From 7a6c9a2e96247b0c623252f398abe123cdf1e3f8 Mon Sep 17 00:00:00 2001
From: Andy Polyakov <appro@openssl.org>
Date: Wed, 11 Feb 2015 20:34:18 +0100
Subject: [PATCH] Add ec/asm/ecp_nistz256-armv4.pl module.
MIME-Version: 1.0
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Reviewed-by: Emilia Käsper <emilia@openssl.org>
---
 crypto/ec/Makefile                  |    3 +
 crypto/ec/asm/ecp_nistz256-armv4.pl | 1809 +++++++++++++++++++++++++++
 2 files changed, 1812 insertions(+)
 create mode 100755 crypto/ec/asm/ecp_nistz256-armv4.pl

diff --git a/crypto/ec/Makefile b/crypto/ec/Makefile
index 319e0039db..7e9f7a6b52 100644
--- a/crypto/ec/Makefile
+++ b/crypto/ec/Makefile
@@ -57,6 +57,9 @@ ecp_nistz256-x86_64.s: asm/ecp_nistz256-x86_64.pl
 ecp_nistz256-avx2.s:   asm/ecp_nistz256-avx2.pl
 	$(PERL) asm/ecp_nistz256-avx2.pl $(PERLASM_SCHEME) > $@
 
+ecp_nistz256-%.S:	asm/ecp_nistz256-%.pl;  $(PERL) $< $(PERLASM_SCHEME) $@
+ecp_nistz256-armv4.o:	ecp_nistz256-armv4.S
+
 files:
 	$(PERL) $(TOP)/util/files.pl Makefile >> $(TOP)/MINFO
 
diff --git a/crypto/ec/asm/ecp_nistz256-armv4.pl b/crypto/ec/asm/ecp_nistz256-armv4.pl
new file mode 100755
index 0000000000..9f5500ebf3
--- /dev/null
+++ b/crypto/ec/asm/ecp_nistz256-armv4.pl
@@ -0,0 +1,1809 @@
+#!/usr/bin/env perl
+
+# ====================================================================
+# 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 ARMv4.
+#
+# October 2014.
+#
+# Original ECP_NISTZ256 submission targeting x86_64 is detailed in
+# http://eprint.iacr.org/2013/816. In the process of adaptation
+# original .c module was made 32-bit savvy in order to make this
+# implementation possible.
+#
+#			with/without -DECP_NISTZ256_ASM
+# Cortex-A8		+53-170%
+# Cortex-A9		+76-205%
+# Cortex-A15		+100-316%
+# Snapdragon S4		+66-187%
+#
+# Ranges denote minimum and maximum improvement coefficients depending
+# on benchmark. Lower coefficients are for ECDSA sign, server-side
+# operation. Keep in mind that +200% means 3x 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 $output";
+*STDOUT=*OUT;
+
+$code.=<<___;
+#include "arm_arch.h"
+
+.text
+.code	32
+___
+########################################################################
+# 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
+.LRR:	@ 2^512 mod P precomputed for NIST P256 polynomial
+.long	0x00000003, 0x00000000, 0xffffffff, 0xfffffffb
+.long	0xfffffffe, 0xffffffff, 0xfffffffd, 0x00000004
+.Lone:
+.long	1,0,0,0,0,0,0,0
+.asciz	"ECP_NISTZ256 for ARMv4, CRYPTOGAMS by <appro\@openssl.org>"
+.align	6
+___
+
+########################################################################
+# common register layout, note that $t2 is link register, so that if
+# internal subroutine uses $t2, then it has to offload lr...
