4
ecp_nistz256_neg:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	mov	$bp,$ap
	mov	$acc0,xzr		// a = 0
	mov	$acc1,xzr
	mov	$acc2,xzr
	mov	$acc3,xzr
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	bl	__ecp_nistz256_sub_from

	ldp	x29,x30,[sp],#16
	ret
.size	ecp_nistz256_neg,.-ecp_nistz256_neg

// note that __ecp_nistz256_mul_mont expects a[0-3] input pre-loaded
// to $a0-$a3 and b[0] - to $bi
.type	__ecp_nistz256_mul_mont,%function
.align	4
__ecp_nistz256_mul_mont:
	mul	$acc0,$a0,$bi		// a[0]*b[0]
	umulh	$t0,$a0,$bi

	mul	$acc1,$a1,$bi		// a[1]*b[0]
	umulh	$t1,$a1,$bi

	mul	$acc2,$a2,$bi		// a[2]*b[0]
	umulh	$t2,$a2,$bi

	mul	$acc3,$a3,$bi		// a[3]*b[0]
	umulh	$t3,$a3,$bi
	ldr	$bi,[$bp,#8]		// b[1]

	adds	$acc1,$acc1,$t0		// accumulate high parts of multiplication
	 lsl	$t0,$acc0,#32
	adcs	$acc2,$acc2,$t1
	 lsr	$t1,$acc0,#32
	adcs	$acc3,$acc3,$t2
	adc	$acc4,xzr,$t3
	mov	$acc5,xzr
___
for($i=1;$i<4;$i++) {
        # Reduction iteration is normally performed by accumulating
        # result of multiplication of modulus by "magic" digit [and
        # omitting least significant word, which is guaranteed to
        # be 0], but thanks to special form of modulus and "magic"
        # digit being equal to least significant word, it can be
        # performed with additions and subtractions alone. Indeed:
        #
        #            ffff0001.00000000.0000ffff.ffffffff
        # *                                     abcdefgh
        # + xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx.abcdefgh
        #
        # Now observing that ff..ff*x = (2^n-1)*x = 2^n*x-x, we
        # rewrite above as:
        #
        #   xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx.abcdefgh
        # + abcdefgh.abcdefgh.0000abcd.efgh0000.00000000
        # - 0000abcd.efgh0000.00000000.00000000.abcdefgh
        #
        # or marking redundant operations:
        #
        #   xxxxxxxx.xxxxxxxx.xxxxxxxx.xxxxxxxx.--------
        # + abcdefgh.abcdefgh.0000abcd.efgh0000.--------
        # - 0000abcd.efgh0000.--------.--------.--------

$code.=<<___;
	subs	$t2,$acc0,$t0		// "*0xffff0001"
	sbc	$t3,$acc0,$t1
	adds	$acc0,$acc1,$t0		// +=acc[0]<<96 and omit acc[0]
	 mul	$t0,$a0,$bi		// lo(a[0]*b[i])
	adcs	$acc1,$acc2,$t1
	 mul	$t1,$a1,$bi		// lo(a[1]*b[i])
	adcs	$acc2,$acc3,$t2		// +=acc[0]*0xffff0001
	 mul	$t2,$a2,$bi		// lo(a[2]*b[i])
	adcs	$acc3,$acc4,$t3
	 mul	$t3,$a3,$bi		// lo(a[3]*b[i])
	adc	$acc4,$acc5,xzr

	adds	$acc0,$acc0,$t0		// accumulate low parts of multiplication
	 umulh	$t0,$a0,$bi		// hi(a[0]*b[i])
	adcs	$acc1,$acc1,$t1
	 umulh	$t1,$a1,$bi		// hi(a[1]*b[i])
	adcs	$acc2,$acc2,$t2
	 umulh	$t2,$a2,$bi		// hi(a[2]*b[i])
	adcs	$acc3,$acc3,$t3
	 umulh	$t3,$a3,$bi		// hi(a[3]*b[i])
	adc	$acc4,$acc4,xzr
___
$code.=<<___	if ($i<3);
	ldr	$bi,[$bp,#8*($i+1)]	// b[$i+1]
___
$code.=<<___;
	adds	$acc1,$acc1,$t0		// accumulate high parts of multiplication
	 lsl	$t0,$acc0,#32
	adcs	$acc2,$acc2,$t1
	 lsr	$t1,$acc0,#32
	adcs	$acc3,$acc3,$t2
	adcs	$acc4,$acc4,$t3
	adc	$acc5,xzr,xzr
___
}
$code.=<<___;
	// last reduction
	subs	$t2,$acc0,$t0		// "*0xffff0001"
	sbc	$t3,$acc0,$t1
	adds	$acc0,$acc1,$t0		// +=acc[0]<<96 and omit acc[0]
	adcs	$acc1,$acc2,$t1
	adcs	$acc2,$acc3,$t2		// +=acc[0]*0xffff0001
	adcs	$acc3,$acc4,$t3
	adc	$acc4,$acc5,xzr

	adds	$t0,$acc0,#1		// subs	$t0,$acc0,#-1 // tmp = ret-modulus
	sbcs	$t1,$acc1,$poly1
	sbcs	$t2,$acc2,xzr
	sbcs	$t3,$acc3,$poly3
	sbcs	xzr,$acc4,xzr		// did it borrow?

	csel	$acc0,$acc0,$t0,lo	// ret = borrow ? ret : ret-modulus
	csel	$acc1,$acc1,$t1,lo
	csel	$acc2,$acc2,$t2,lo
	stp	$acc0,$acc1,[$rp]
	csel	$acc3,$acc3,$t3,lo
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_mul_mont,.-__ecp_nistz256_mul_mont

// note that __ecp_nistz256_sqr_mont expects a[0-3] input pre-loaded
// to $a0-$a3
.type	__ecp_nistz256_sqr_mont,%function
.align	4
__ecp_nistz256_sqr_mont:
	//  |  |  |  |  |  |a1*a0|  |
	//  |  |  |  |  |a2*a0|  |  |
	//  |  |a3*a2|a3*a0|  |  |  |
	//  |  |  |  |a2*a1|  |  |  |
	//  |  |  |a3*a1|  |  |  |  |
	// *|  |  |  |  |  |  |  | 2|
	// +|a3*a3|a2*a2|a1*a1|a0*a0|
	//  |--+--+--+--+--+--+--+--|
	//  |A7|A6|A5|A4|A3|A2|A1|A0|, where Ax is $accx, i.e. follow $accx
	//
	//  "can't overflow" below mark carrying into high part of
	//  multiplication result, which can't overflow, because it
	//  can never be all ones.