+
+($r_ptr,$a_ptr,$b_ptr,$ff,$a0,$a1,$a2,$a3,$a4,$a5,$a6,$a7,$t1,$t2)=
+		map("r$_",(0..12,14));
+($t0,$t3)=($ff,$a_ptr);
+
+$code.=<<___;
+@ void	ecp_nistz256_to_mont(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_to_mont
+.type	ecp_nistz256_to_mont,%function
+ecp_nistz256_to_mont:
+	adr	$b_ptr,.LRR
+	b	.Lecp_nistz256_mul_mont
+.size	ecp_nistz256_to_mont,.-ecp_nistz256_to_mont
+
+@ void	ecp_nistz256_from_mont(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_from_mont
+.type	ecp_nistz256_from_mont,%function
+ecp_nistz256_from_mont:
+	adr	$b_ptr,.Lone
+	b	.Lecp_nistz256_mul_mont
+.size	ecp_nistz256_from_mont,.-ecp_nistz256_from_mont
+
+@ void	ecp_nistz256_mul_by_2(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_mul_by_2
+.type	ecp_nistz256_mul_by_2,%function
+.align	4
+ecp_nistz256_mul_by_2:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_mul_by_2
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_mul_by_2,.-ecp_nistz256_mul_by_2
+
+.type	_ecp_nistz256_mul_by_2,%function
+.align	4
+_ecp_nistz256_mul_by_2:
+	ldr	$a0,[$a_ptr,#0]
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	adds	$a0,$a0,$a0		@ a[0:7]+=a[0:7], i.e. add with itself
+	ldr	$a3,[$a_ptr,#12]
+	adcs	$a1,$a1,$a1
+	ldr	$a4,[$a_ptr,#16]
+	adcs	$a2,$a2,$a2
+	ldr	$a5,[$a_ptr,#20]
+	adcs	$a3,$a3,$a3
+	ldr	$a6,[$a_ptr,#24]
+	adcs	$a4,$a4,$a4
+	ldr	$a7,[$a_ptr,#28]
+	adcs	$a5,$a5,$a5
+	adcs	$a6,$a6,$a6
+	mov	$ff,#0
+	adcs	$a7,$a7,$a7
+	movcs	$ff,#-1			@ $ff = carry ? -1 : 0
+
+	b	.Lreduce_by_sub
+.size	_ecp_nistz256_mul_by_2,.-_ecp_nistz256_mul_by_2
+
+@ void	ecp_nistz256_add(BN_ULONG r0[8],const BN_ULONG r1[8],
+@					const BN_ULONG r2[8]);
+.globl	ecp_nistz256_add
+.type	ecp_nistz256_add,%function
+.align	4
+ecp_nistz256_add:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_add
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_add,.-ecp_nistz256_add
+
+.type	_ecp_nistz256_add,%function
+.align	4
+_ecp_nistz256_add:
+	str	lr,[sp,#-4]!		@ push lr
+
+	ldr	$a0,[$a_ptr,#0]
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	ldr	$a3,[$a_ptr,#12]
+	ldr	$a4,[$a_ptr,#16]
+	 ldr	$t0,[$b_ptr,#0]
+	ldr	$a5,[$a_ptr,#20]
+	 ldr	$t1,[$b_ptr,#4]
+	ldr	$a6,[$a_ptr,#24]
+	 ldr	$t2,[$b_ptr,#8]
+	ldr	$a7,[$a_ptr,#28]
+	 ldr	$t3,[$b_ptr,#12]
+	adds	$a0,$a0,$t0
+	 ldr	$t0,[$b_ptr,#16]
+	adcs	$a1,$a1,$t1
+	 ldr	$t1,[$b_ptr,#20]
+	adcs	$a2,$a2,$t2
+	 ldr	$t2,[$b_ptr,#24]
+	adcs	$a3,$a3,$t3
+	 ldr	$t3,[$b_ptr,#28]
+	adcs	$a4,$a4,$t0
+	adcs	$a5,$a5,$t1
+	adcs	$a6,$a6,$t2
+	mov	$ff,#0
+	adcs	$a7,$a7,$t3
+	movcs	$ff,#-1			@ $ff = carry ? -1 : 0, "broadcast" carry
+	ldr	lr,[sp],#4		@ pop lr
+
+.Lreduce_by_sub:
+
+	@ if a+b carries, subtract modulus.
+	@
+	@ Note that because mod has special form, i.e. consists of
+	@ 0xffffffff, 1 and 0s, we can conditionally synthesize it by
+	@ using value of broadcasted carry as a whole or extracting
+	@ single bit. Follow $ff register...
+
+	subs	$a0,$a0,$ff		@ subtract synthesized modulus
+	sbcs	$a1,$a1,$ff
+	str	$a0,[$r_ptr,#0]
+	sbcs	$a2,$a2,$ff
+	str	$a1,[$r_ptr,#4]
+	sbcs	$a3,$a3,#0
+	str	$a2,[$r_ptr,#8]
+	sbcs	$a4,$a4,#0
+	str	$a3,[$r_ptr,#12]
+	sbcs	$a5,$a5,#0
+	str	$a4,[$r_ptr,#16]
+	sbcs	$a6,$a6,$ff,lsr#31
+	str	$a5,[$r_ptr,#20]
+	sbcs	$a7,$a7,$ff
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	_ecp_nistz256_add,.-_ecp_nistz256_add
+
+@ void	ecp_nistz256_mul_by_3(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_mul_by_3
+.type	ecp_nistz256_mul_by_3,%function
+.align	4
+ecp_nistz256_mul_by_3:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_mul_by_3
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_mul_by_3,.-ecp_nistz256_mul_by_3
+
+.type	_ecp_nistz256_mul_by_3,%function
+.align	4
+_ecp_nistz256_mul_by_3:
+	str	lr,[sp,#-4]!		@ push lr
+
+	@ As multiplication by 3 is performed as 2*n+n, below are inline
+	@ copies of _ecp_nistz256_mul_by_2 and _ecp_nistz256_add, see
+	@ corresponding subroutines for details.