	mul	$acc1,$a1,$a0		// a[1]*a[0]
	umulh	$t1,$a1,$a0
	mul	$acc2,$a2,$a0		// a[2]*a[0]
	umulh	$t2,$a2,$a0
	mul	$acc3,$a3,$a0		// a[3]*a[0]
	umulh	$acc4,$a3,$a0

	adds	$acc2,$acc2,$t1		// accumulate high parts of multiplication
	 mul	$t0,$a2,$a1		// a[2]*a[1]
	 umulh	$t1,$a2,$a1
	adcs	$acc3,$acc3,$t2
	 mul	$t2,$a3,$a1		// a[3]*a[1]
	 umulh	$t3,$a3,$a1
	adc	$acc4,$acc4,xzr		// can't overflow

	mul	$acc5,$a3,$a2		// a[3]*a[2]
	umulh	$acc6,$a3,$a2

	adds	$t1,$t1,$t2		// accumulate high parts of multiplication
	 mul	$acc0,$a0,$a0		// a[0]*a[0]
	adc	$t2,$t3,xzr		// can't overflow

	adds	$acc3,$acc3,$t0		// accumulate low parts of multiplication
	 umulh	$a0,$a0,$a0
	adcs	$acc4,$acc4,$t1
	 mul	$t1,$a1,$a1		// a[1]*a[1]
	adcs	$acc5,$acc5,$t2
	 umulh	$a1,$a1,$a1
	adc	$acc6,$acc6,xzr		// can't overflow

	adds	$acc1,$acc1,$acc1	// acc[1-6]*=2
	 mul	$t2,$a2,$a2		// a[2]*a[2]
	adcs	$acc2,$acc2,$acc2
	 umulh	$a2,$a2,$a2
	adcs	$acc3,$acc3,$acc3
	 mul	$t3,$a3,$a3		// a[3]*a[3]
	adcs	$acc4,$acc4,$acc4
	 umulh	$a3,$a3,$a3
	adcs	$acc5,$acc5,$acc5
	adcs	$acc6,$acc6,$acc6
	adc	$acc7,xzr,xzr

	adds	$acc1,$acc1,$a0		// +a[i]*a[i]
	adcs	$acc2,$acc2,$t1
	adcs	$acc3,$acc3,$a1
	adcs	$acc4,$acc4,$t2
	adcs	$acc5,$acc5,$a2
	 lsl	$t0,$acc0,#32
	adcs	$acc6,$acc6,$t3
	 lsr	$t1,$acc0,#32
	adc	$acc7,$acc7,$a3
___
for($i=0;$i<3;$i++) {			# reductions, see commentary in
					# multiplication for details
$code.=<<___;
	subs	$t2,$acc0,$t0		// "*0xffff0001"
	sbc	$t3,$acc0,$t1
	adds	$acc0,$acc1,$t0		// +=acc[0]<<96 and omit acc[0]
	adcs	$acc1,$acc2,$t1
	 lsl	$t0,$acc0,#32
	adcs	$acc2,$acc3,$t2		// +=acc[0]*0xffff0001
	 lsr	$t1,$acc0,#32
	adc	$acc3,$t3,xzr		// can't overflow
___
}
$code.=<<___;
	subs	$t2,$acc0,$t0		// "*0xffff0001"
	sbc	$t3,$acc0,$t1
	adds	$acc0,$acc1,$t0		// +=acc[0]<<96 and omit acc[0]
	adcs	$acc1,$acc2,$t1
	adcs	$acc2,$acc3,$t2		// +=acc[0]*0xffff0001
	adc	$acc3,$t3,xzr		// can't overflow

	adds	$acc0,$acc0,$acc4	// accumulate upper half
	adcs	$acc1,$acc1,$acc5
	adcs	$acc2,$acc2,$acc6
	adcs	$acc3,$acc3,$acc7
	adc	$acc4,xzr,xzr

	adds	$t0,$acc0,#1		// subs	$t0,$acc0,#-1 // tmp = ret-modulus
	sbcs	$t1,$acc1,$poly1
	sbcs	$t2,$acc2,xzr
	sbcs	$t3,$acc3,$poly3
	sbcs	xzr,$acc4,xzr		// did it borrow?

	csel	$acc0,$acc0,$t0,lo	// ret = borrow ? ret : ret-modulus
	csel	$acc1,$acc1,$t1,lo
	csel	$acc2,$acc2,$t2,lo
	stp	$acc0,$acc1,[$rp]
	csel	$acc3,$acc3,$t3,lo
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_sqr_mont,.-__ecp_nistz256_sqr_mont

// Note that __ecp_nistz256_add expects both input vectors pre-loaded to
// $a0-$a3 and $t0-$t3. This is done because it's used in multiple
// contexts, e.g. in multiplication by 2 and 3...
.type	__ecp_nistz256_add,%function
.align	4
__ecp_nistz256_add:
	adds	$acc0,$acc0,$t0		// ret = a+b
	adcs	$acc1,$acc1,$t1
	adcs	$acc2,$acc2,$t2
	adcs	$acc3,$acc3,$t3
	adc	$ap,xzr,xzr		// zap $ap

	adds	$t0,$acc0,#1		// subs	$t0,$a0,#-1 // tmp = ret-modulus
	sbcs	$t1,$acc1,$poly1
	sbcs	$t2,$acc2,xzr
	sbcs	$t3,$acc3,$poly3
	sbcs	xzr,$ap,xzr		// did subtraction borrow?

	csel	$acc0,$acc0,$t0,lo	// ret = borrow ? ret : ret-modulus
	csel	$acc1,$acc1,$t1,lo
	csel	$acc2,$acc2,$t2,lo
	stp	$acc0,$acc1,[$rp]
	csel	$acc3,$acc3,$t3,lo
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_add,.-__ecp_nistz256_add

.type	__ecp_nistz256_sub_from,%function
.align	4
__ecp_nistz256_sub_from:
	ldp	$t0,$t1,[$bp]
	ldp	$t2,$t3,[$bp,#16]
	subs	$acc0,$acc0,$t0		// ret = a-b
	sbcs	$acc1,$acc1,$t1
	sbcs	$acc2,$acc2,$t2
	sbcs	$acc3,$acc3,$t3
	sbc	$ap,xzr,xzr		// zap $ap

	subs	$t0,$acc0,#1		// adds	$t0,$a0,#-1 // tmp = ret+modulus
	adcs	$t1,$acc1,$poly1
	adcs	$t2,$acc2,xzr
	adc	$t3,$acc3,$poly3
	cmp	$ap,xzr			// did subtraction borrow?

	csel	$acc0,$acc0,$t0,eq	// ret = borrow ? ret+modulus : ret
	csel	$acc1,$acc1,$t1,eq
	csel	$acc2,$acc2,$t2,eq
	stp	$acc0,$acc1,[$rp]
	csel	$acc3,$acc3,$t3,eq
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_sub_from,.-__ecp_nistz256_sub_from

.type	__ecp_nistz256_sub_morf,%function
.align	4
__ecp_nistz256_sub_morf:
	ldp	$t0,$t1,[$bp]
	ldp	$t2,$t3,[$bp,#16]
	subs	$acc0,$t0,$acc0		// ret = b-a
	sbcs	$acc1,$t1,$acc1
	sbcs	$acc2,$t2,$acc2
	sbcs	$acc3,$t3,$acc3
	sbc	$ap,xzr,xzr		// zap $ap

	subs	$t0,$acc0,#1		// adds	$t0,$a0,#-1 // tmp = ret+modulus
	adcs	$t1,$acc1,$poly1
	adcs	$t2,$acc2,xzr
	adc	$t3,$acc3,$poly3
	cmp	$ap,xzr			// did subtraction borrow?

	csel	$acc0,$acc0,$t0,eq	// ret = borrow ? ret+modulus : ret
	csel	$acc1,$acc1,$t1,eq
	csel	$acc2,$acc2,$t2,eq
	stp	$acc0,$acc1,[$rp]
	csel	$acc3,$acc3,$t3,eq
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_sub_morf,.-__ecp_nistz256_sub_morf

.type	__ecp_nistz256_div_by_2,%function
.align	4
__ecp_nistz256_div_by_2:
	subs	$t0,$acc0,#1		// adds	$t0,$a0,#-1 // tmp = a+modulus
	adcs	$t1,$acc1,$poly1
	adcs	$t2,$acc2,xzr
	adcs	$t3,$acc3,$poly3
	adc	$ap,xzr,xzr		// zap $ap
	tst	$acc0,#1		// is a even?

	csel	$acc0,$acc0,$t0,eq	// ret = even ? a : a+modulus 
	csel	$acc1,$acc1,$t1,eq
	csel	$acc2,$acc2,$t2,eq
	csel	$acc3,$acc3,$t3,eq
	csel	$ap,xzr,$ap,eq

	lsr	$acc0,$acc0,#1		// ret >>= 1
	orr	$acc0,$acc0,$acc1,lsl#63
	lsr	$acc1,$acc1,#1
	orr	$acc1,$acc1,$acc2,lsl#63
	lsr	$acc2,$acc2,#1
	orr	$acc2,$acc2,$acc3,lsl#63
	lsr	$acc3,$acc3,#1
	stp	$acc0,$acc1,[$rp]
	orr	$acc3,$acc3,$ap,lsl#63
	stp	$acc2,$acc3,[$rp,#16]

	ret
.size	__ecp_nistz256_div_by_2,.-__ecp_nistz256_div_by_2
___
########################################################################
# following subroutines are "literal" implementation of those found in
# ecp_nistz256.c
#
########################################################################
# void ecp_nistz256_point_double(P256_POINT *out,const P256_POINT *inp);
#
{
my ($S,$M,$Zsqr,$tmp0)=map(32*$_,(0..3));
# above map() describes stack layout with 4 temporary
# 256-bit vectors on top.
my ($rp_real,$ap_real) = map("x$_",(21,22));

$code.=<<___;
.globl	ecp_nistz256_point_double
.type	ecp_nistz256_point_double,%function
.align	5
ecp_nistz256_point_double:
	stp	x29,x30,[sp,#-80]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]
	stp	x21,x22,[sp,#32]
	sub	sp,sp,#32*4

.Ldouble_shortcut:
	ldp	$acc0,$acc1,[$ap,#32]
	 mov	$rp_real,$rp
	ldp	$acc2,$acc3,[$ap,#48]
	 mov	$ap_real,$ap
	 ldr	$poly1,.Lpoly+8
	mov	$t0,$acc0
	 ldr	$poly3,.Lpoly+24
	mov	$t1,$acc1
	 ldp	$a0,$a1,[$ap_real,#64]	// forward load for p256_sqr_mont
	mov	$t2,$acc2
	mov	$t3,$acc3
	 ldp	$a2,$a3,[$ap_real,#64+16]
	add	$rp,sp,#$S
	bl	__ecp_nistz256_add	// p256_mul_by_2(S, in_y);

	add	$rp,sp,#$Zsqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Zsqr, in_z);

	ldp	$t0,$t1,[$ap_real]
	ldp	$t2,$t3,[$ap_real,#16]
	mov	$a0,$acc0		// put Zsqr aside for p256_sub
	mov	$a1,$acc1
	mov	$a2,$acc2
	mov	$a3,$acc3
	add	$rp,sp,#$M
	bl	__ecp_nistz256_add	// p256_add(M, Zsqr, in_x);

	add	$bp,$ap_real,#0
	mov	$acc0,$a0		// restore Zsqr
	mov	$acc1,$a1
	 ldp	$a0,$a1,[sp,#$S]	// forward load for p256_sqr_mont
	mov	$acc2,$a2
	mov	$acc3,$a3
	 ldp	$a2,$a3,[sp,#$S+16]
	add	$rp,sp,#$Zsqr
	bl	__ecp_nistz256_sub_morf	// p256_sub(Zsqr, in_x, Zsqr);

	add	$rp,sp,#$S
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(S, S);

	ldr	$bi,[$ap_real,#32]
	ldp	$a0,$a1,[$ap_real,#64]
	ldp	$a2,$a3,[$ap_real,#64+16]
	add	$bp,$ap_real,#32
	add	$rp,sp,#$tmp0
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(tmp0, in_z, in_y);

	mov	$t0,$acc0
	mov	$t1,$acc1
	 ldp	$a0,$a1,[sp,#$S]	// forward load for p256_sqr_mont
	mov	$t2,$acc2
	mov	$t3,$acc3
	 ldp	$a2,$a3,[sp,#$S+16]
	add	$rp,$rp_real,#64
	bl	__ecp_nistz256_add	// p256_mul_by_2(res_z, tmp0);

	add	$rp,sp,#$tmp0
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(tmp0, S);