+
+	ldr	$a0,[$a_ptr,#0]
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	adds	$a0,$a0,$a0		@ a[0:7]+=a[0:7]
+	ldr	$a3,[$a_ptr,#12]
+	adcs	$a1,$a1,$a1
+	ldr	$a4,[$a_ptr,#16]
+	adcs	$a2,$a2,$a2
+	ldr	$a5,[$a_ptr,#20]
+	adcs	$a3,$a3,$a3
+	ldr	$a6,[$a_ptr,#24]
+	adcs	$a4,$a4,$a4
+	ldr	$a7,[$a_ptr,#28]
+	adcs	$a5,$a5,$a5
+	adcs	$a6,$a6,$a6
+	mov	$ff,#0
+	adcs	$a7,$a7,$a7
+	movcs	$ff,#-1			@ $ff = carry ? -1 : 0, "broadcast" carry
+
+	subs	$a0,$a0,$ff		@ subtract synthesized modulus, see
+					@ .Lreduce_by_sub for details, except
+					@ that we don't write anything to
+					@ memory, but keep intermediate
+					@ results in registers...
+	sbcs	$a1,$a1,$ff
+	sbcs	$a2,$a2,$ff
+	sbcs	$a3,$a3,#0
+	sbcs	$a4,$a4,#0
+	 ldr	$b_ptr,[$a_ptr,#0]
+	sbcs	$a5,$a5,#0
+	 ldr	$t1,[$a_ptr,#4]
+	sbcs	$a6,$a6,$ff,lsr#31
+	 ldr	$t2,[$a_ptr,#8]
+	sbcs	$a7,$a7,$ff
+
+	ldr	$t0,[$a_ptr,#12]
+	adds	$a0,$a0,$b_ptr		@ 2*a[0:7]+=a[0:7]
+	ldr	$b_ptr,[$a_ptr,#16]
+	adcs	$a1,$a1,$t1
+	ldr	$t1,[$a_ptr,#20]
+	adcs	$a2,$a2,$t2
+	ldr	$t2,[$a_ptr,#24]
+	adcs	$a3,$a3,$t0
+	ldr	$t3,[$a_ptr,#28]
+	adcs	$a4,$a4,$b_ptr
+	adcs	$a5,$a5,$t1
+	adcs	$a6,$a6,$t2
+	mov	$ff,#0
+	adcs	$a7,$a7,$t3
+	movcs	$ff,#-1			@ $ff = carry ? -1 : 0, "broadcast" carry
+	ldr	lr,[sp],#4		@ pop lr
+
+	b	.Lreduce_by_sub
+.size	ecp_nistz256_mul_by_3,.-ecp_nistz256_mul_by_3
+
+@ void	ecp_nistz256_div_by_2(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_div_by_2
+.type	ecp_nistz256_div_by_2,%function
+.align	4
+ecp_nistz256_div_by_2:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_div_by_2
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_div_by_2,.-ecp_nistz256_div_by_2
+
+.type	_ecp_nistz256_div_by_2,%function
+.align	4
+_ecp_nistz256_div_by_2:
+	@ ret = (a is odd ? a+mod : a) >> 1
+
+	ldr	$a0,[$a_ptr,#0]
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	mov	$ff,$a0,lsl#31		@ place least significant bit to most
+					@ significant position, now arithmetic
+					@ right shift by 31 will produce -1 or
+					@ 0, while logical rigth shift 1 or 0,
+					@ this is how modulus is conditionally
+					@ synthesized in this case...
+	ldr	$a3,[$a_ptr,#12]
+	adds	$a0,$a0,$ff,asr#31
+	ldr	$a4,[$a_ptr,#16]
+	adcs	$a1,$a1,$ff,asr#31
+	ldr	$a5,[$a_ptr,#20]
+	adcs	$a2,$a2,$ff,asr#31
+	ldr	$a6,[$a_ptr,#24]
+	adcs	$a3,$a3,#0
+	ldr	$a7,[$a_ptr,#28]
+	adcs	$a4,$a4,#0
+	 mov	$a0,$a0,lsr#1		@ a[0:7]>>=1, we can start early
+					@ because it doesn't affect flags
+	adcs	$a5,$a5,#0
+	 orr	$a0,$a0,$a1,lsl#31
+	adcs	$a6,$a6,$ff,lsr#31
+	mov	$b_ptr,#0
+	adcs	$a7,$a7,$ff,asr#31
+	 mov	$a1,$a1,lsr#1
+	adc	$b_ptr,$b_ptr,#0	@ top-most carry bit from addition
+
+	orr	$a1,$a1,$a2,lsl#31
+	mov	$a2,$a2,lsr#1
+	str	$a0,[$r_ptr,#0]
+	orr	$a2,$a2,$a3,lsl#31
+	mov	$a3,$a3,lsr#1
+	str	$a1,[$r_ptr,#4]
+	orr	$a3,$a3,$a4,lsl#31
+	mov	$a4,$a4,lsr#1
+	str	$a2,[$r_ptr,#8]
+	orr	$a4,$a4,$a5,lsl#31
+	mov	$a5,$a5,lsr#1
+	str	$a3,[$r_ptr,#12]
+	orr	$a5,$a5,$a6,lsl#31
+	mov	$a6,$a6,lsr#1
+	str	$a4,[$r_ptr,#16]
+	orr	$a6,$a6,$a7,lsl#31
+	mov	$a7,$a7,lsr#1
+	str	$a5,[$r_ptr,#20]
+	orr	$a7,$a7,$b_ptr,lsl#31	@ don't forget the top-most carry bit
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	_ecp_nistz256_div_by_2,.-_ecp_nistz256_div_by_2
+
+@ void	ecp_nistz256_sub(BN_ULONG r0[8],const BN_ULONG r1[8],
+@				       const BN_ULONG r2[8]);
+.globl	ecp_nistz256_sub
+.type	ecp_nistz256_sub,%function
+.align	4
+ecp_nistz256_sub:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_sub
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_sub,.-ecp_nistz256_sub
+
+.type	_ecp_nistz256_sub,%function
+.align	4
+_ecp_nistz256_sub:
+	str	lr,[sp,#-4]!		@ push lr
+
+	ldr	$a0,[$a_ptr,#0]
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	ldr	$a3,[$a_ptr,#12]
+	ldr	$a4,[$a_ptr,#16]
+	 ldr	$t0,[$b_ptr,#0]
+	ldr	$a5,[$a_ptr,#20]
+	 ldr	$t1,[$b_ptr,#4]
+	ldr	$a6,[$a_ptr,#24]
+	 ldr	$t2,[$b_ptr,#8]
+	ldr	$a7,[$a_ptr,#28]
+	 ldr	$t3,[$b_ptr,#12]
+	subs	$a0,$a0,$t0
+	 ldr	$t0,[$b_ptr,#16]
+	sbcs	$a1,$a1,$t1
+	 ldr	$t1,[$b_ptr,#20]
+	sbcs	$a2,$a2,$t2
+	 ldr	$t2,[$b_ptr,#24]
+	sbcs	$a3,$a3,$t3
+	 ldr	$t3,[$b_ptr,#28]
+	sbcs	$a4,$a4,$t0
+	sbcs	$a5,$a5,$t1
+	sbcs	$a6,$a6,$t2
+	sbcs	$a7,$a7,$t3
+	sbc	$ff,$ff,$ff		@ broadcast borrow bit
+	ldr	lr,[sp],#4		@ pop lr
+
+.Lreduce_by_add:
+
+	@ if a-b borrows, add modulus.
+	@
+	@ Note that because mod has special form, i.e. consists of
+	@ 0xffffffff, 1 and 0s, we can conditionally synthesize it by
+	@ broadcasting borrow bit to a register, $ff, and using it as
+	@ a whole or extracting single bit.