	 ldr	$bi,[sp,#$Zsqr]		// forward load for p256_mul_mont
	 ldp	$a0,$a1,[sp,#$M]
	 ldp	$a2,$a3,[sp,#$M+16]
	add	$rp,$rp_real,#32
	bl	__ecp_nistz256_div_by_2	// p256_div_by_2(res_y, tmp0);

	add	$bp,sp,#$Zsqr
	add	$rp,sp,#$M
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(M, M, Zsqr);

	mov	$t0,$acc0		// duplicate M
	mov	$t1,$acc1
	mov	$t2,$acc2
	mov	$t3,$acc3
	mov	$a0,$acc0		// put M aside
	mov	$a1,$acc1
	mov	$a2,$acc2
	mov	$a3,$acc3
	add	$rp,sp,#$M
	bl	__ecp_nistz256_add
	mov	$t0,$a0			// restore M
	mov	$t1,$a1
	 ldr	$bi,[$ap_real]		// forward load for p256_mul_mont
	mov	$t2,$a2
	 ldp	$a0,$a1,[sp,#$S]
	mov	$t3,$a3
	 ldp	$a2,$a3,[sp,#$S+16]
	bl	__ecp_nistz256_add	// p256_mul_by_3(M, M);

	add	$bp,$ap_real,#0
	add	$rp,sp,#$S
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S, S, in_x);

	mov	$t0,$acc0
	mov	$t1,$acc1
	 ldp	$a0,$a1,[sp,#$M]	// forward load for p256_sqr_mont
	mov	$t2,$acc2
	mov	$t3,$acc3
	 ldp	$a2,$a3,[sp,#$M+16]
	add	$rp,sp,#$tmp0
	bl	__ecp_nistz256_add	// p256_mul_by_2(tmp0, S);

	add	$rp,$rp_real,#0
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(res_x, M);

	add	$bp,sp,#$tmp0
	bl	__ecp_nistz256_sub_from	// p256_sub(res_x, res_x, tmp0);

	add	$bp,sp,#$S
	add	$rp,sp,#$S
	bl	__ecp_nistz256_sub_morf	// p256_sub(S, S, res_x);

	ldr	$bi,[sp,#$M]
	mov	$a0,$acc0		// copy S
	mov	$a1,$acc1
	mov	$a2,$acc2
	mov	$a3,$acc3
	add	$bp,sp,#$M
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S, S, M);

	add	$bp,$rp_real,#32
	add	$rp,$rp_real,#32
	bl	__ecp_nistz256_sub_from	// p256_sub(res_y, S, res_y);

	add	sp,x29,#0		// destroy frame
	ldp	x19,x20,[x29,#16]
	ldp	x21,x22,[x29,#32]
	ldp	x29,x30,[sp],#80
	ret
.size	ecp_nistz256_point_double,.-ecp_nistz256_point_double
___
}

########################################################################
# void ecp_nistz256_point_add(P256_POINT *out,const P256_POINT *in1,
#			      const P256_POINT *in2);
{
my ($res_x,$res_y,$res_z,
    $H,$Hsqr,$R,$Rsqr,$Hcub,
    $U1,$U2,$S1,$S2)=map(32*$_,(0..11));
my ($Z1sqr, $Z2sqr) = ($Hsqr, $Rsqr);
# above map() describes stack layout with 12 temporary
# 256-bit vectors on top.
my ($rp_real,$ap_real,$bp_real,$in1infty,$in2infty,$temp)=map("x$_",(21..26));

$code.=<<___;
.globl	ecp_nistz256_point_add
.type	ecp_nistz256_point_add,%function
.align	5
ecp_nistz256_point_add:
	stp	x29,x30,[sp,#-80]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]
	stp	x21,x22,[sp,#32]
	stp	x23,x24,[sp,#48]
	stp	x25,x26,[sp,#64]
	sub	sp,sp,#32*12

	ldp	$a0,$a1,[$bp,#64]	// in2_z
	ldp	$a2,$a3,[$bp,#64+16]
	 mov	$rp_real,$rp
	 mov	$ap_real,$ap
	 mov	$bp_real,$bp
	 ldr	$poly1,.Lpoly+8
	 ldr	$poly3,.Lpoly+24
	orr	$t0,$a0,$a1
	orr	$t2,$a2,$a3
	orr	$in2infty,$t0,$t2
	cmp	$in2infty,#0
	csetm	$in2infty,ne		// !in2infty
	add	$rp,sp,#$Z2sqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Z2sqr, in2_z);

	ldp	$a0,$a1,[$ap_real,#64]	// in1_z
	ldp	$a2,$a3,[$ap_real,#64+16]
	orr	$t0,$a0,$a1
	orr	$t2,$a2,$a3
	orr	$in1infty,$t0,$t2
	cmp	$in1infty,#0
	csetm	$in1infty,ne		// !in1infty
	add	$rp,sp,#$Z1sqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Z1sqr, in1_z);

	ldr	$bi,[$bp_real,#64]
	ldp	$a0,$a1,[sp,#$Z2sqr]
	ldp	$a2,$a3,[sp,#$Z2sqr+16]
	add	$bp,$bp_real,#64
	add	$rp,sp,#$S1
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S1, Z2sqr, in2_z);

	ldr	$bi,[$ap_real,#64]
	ldp	$a0,$a1,[sp,#$Z1sqr]
	ldp	$a2,$a3,[sp,#$Z1sqr+16]
	add	$bp,$ap_real,#64
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, Z1sqr, in1_z);

	ldr	$bi,[$ap_real,#32]
	ldp	$a0,$a1,[sp,#$S1]
	ldp	$a2,$a3,[sp,#$S1+16]
	add	$bp,$ap_real,#32
	add	$rp,sp,#$S1
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S1, S1, in1_y);

	ldr	$bi,[$bp_real,#32]
	ldp	$a0,$a1,[sp,#$S2]
	ldp	$a2,$a3,[sp,#$S2+16]
	add	$bp,$bp_real,#32
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, S2, in2_y);

	add	$bp,sp,#$S1
	 ldr	$bi,[sp,#$Z2sqr]	// forward load for p256_mul_mont
	 ldp	$a0,$a1,[$ap_real]
	 ldp	$a2,$a3,[$ap_real,#16]
	add	$rp,sp,#$R
	bl	__ecp_nistz256_sub_from	// p256_sub(R, S2, S1);

	orr	$acc0,$acc0,$acc1	// see if result is zero
	orr	$acc2,$acc2,$acc3
	orr	$temp,$acc0,$acc2

	add	$bp,sp,#$Z2sqr
	add	$rp,sp,#$U1
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(U1, in1_x, Z2sqr);

	ldr	$bi,[sp,#$Z1sqr]
	ldp	$a0,$a1,[$bp_real]
	ldp	$a2,$a3,[$bp_real,#16]
	add	$bp,sp,#$Z1sqr
	add	$rp,sp,#$U2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(U2, in2_x, Z1sqr);

	add	$bp,sp,#$U1
	 ldp	$a0,$a1,[sp,#$R]	// forward load for p256_sqr_mont
	 ldp	$a2,$a3,[sp,#$R+16]
	add	$rp,sp,#$H
	bl	__ecp_nistz256_sub_from	// p256_sub(H, U2, U1);

	orr	$acc0,$acc0,$acc1	// see if result is zero
	orr	$acc2,$acc2,$acc3
	orr	$acc0,$acc0,$acc2
	tst	$acc0,$acc0
	b.ne	.Ladd_proceed		// is_equal(U1,U2)?