+
+	adds	$a0,$a0,$ff		@ add synthesized modulus
+	adcs	$a1,$a1,$ff
+	str	$a0,[$r_ptr,#0]
+	adcs	$a2,$a2,$ff
+	str	$a1,[$r_ptr,#4]
+	adcs	$a3,$a3,#0
+	str	$a2,[$r_ptr,#8]
+	adcs	$a4,$a4,#0
+	str	$a3,[$r_ptr,#12]
+	adcs	$a5,$a5,#0
+	str	$a4,[$r_ptr,#16]
+	adcs	$a6,$a6,$ff,lsr#31
+	str	$a5,[$r_ptr,#20]
+	adcs	$a7,$a7,$ff
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	_ecp_nistz256_sub,.-_ecp_nistz256_sub
+
+@ void	ecp_nistz256_neg(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_neg
+.type	ecp_nistz256_neg,%function
+.align	4
+ecp_nistz256_neg:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_neg
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_neg,.-ecp_nistz256_neg
+
+.type	_ecp_nistz256_neg,%function
+.align	4
+_ecp_nistz256_neg:
+	ldr	$a0,[$a_ptr,#0]
+	eor	$ff,$ff,$ff
+	ldr	$a1,[$a_ptr,#4]
+	ldr	$a2,[$a_ptr,#8]
+	subs	$a0,$ff,$a0
+	ldr	$a3,[$a_ptr,#12]
+	sbcs	$a1,$ff,$a1
+	ldr	$a4,[$a_ptr,#16]
+	sbcs	$a2,$ff,$a2
+	ldr	$a5,[$a_ptr,#20]
+	sbcs	$a3,$ff,$a3
+	ldr	$a6,[$a_ptr,#24]
+	sbcs	$a4,$ff,$a4
+	ldr	$a7,[$a_ptr,#28]
+	sbcs	$a5,$ff,$a5
+	sbcs	$a6,$ff,$a6
+	sbcs	$a7,$ff,$a7
+	sbc	$ff,$ff,$ff
+
+	b	.Lreduce_by_add
+.size	_ecp_nistz256_neg,.-_ecp_nistz256_neg
+___
+{
+my @acc=map("r$_",(3..11));
+my ($t0,$t1,$bj,$t2,$t3)=map("r$_",(0,1,2,12,14));
+
+$code.=<<___;
+@ void	ecp_nistz256_sqr_mont(BN_ULONG r0[8],const BN_ULONG r1[8]);
+.globl	ecp_nistz256_sqr_mont
+.type	ecp_nistz256_sqr_mont,%function
+.align	4
+ecp_nistz256_sqr_mont:
+	mov	$b_ptr,$a_ptr
+	b	.Lecp_nistz256_mul_mont
+.size	ecp_nistz256_sqr_mont,.-ecp_nistz256_sqr_mont
+
+@ void	ecp_nistz256_mul_mont(BN_ULONG r0[8],const BN_ULONG r1[8],
+@					     const BN_ULONG r2[8]);
+.globl	ecp_nistz256_mul_mont
+.type	ecp_nistz256_mul_mont,%function
+.align	4
+ecp_nistz256_mul_mont:
+.Lecp_nistz256_mul_mont:
+	stmdb	sp!,{r4-r12,lr}
+	bl	_ecp_nistz256_mul_mont
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_mul_mont,.-ecp_nistz256_mul_mont
+
+.type	_ecp_nistz256_mul_mont,%function
+.align	4
+_ecp_nistz256_mul_mont:
+	stmdb	sp!,{r0-r2,lr}			@ make a copy of arguments too
+
+	ldr	$bj,[$b_ptr,#0]			@ b[0]
+	ldmia	$a_ptr,{@acc[1]-@acc[8]}
+
+	umull	@acc[0],$t3,@acc[1],$bj		@ r[0]=a[0]*b[0]
+	stmdb	sp!,{$acc[1]-@acc[8]}		@ copy a[0-7] to stack, so
+						@ that it can be addressed
+						@ without spending register
+						@ on address
+	umull	@acc[1],$t0,@acc[2],$bj		@ r[1]=a[1]*b[0]
+	umull	@acc[2],$t1,@acc[3],$bj
+	adds	@acc[1],@acc[1],$t3		@ accumulate high part of mult
+	umull	@acc[3],$t2,@acc[4],$bj
+	adcs	@acc[2],@acc[2],$t0
+	umull	@acc[4],$t3,@acc[5],$bj
+	adcs	@acc[3],@acc[3],$t1
+	umull	@acc[5],$t0,@acc[6],$bj
+	adcs	@acc[4],@acc[4],$t2
+	umull	@acc[6],$t1,@acc[7],$bj
+	adcs	@acc[5],@acc[5],$t3
+	umull	@acc[7],$t2,@acc[8],$bj
+	adcs	@acc[6],@acc[6],$t0
+	adcs	@acc[7],@acc[7],$t1
+	eor	$t3,$t3,$t3			@ first overflow bit is zero
+	adc	@acc[8],$t2,#0
+___
+for(my $i=1;$i<8;$i++) {
+my $t4=@acc[0];
+
+	# Reduction iteration is normally performed by accumulating
+	# result of multiplication of modulus by "magic" digit [and
+	# omitting least significant word, which is guaranteed to
+	# be 0], but thanks to special form of modulus and "magic"
+	# digit being equal to least significant word, it can be