	tst	$in1infty,$in2infty
	b.eq	.Ladd_proceed		// (in1infty || in2infty)?

	tst	$temp,$temp
	b.eq	.Ladd_double		// is_equal(S1,S2)?

	eor	$a0,$a0,$a0
	eor	$a1,$a1,$a1
	stp	$a0,$a1,[$rp_real]
	stp	$a0,$a1,[$rp_real,#16]
	stp	$a0,$a1,[$rp_real,#32]
	stp	$a0,$a1,[$rp_real,#48]
	stp	$a0,$a1,[$rp_real,#64]
	stp	$a0,$a1,[$rp_real,#80]
	b	.Ladd_done

.align	4
.Ladd_double:
	mov	$ap,$ap_real
	mov	$rp,$rp_real
	ldp	x23,x24,[x29,#48]
	ldp	x25,x26,[x29,#64]
	add	sp,sp,#32*(12-4)	// difference in stack frames
	b	.Ldouble_shortcut

.align	4
.Ladd_proceed:
	add	$rp,sp,#$Rsqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Rsqr, R);

	ldr	$bi,[$ap_real,#64]
	ldp	$a0,$a1,[sp,#$H]
	ldp	$a2,$a3,[sp,#$H+16]
	add	$bp,$ap_real,#64
	add	$rp,sp,#$res_z
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(res_z, H, in1_z);

	ldp	$a0,$a1,[sp,#$H]
	ldp	$a2,$a3,[sp,#$H+16]
	add	$rp,sp,#$Hsqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Hsqr, H);

	ldr	$bi,[$bp_real,#64]
	ldp	$a0,$a1,[sp,#$res_z]
	ldp	$a2,$a3,[sp,#$res_z+16]
	add	$bp,$bp_real,#64
	add	$rp,sp,#$res_z
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(res_z, res_z, in2_z);

	ldr	$bi,[sp,#$H]
	ldp	$a0,$a1,[sp,#$Hsqr]
	ldp	$a2,$a3,[sp,#$Hsqr+16]
	add	$bp,sp,#$H
	add	$rp,sp,#$Hcub
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(Hcub, Hsqr, H);

	ldr	$bi,[sp,#$Hsqr]
	ldp	$a0,$a1,[sp,#$U1]
	ldp	$a2,$a3,[sp,#$U1+16]
	add	$bp,sp,#$Hsqr
	add	$rp,sp,#$U2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(U2, U1, Hsqr);

	mov	$t0,$acc0
	mov	$t1,$acc1
	mov	$t2,$acc2
	mov	$t3,$acc3
	add	$rp,sp,#$Hsqr
	bl	__ecp_nistz256_add	// p256_mul_by_2(Hsqr, U2);

	add	$bp,sp,#$Rsqr
	add	$rp,sp,#$res_x
	bl	__ecp_nistz256_sub_morf	// p256_sub(res_x, Rsqr, Hsqr);

	add	$bp,sp,#$Hcub
	bl	__ecp_nistz256_sub_from	//  p256_sub(res_x, res_x, Hcub);

	add	$bp,sp,#$U2
	 ldr	$bi,[sp,#$Hcub]		// forward load for p256_mul_mont
	 ldp	$a0,$a1,[sp,#$S1]
	 ldp	$a2,$a3,[sp,#$S1+16]
	add	$rp,sp,#$res_y
	bl	__ecp_nistz256_sub_morf	// p256_sub(res_y, U2, res_x);

	add	$bp,sp,#$Hcub
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, S1, Hcub);

	ldr	$bi,[sp,#$R]
	ldp	$a0,$a1,[sp,#$res_y]
	ldp	$a2,$a3,[sp,#$res_y+16]
	add	$bp,sp,#$R
	add	$rp,sp,#$res_y
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(res_y, res_y, R);

	add	$bp,sp,#$S2
	bl	__ecp_nistz256_sub_from	// p256_sub(res_y, res_y, S2);

	ldp	$a0,$a1,[sp,#$res_x]		// res
	ldp	$a2,$a3,[sp,#$res_x+16]
	ldp	$t0,$t1,[$bp_real]		// in2
	ldp	$t2,$t3,[$bp_real,#16]
___
for($i=0;$i<64;$i+=32) {		# conditional moves
$code.=<<___;
	ldp	$acc0,$acc1,[$ap_real,#$i]	// in1
	cmp	$in1infty,#0			// !$in1intfy, remember?
	ldp	$acc2,$acc3,[$ap_real,#$i+16]
	csel	$t0,$a0,$t0,ne
	csel	$t1,$a1,$t1,ne
	ldp	$a0,$a1,[sp,#$res_x+$i+32]	// res
	csel	$t2,$a2,$t2,ne
	csel	$t3,$a3,$t3,ne
	cmp	$in2infty,#0			// !$in2intfy, remember?
	ldp	$a2,$a3,[sp,#$res_x+$i+48]
	csel	$acc0,$t0,$acc0,ne
	csel	$acc1,$t1,$acc1,ne
	ldp	$t0,$t1,[$bp_real,#$i+32]	// in2
	csel	$acc2,$t2,$acc2,ne
	csel	$acc3,$t3,$acc3,ne
	ldp	$t2,$t3,[$bp_real,#$i+48]
	stp	$acc0,$acc1,[$rp_real,#$i]
	stp	$acc2,$acc3,[$rp_real,#$i+16]
___
}
$code.=<<___;
	ldp	$acc0,$acc1,[$ap_real,#$i]	// in1
	cmp	$in1infty,#0			// !$in1intfy, remember?
	ldp	$acc2,$acc3,[$ap_real,#$i+16]
	csel	$t0,$a0,$t0,ne
	csel	$t1,$a1,$t1,ne
	csel	$t2,$a2,$t2,ne
	csel	$t3,$a3,$t3,ne
	cmp	$in2infty,#0			// !$in2intfy, remember?
	csel	$acc0,$t0,$acc0,ne
	csel	$acc1,$t1,$acc1,ne
	csel	$acc2,$t2,$acc2,ne
	csel	$acc3,$t3,$acc3,ne
	stp	$acc0,$acc1,[$rp_real,#$i]
	stp	$acc2,$acc3,[$rp_real,#$i+16]