+	# performed with additions and subtractions alone. Indeed:
+	#
+	#        ffff.0001.0000.0000.0000.ffff.ffff.ffff
+	# *                                         abcd
+	# + xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.abcd
+	#
+	# Now observing that ff..ff*x = (2^n-1)*x = 2^n*x-x, we
+	# rewrite above as:
+	#
+	#   xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.abcd
+	# + abcd.0000.abcd.0000.0000.abcd.0000.0000.0000
+	# -      abcd.0000.0000.0000.0000.0000.0000.abcd
+	#
+	# or marking redundant operations:
+	#
+	#   xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.----
+	# + abcd.0000.abcd.0000.0000.abcd.----.----.----
+	# -      abcd.----.----.----.----.----.----.----
+
+$code.=<<___;
+	@ multiplication-less reduction $i
+	adds	@acc[3],@acc[3],@acc[0]		@ r[3]+=r[0]
+	 ldr	$bj,[sp,#40]			@ restore b_ptr
+	adcs	@acc[4],@acc[4],#0		@ r[4]+=0
+	adcs	@acc[5],@acc[5],#0		@ r[5]+=0
+	adcs	@acc[6],@acc[6],@acc[0]		@ r[6]+=r[0]
+	 ldr	$t1,[sp,#0]			@ load a[0]
+	adcs	@acc[7],@acc[7],#0		@ r[7]+=0
+	 ldr	$bj,[$bj,#4*$i]			@ load b[i]
+	adcs	@acc[8],@acc[8],@acc[0]		@ r[8]+=r[0]
+	 eor	$t0,$t0,$t0
+	adc	$t3,$t3,#0			@ overflow bit
+	subs	@acc[7],@acc[7],@acc[0]		@ r[7]-=r[0]
+	 ldr	$t2,[sp,#4]			@ a[1]
+	sbcs	@acc[8],@acc[8],#0		@ r[8]-=0
+	 umlal	@acc[1],$t0,$t1,$bj		@ "r[0]"+=a[0]*b[i]
+	 eor	$t1,$t1,$t1
+	sbc	@acc[0],$t3,#0			@ overflow bit, keep in mind
+						@ that netto result is
+						@ addition of a value which
+						@ makes underflow impossible
+
+	ldr	$t3,[sp,#8]			@ a[2]
+	umlal	@acc[2],$t1,$t2,$bj		@ "r[1]"+=a[1]*b[i]
+	 str	@acc[0],[sp,#36]		@ temporarily offload overflow
+	eor	$t2,$t2,$t2
+	ldr	$t4,[sp,#12]			@ a[3], $t4 is alias @acc[0]
+	umlal	@acc[3],$t2,$t3,$bj		@ "r[2]"+=a[2]*b[i]
+	eor	$t3,$t3,$t3
+	adds	@acc[2],@acc[2],$t0		@ accumulate high part of mult
+	ldr	$t0,[sp,#16]			@ a[4]
+	umlal	@acc[4],$t3,$t4,$bj		@ "r[3]"+=a[3]*b[i]
+	eor	$t4,$t4,$t4
+	adcs	@acc[3],@acc[3],$t1
+	ldr	$t1,[sp,#20]			@ a[5]
+	umlal	@acc[5],$t4,$t0,$bj		@ "r[4]"+=a[4]*b[i]
+	eor	$t0,$t0,$t0
+	adcs	@acc[4],@acc[4],$t2
+	ldr	$t2,[sp,#24]			@ a[6]
+	umlal	@acc[6],$t0,$t1,$bj		@ "r[5]"+=a[5]*b[i]
+	eor	$t1,$t1,$t1
+	adcs	@acc[5],@acc[5],$t3
+	ldr	$t3,[sp,#28]			@ a[7]
+	umlal	@acc[7],$t1,$t2,$bj		@ "r[6]"+=a[6]*b[i]
+	eor	$t2,$t2,$t2
+	adcs	@acc[6],@acc[6],$t4
+	 ldr	@acc[0],[sp,#36]		@ restore overflow bit
+	umlal	@acc[8],$t2,$t3,$bj		@ "r[7]"+=a[7]*b[i]
+	eor	$t3,$t3,$t3
+	adcs	@acc[7],@acc[7],$t0
+	adcs	@acc[8],@acc[8],$t1
+	adcs	@acc[0],$acc[0],$t2
+	adc	$t3,$t3,#0			@ new overflow bit
+___
+	push(@acc,shift(@acc));			# rotate registers, so that
+						# "r[i]" becomes r[i]
+}
+$code.=<<___;
+	@ last multiplication-less reduction
+	adds	@acc[3],@acc[3],@acc[0]
+	ldr	$r_ptr,[sp,#32]			@ restore r_ptr
+	adcs	@acc[4],@acc[4],#0
+	adcs	@acc[5],@acc[5],#0
+	adcs	@acc[6],@acc[6],@acc[0]
+	adcs	@acc[7],@acc[7],#0
+	adcs	@acc[8],@acc[8],@acc[0]
+	adc	$t3,$t3,#0
+	subs	@acc[7],@acc[7],@acc[0]
+	sbcs	@acc[8],@acc[8],#0
+	sbc	@acc[0],$t3,#0			@ overflow bit
+
+	@ Final step is "if result > mod, subtract mod", but we do it
+	@ "other way around", namely subtract modulus from result
+	@ and if it borrowed, add modulus back.