.Ladd_done:
	add	sp,x29,#0	// destroy frame
	ldp	x19,x20,[x29,#16]
	ldp	x21,x22,[x29,#32]
	ldp	x23,x24,[x29,#48]
	ldp	x25,x26,[x29,#64]
	ldp	x29,x30,[sp],#80
	ret
.size	ecp_nistz256_point_add,.-ecp_nistz256_point_add
___
}

########################################################################
# void ecp_nistz256_point_add_affine(P256_POINT *out,const P256_POINT *in1,
#				     const P256_POINT_AFFINE *in2);
{
my ($res_x,$res_y,$res_z,
    $U2,$S2,$H,$R,$Hsqr,$Hcub,$Rsqr)=map(32*$_,(0..9));
my $Z1sqr = $S2;
# above map() describes stack layout with 10 temporary
# 256-bit vectors on top.
my ($rp_real,$ap_real,$bp_real,$in1infty,$in2infty,$temp)=map("x$_",(21..26));

$code.=<<___;
.globl	ecp_nistz256_point_add_affine
.type	ecp_nistz256_point_add_affine,%function
.align	5
ecp_nistz256_point_add_affine:
	stp	x29,x30,[sp,#-80]!
	add	x29,sp,#0
	stp	x19,x20,[sp,#16]
	stp	x21,x22,[sp,#32]
	stp	x23,x24,[sp,#48]
	stp	x25,x26,[sp,#64]
	sub	sp,sp,#32*10

	mov	$rp_real,$rp
	mov	$ap_real,$ap
	mov	$bp_real,$bp
	ldr	$poly1,.Lpoly+8
	ldr	$poly3,.Lpoly+24

	ldp	$a0,$a1,[$ap,#64]	// in1_z
	ldp	$a2,$a3,[$ap,#64+16]
	orr	$t0,$a0,$a1
	orr	$t2,$a2,$a3
	orr	$in1infty,$t0,$t2
	cmp	$in1infty,#0
	csetm	$in1infty,ne		// !in1infty

	ldp	$acc0,$acc1,[$bp]	// in2_x
	ldp	$acc2,$acc3,[$bp,#16]
	ldp	$t0,$t1,[$bp,#32]	// in2_y
	ldp	$t2,$t3,[$bp,#48]
	orr	$acc0,$acc0,$acc1
	orr	$acc2,$acc2,$acc3
	orr	$t0,$t0,$t1
	orr	$t2,$t2,$t3
	orr	$acc0,$acc0,$acc2
	orr	$t0,$t0,$t2
	orr	$in2infty,$acc0,$t0
	cmp	$in2infty,#0
	csetm	$in2infty,ne		// !in2infty

	add	$rp,sp,#$Z1sqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Z1sqr, in1_z);

	mov	$a0,$acc0
	mov	$a1,$acc1
	mov	$a2,$acc2
	mov	$a3,$acc3
	ldr	$bi,[$bp_real]
	add	$bp,$bp_real,#0
	add	$rp,sp,#$U2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(U2, Z1sqr, in2_x);

	add	$bp,$ap_real,#0
	 ldr	$bi,[$ap_real,#64]	// forward load for p256_mul_mont
	 ldp	$a0,$a1,[sp,#$Z1sqr]
	 ldp	$a2,$a3,[sp,#$Z1sqr+16]
	add	$rp,sp,#$H
	bl	__ecp_nistz256_sub_from	// p256_sub(H, U2, in1_x);

	add	$bp,$ap_real,#64
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, Z1sqr, in1_z);

	ldr	$bi,[$ap_real,#64]
	ldp	$a0,$a1,[sp,#$H]
	ldp	$a2,$a3,[sp,#$H+16]
	add	$bp,$ap_real,#64
	add	$rp,sp,#$res_z
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(res_z, H, in1_z);

	ldr	$bi,[$bp_real,#32]
	ldp	$a0,$a1,[sp,#$S2]
	ldp	$a2,$a3,[sp,#$S2+16]
	add	$bp,$bp_real,#32
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, S2, in2_y);

	add	$bp,$ap_real,#32
	 ldp	$a0,$a1,[sp,#$H]	// forward load for p256_sqr_mont
	 ldp	$a2,$a3,[sp,#$H+16]
	add	$rp,sp,#$R
	bl	__ecp_nistz256_sub_from	// p256_sub(R, S2, in1_y);

	add	$rp,sp,#$Hsqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Hsqr, H);

	ldp	$a0,$a1,[sp,#$R]
	ldp	$a2,$a3,[sp,#$R+16]
	add	$rp,sp,#$Rsqr
	bl	__ecp_nistz256_sqr_mont	// p256_sqr_mont(Rsqr, R);

	ldr	$bi,[sp,#$H]
	ldp	$a0,$a1,[sp,#$Hsqr]
	ldp	$a2,$a3,[sp,#$Hsqr+16]
	add	$bp,sp,#$H
	add	$rp,sp,#$Hcub
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(Hcub, Hsqr, H);

	ldr	$bi,[$ap_real]
	ldp	$a0,$a1,[sp,#$Hsqr]
	ldp	$a2,$a3,[sp,#$Hsqr+16]
	add	$bp,$ap_real,#0
	add	$rp,sp,#$U2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(U2, in1_x, Hsqr);

	mov	$t0,$acc0
	mov	$t1,$acc1
	mov	$t2,$acc2
	mov	$t3,$acc3
	add	$rp,sp,#$Hsqr
	bl	__ecp_nistz256_add	// p256_mul_by_2(Hsqr, U2);

	add	$bp,sp,#$Rsqr
	add	$rp,sp,#$res_x
	bl	__ecp_nistz256_sub_morf	// p256_sub(res_x, Rsqr, Hsqr);

	add	$bp,sp,#$Hcub
	bl	__ecp_nistz256_sub_from	//  p256_sub(res_x, res_x, Hcub);

	add	$bp,sp,#$U2
	 ldr	$bi,[$ap_real,#32]	// forward load for p256_mul_mont
	 ldp	$a0,$a1,[sp,#$Hcub]
	 ldp	$a2,$a3,[sp,#$Hcub+16]
	add	$rp,sp,#$res_y
	bl	__ecp_nistz256_sub_morf	// p256_sub(res_y, U2, res_x);

	add	$bp,$ap_real,#32
	add	$rp,sp,#$S2
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(S2, in1_y, Hcub);

	ldr	$bi,[sp,#$R]
	ldp	$a0,$a1,[sp,#$res_y]
	ldp	$a2,$a3,[sp,#$res_y+16]
	add	$bp,sp,#$R
	add	$rp,sp,#$res_y
	bl	__ecp_nistz256_mul_mont	// p256_mul_mont(res_y, res_y, R);

	add	$bp,sp,#$S2
	bl	__ecp_nistz256_sub_from	// p256_sub(res_y, res_y, S2);

	ldp	$a0,$a1,[sp,#$res_x]		// res
	ldp	$a2,$a3,[sp,#$res_x+16]
	ldp	$t0,$t1,[$bp_real]		// in2
	ldp	$t2,$t3,[$bp_real,#16]
___
for($i=0;$i<64;$i+=32) {		# conditional moves
$code.=<<___;
	ldp	$acc0,$acc1,[$ap_real,#$i]	// in1
	cmp	$in1infty,#0			// !$in1intfy, remember?
	ldp	$acc2,$acc3,[$ap_real,#$i+16]
	csel	$t0,$a0,$t0,ne
	csel	$t1,$a1,$t1,ne
	ldp	$a0,$a1,[sp,#$res_x+$i+32]	// res
	csel	$t2,$a2,$t2,ne
	csel	$t3,$a3,$t3,ne
	cmp	$in2infty,#0			// !$in2intfy, remember?
	ldp	$a2,$a3,[sp,#$res_x+$i+48]
	csel	$acc0,$t0,$acc0,ne
	csel	$acc1,$t1,$acc1,ne
	ldp	$t0,$t1,[$bp_real,#$i+32]	// in2
	csel	$acc2,$t2,$acc2,ne
	csel	$acc3,$t3,$acc3,ne
	ldp	$t2,$t3,[$bp_real,#$i+48]
	stp	$acc0,$acc1,[$rp_real,#$i]
	stp	$acc2,$acc3,[$rp_real,#$i+16]
___
$code.=<<___	if ($i == 0);
	adr	$bp_real,.Lone_mont-64
___
}
$code.=<<___;
	ldp	$acc0,$acc1,[$ap_real,#$i]	// in1
	cmp	$in1infty,#0			// !$in1intfy, remember?
	ldp	$acc2,$acc3,[$ap_real,#$i+16]
	csel	$t0,$a0,$t0,ne
	csel	$t1,$a1,$t1,ne
	csel	$t2,$a2,$t2,ne
	csel	$t3,$a3,$t3,ne
	cmp	$in2infty,#0			// !$in2intfy, remember?
	csel	$acc0,$t0,$acc0,ne
	csel	$acc1,$t1,$acc1,ne
	csel	$acc2,$t2,$acc2,ne
	csel	$acc3,$t3,$acc3,ne
	stp	$acc0,$acc1,[$rp_real,#$i]
	stp	$acc2,$acc3,[$rp_real,#$i+16]

	add	sp,x29,#0		// destroy frame
	ldp	x19,x20,[x29,#16]
	ldp	x21,x22,[x29,#32]
	ldp	x23,x24,[x29,#48]
	ldp	x25,x26,[x29,#64]
	ldp	x29,x30,[sp],#80
	ret
.size	ecp_nistz256_point_add_affine,.-ecp_nistz256_point_add_affine
___
}	}

########################################################################
# scatter-gather subroutines
{
my ($out,$inp,$index,$mask)=map("x$_",(0..3));
$code.=<<___;
// void	ecp_nistz256_scatter_w5(void *x0,const P256_POINT *x1,
//					 int x2);
.globl	ecp_nistz256_scatter_w5
.type	ecp_nistz256_scatter_w5,%function
.align	4
ecp_nistz256_scatter_w5:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	add	$out,$out,$index,lsl#2

	ldp	x4,x5,[$inp]		// X
	ldp	x6,x7,[$inp,#16]
	str	w4,[$out,#64*0-4]
	lsr	x4,x4,#32
	str	w5,[$out,#64*1-4]
	lsr	x5,x5,#32
	str	w6,[$out,#64*2-4]
	lsr	x6,x6,#32
	str	w7,[$out,#64*3-4]
	lsr	x7,x7,#32
	str	w4,[$out,#64*4-4]
	str	w5,[$out,#64*5-4]
	str	w6,[$out,#64*6-4]
	str	w7,[$out,#64*7-4]
	add	$out,$out,#64*8

	ldp	x4,x5,[$inp,#32]	// Y
	ldp	x6,x7,[$inp,#48]
	str	w4,[$out,#64*0-4]
	lsr	x4,x4,#32
	str	w5,[$out,#64*1-4]
	lsr	x5,x5,#32
	str	w6,[$out,#64*2-4]
	lsr	x6,x6,#32
	str	w7,[$out,#64*3-4]
	lsr	x7,x7,#32
	str	w4,[$out,#64*4-4]
	str	w5,[$out,#64*5-4]
	str	w6,[$out,#64*6-4]
	str	w7,[$out,#64*7-4]
	add	$out,$out,#64*8

	ldp	x4,x5,[$inp,#64]	// Z
	ldp	x6,x7,[$inp,#80]
	str	w4,[$out,#64*0-4]
	lsr	x4,x4,#32
	str	w5,[$out,#64*1-4]
	lsr	x5,x5,#32
	str	w6,[$out,#64*2-4]
	lsr	x6,x6,#32
	str	w7,[$out,#64*3-4]
	lsr	x7,x7,#32
	str	w4,[$out,#64*4-4]
	str	w5,[$out,#64*5-4]
	str	w6,[$out,#64*6-4]
	str	w7,[$out,#64*7-4]

	ldr	x29,[sp],#16
	ret
.size	ecp_nistz256_scatter_w5,.-ecp_nistz256_scatter_w5

// void	ecp_nistz256_gather_w5(P256_POINT *x0,const void *x1,
//					      int x2);
.globl	ecp_nistz256_gather_w5
.type	ecp_nistz256_gather_w5,%function
.align	4
ecp_nistz256_gather_w5:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	cmp	$index,xzr
	csetm	x3,ne
	add	$index,$index,x3
	add	$inp,$inp,$index,lsl#2

	ldr	w4,[$inp,#64*0]
	ldr	w5,[$inp,#64*1]
	ldr	w6,[$inp,#64*2]
	ldr	w7,[$inp,#64*3]
	ldr	w8,[$inp,#64*4]
	ldr	w9,[$inp,#64*5]
	ldr	w10,[$inp,#64*6]
	ldr	w11,[$inp,#64*7]
	add	$inp,$inp,#64*8
	orr	x4,x4,x8,lsl#32
	orr	x5,x5,x9,lsl#32
	orr	x6,x6,x10,lsl#32
	orr	x7,x7,x11,lsl#32
	csel	x4,x4,xzr,ne
	csel	x5,x5,xzr,ne
	csel	x6,x6,xzr,ne
	csel	x7,x7,xzr,ne
	stp	x4,x5,[$out]		// X
	stp	x6,x7,[$out,#16]

	ldr	w4,[$inp,#64*0]
	ldr	w5,[$inp,#64*1]
	ldr	w6,[$inp,#64*2]
	ldr	w7,[$inp,#64*3]
	ldr	w8,[$inp,#64*4]
	ldr	w9,[$inp,#64*5]
	ldr	w10,[$inp,#64*6]
	ldr	w11,[$inp,#64*7]
	add	$inp,$inp,#64*8
	orr	x4,x4,x8,lsl#32
	orr	x5,x5,x9,lsl#32
	orr	x6,x6,x10,lsl#32
	orr	x7,x7,x11,lsl#32
	csel	x4,x4,xzr,ne
	csel	x5,x5,xzr,ne
	csel	x6,x6,xzr,ne
	csel	x7,x7,xzr,ne
	stp	x4,x5,[$out,#32]	// Y
	stp	x6,x7,[$out,#48]

	ldr	w4,[$inp,#64*0]
	ldr	w5,[$inp,#64*1]
	ldr	w6,[$inp,#64*2]
	ldr	w7,[$inp,#64*3]
	ldr	w8,[$inp,#64*4]
	ldr	w9,[$inp,#64*5]
	ldr	w10,[$inp,#64*6]
	ldr	w11,[$inp,#64*7]
	orr	x4,x4,x8,lsl#32
	orr	x5,x5,x9,lsl#32
	orr	x6,x6,x10,lsl#32
	orr	x7,x7,x11,lsl#32
	csel	x4,x4,xzr,ne
	csel	x5,x5,xzr,ne
	csel	x6,x6,xzr,ne
	csel	x7,x7,xzr,ne
	stp	x4,x5,[$out,#64]	// Z
	stp	x6,x7,[$out,#80]

	ldr	x29,[sp],#16
	ret
.size	ecp_nistz256_gather_w5,.-ecp_nistz256_gather_w5

// void	ecp_nistz256_scatter_w7(void *x0,const P256_POINT_AFFINE *x1,
//					 int x2);
.globl	ecp_nistz256_scatter_w7
.type	ecp_nistz256_scatter_w7,%function
.align	4
ecp_nistz256_scatter_w7:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	add	$out,$out,$index
	mov	$index,#64/8
.Loop_scatter_w7:
	ldr	x3,[$inp],#8
	subs	$index,$index,#1
	prfm	pstl1strm,[$out,#4096+64*0]
	prfm	pstl1strm,[$out,#4096+64*1]
	prfm	pstl1strm,[$out,#4096+64*2]
	prfm	pstl1strm,[$out,#4096+64*3]
	prfm	pstl1strm,[$out,#4096+64*4]
	prfm	pstl1strm,[$out,#4096+64*5]
	prfm	pstl1strm,[$out,#4096+64*6]
	prfm	pstl1strm,[$out,#4096+64*7]
	strb	w3,[$out,#64*0-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*1-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*2-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*3-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*4-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*5-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*6-1]
	lsr	x3,x3,#8
	strb	w3,[$out,#64*7-1]
	add	$out,$out,#64*8
	b.ne	.Loop_scatter_w7

	ldr	x29,[sp],#16
	ret
.size	ecp_nistz256_scatter_w7,.-ecp_nistz256_scatter_w7

// void	ecp_nistz256_gather_w7(P256_POINT_AFFINE *x0,const void *x1,
//						     int x2);
.globl	ecp_nistz256_gather_w7
.type	ecp_nistz256_gather_w7,%function
.align	4
ecp_nistz256_gather_w7:
	stp	x29,x30,[sp,#-16]!
	add	x29,sp,#0

	cmp	$index,xzr
	csetm	x3,ne
	add	$index,$index,x3
	add	$inp,$inp,$index
	mov	$index,#64/8
	nop
.Loop_gather_w7:
	ldrb	w4,[$inp,#64*0]
	prfm	pldl1strm,[$inp,#4096+64*0]
	subs	$index,$index,#1
	ldrb	w5,[$inp,#64*1]
	prfm	pldl1strm,[$inp,#4096+64*1]
	ldrb	w6,[$inp,#64*2]
	prfm	pldl1strm,[$inp,#4096+64*2]
	ldrb	w7,[$inp,#64*3]
	prfm	pldl1strm,[$inp,#4096+64*3]
	ldrb	w8,[$inp,#64*4]
	prfm	pldl1strm,[$inp,#4096+64*4]
	ldrb	w9,[$inp,#64*5]
	prfm	pldl1strm,[$inp,#4096+64*5]
	ldrb	w10,[$inp,#64*6]
	prfm	pldl1strm,[$inp,#4096+64*6]
	ldrb	w11,[$inp,#64*7]
	prfm	pldl1strm,[$inp,#4096+64*7]
	add	$inp,$inp,#64*8
	orr	x4,x4,x5,lsl#8
	orr	x6,x6,x7,lsl#8
	orr	x8,x8,x9,lsl#8
	orr	x4,x4,x6,lsl#16
	orr	x10,x10,x11,lsl#8
	orr	x4,x4,x8,lsl#32
	orr	x4,x4,x10,lsl#48
	and	x4,x4,x3
	str	x4,[$out],#8
	b.ne	.Loop_gather_w7

	ldr	x29,[sp],#16
	ret
.size	ecp_nistz256_gather_w7,.-ecp_nistz256_gather_w7
___
}

foreach (split("\n",$code)) {
	s/\`([^\`]*)\`/eval $1/ge;

	print $_,"\n";
}
close STDOUT;	# enforce flush