+
+	subs	@acc[1],@acc[1],#-1		@ compare to modulus
+	sbcs	@acc[2],@acc[2],#-1
+	sbcs	@acc[3],@acc[3],#-1
+	sbcs	@acc[4],@acc[4],#0
+	sbcs	@acc[5],@acc[5],#0
+	sbcs	@acc[6],@acc[6],#0
+	sbcs	@acc[7],@acc[7],#1
+	sbcs	@acc[8],@acc[8],#-1
+	ldr	lr,[sp,#44]			@ restore lr
+	sbc	@acc[0],@acc[0],#0		@ broadcast borrow bit
+	add	sp,sp,#48
+
+	@ Note that because mod has special form, i.e. consists of
+	@ 0xffffffff, 1 and 0s, we can conditionally synthesize it by
+	@ broadcasting borrow bit to a register, @acc[0], and using it as
+	@ a whole or extracting single bit.
+
+	adds	@acc[1],@acc[1],@acc[0]		@ add modulus or zero
+	adcs	@acc[2],@acc[2],@acc[0]
+	str	@acc[1],[$r_ptr,#0]
+	adcs	@acc[3],@acc[3],@acc[0]
+	str	@acc[2],[$r_ptr,#4]
+	adcs	@acc[4],@acc[4],#0
+	str	@acc[3],[$r_ptr,#8]
+	adcs	@acc[5],@acc[5],#0
+	str	@acc[4],[$r_ptr,#12]
+	adcs	@acc[6],@acc[6],#0
+	str	@acc[5],[$r_ptr,#16]
+	adcs	@acc[7],@acc[7],@acc[0],lsr#31
+	str	@acc[6],[$r_ptr,#20]
+	adc	@acc[8],@acc[8],@acc[0]
+	str	@acc[7],[$r_ptr,#24]
+	str	@acc[8],[$r_ptr,#28]
+
+	mov	pc,lr
+.size	_ecp_nistz256_mul_mont,.-_ecp_nistz256_mul_mont
+___
+}
+
+{
+my ($out,$inp,$index,$mask)=map("r$_",(0..3));
+$code.=<<___;
+@ void	ecp_nistz256_scatter_w5(void *r0,const P256_POINT *r1,
+@					 int r2);
+.globl	ecp_nistz256_scatter_w5
+.type	ecp_nistz256_scatter_w5,%function
+.align	5
+ecp_nistz256_scatter_w5:
+	stmdb	sp!,{r4-r11}
+
+	add	$out,$out,$index,lsl#2
+
+	ldmia	$inp!,{r4-r11}		@ X
+	str	r4,[$out,#64*0-4]
+	str	r5,[$out,#64*1-4]
+	str	r6,[$out,#64*2-4]
+	str	r7,[$out,#64*3-4]
+	str	r8,[$out,#64*4-4]
+	str	r9,[$out,#64*5-4]
+	str	r10,[$out,#64*6-4]
+	str	r11,[$out,#64*7-4]
+	add	$out,$out,#64*8
+
+	ldmia	$inp!,{r4-r11}		@ Y
+	str	r4,[$out,#64*0-4]
+	str	r5,[$out,#64*1-4]
+	str	r6,[$out,#64*2-4]
+	str	r7,[$out,#64*3-4]
+	str	r8,[$out,#64*4-4]
+	str	r9,[$out,#64*5-4]
+	str	r10,[$out,#64*6-4]
+	str	r11,[$out,#64*7-4]
+	add	$out,$out,#64*8
+
+	ldmia	$inp,{r4-r11}		@ Z
+	str	r4,[$out,#64*0-4]
+	str	r5,[$out,#64*1-4]
+	str	r6,[$out,#64*2-4]
+	str	r7,[$out,#64*3-4]
+	str	r8,[$out,#64*4-4]
+	str	r9,[$out,#64*5-4]
+	str	r10,[$out,#64*6-4]
+	str	r11,[$out,#64*7-4]
+
+	ldmia	sp!,{r4-r11}
+#if __ARM_ARCH__>=5 || defined(__thumb__)
+	bx	lr
+#else
+	mov	pc,lr
+#endif
+.size	ecp_nistz256_scatter_w5,.-ecp_nistz256_scatter_w5
+
+@ void	ecp_nistz256_gather_w5(P256_POINT *r0,const void *r1,
+@					      int r2);
+.globl	ecp_nistz256_gather_w5
+.type	ecp_nistz256_gather_w5,%function
+.align	5
+ecp_nistz256_gather_w5:
+	stmdb	sp!,{r4-r11}
+
+	cmp	$index,#0
+	mov	$mask,#0
+	subne	$index,$index,#1
+	movne	$mask,#-1
+	add	$inp,$inp,$index,lsl#2
+
+	ldr	r4,[$inp,#64*0]
+	ldr	r5,[$inp,#64*1]
+	ldr	r6,[$inp,#64*2]
+	and	r4,r4,$mask
+	ldr	r7,[$inp,#64*3]
+	and	r5,r5,$mask
+	ldr	r8,[$inp,#64*4]
+	and	r6,r6,$mask
+	ldr	r9,[$inp,#64*5]
+	and	r7,r7,$mask
+	ldr	r10,[$inp,#64*6]
+	and	r8,r8,$mask
+	ldr	r11,[$inp,#64*7]
+	add	$inp,$inp,#64*8
+	and	r9,r9,$mask
+	and	r10,r10,$mask
+	and	r11,r11,$mask
+	stmia	$out!,{r4-r11}	@ X
+
+	ldr	r4,[$inp,#64*0]
+	ldr	r5,[$inp,#64*1]
+	ldr	r6,[$inp,#64*2]
+	and	r4,r4,$mask
+	ldr	r7,[$inp,#64*3]
+	and	r5,r5,$mask
+	ldr	r8,[$inp,#64*4]
+	and	r6,r6,$mask
+	ldr	r9,[$inp,#64*5]
+	and	r7,r7,$mask
+	ldr	r10,[$inp,#64*6]
+	and	r8,r8,$mask
+	ldr	r11,[$inp,#64*7]
+	add	$inp,$inp,#64*8
+	and	r9,r9,$mask
+	and	r10,r10,$mask
+	and	r11,r11,$mask
+	stmia	$out!,{r4-r11}	@ Y
+
+	ldr	r4,[$inp,#64*0]
+	ldr	r5,[$inp,#64*1]
+	ldr	r6,[$inp,#64*2]
+	and	r4,r4,$mask
+	ldr	r7,[$inp,#64*3]
+	and	r5,r5,$mask
+	ldr	r8,[$inp,#64*4]
+	and	r6,r6,$mask
+	ldr	r9,[$inp,#64*5]
+	and	r7,r7,$mask
+	ldr	r10,[$inp,#64*6]
+	and	r8,r8,$mask
+	ldr	r11,[$inp,#64*7]
+	and	r9,r9,$mask
+	and	r10,r10,$mask
+	and	r11,r11,$mask
+	stmia	$out,{r4-r11}		@ Z
+
+	ldmia	sp!,{r4-r11}
+#if __ARM_ARCH__>=5 || defined(__thumb__)
+	bx	lr
+#else
+	mov	pc,lr
+#endif
+.size	ecp_nistz256_gather_w5,.-ecp_nistz256_gather_w5
+
+@ void	ecp_nistz256_scatter_w7(void *r0,const P256_POINT_AFFINE *r1,
+@					 int r2);
+.globl	ecp_nistz256_scatter_w7
+.type	ecp_nistz256_scatter_w7,%function
+.align	5
+ecp_nistz256_scatter_w7:
+	add	$out,$out,$index
+	mov	$index,#64/4
+.Loop_scatter_w7:
+	ldr	$mask,[$inp],#4
+	subs	$index,$index,#1
+	strb	$mask,[$out,#64*0-1]
+	mov	$mask,$mask,lsr#8
+	strb	$mask,[$out,#64*1-1]
+	mov	$mask,$mask,lsr#8
+	strb	$mask,[$out,#64*2-1]
+	mov	$mask,$mask,lsr#8
+	strb	$mask,[$out,#64*3-1]
+	add	$out,$out,#64*4
+	bne	.Loop_scatter_w7
+
+#if __ARM_ARCH__>=5 || defined(__thumb__)
+	bx	lr
+#else
+	mov	pc,lr
+#endif
+.size	ecp_nistz256_scatter_w7,.-ecp_nistz256_scatter_w7
+
+@ void	ecp_nistz256_gather_w7(P256_POINT_AFFINE *r0,const void *r1,
+@						     int r2);
+.globl	ecp_nistz256_gather_w7
+.type	ecp_nistz256_gather_w7,%function
+.align	5
+ecp_nistz256_gather_w7:
+	stmdb	sp!,{r4-r7}
+
+	cmp	$index,#0
+	mov	$mask,#0
+	subne	$index,$index,#1
+	movne	$mask,#-1
+	add	$inp,$inp,$index
+	mov	$index,#64/4
+	nop
+.Loop_gather_w7:
+	ldrb	r4,[$inp,#64*0]
+	subs	$index,$index,#1
+	ldrb	r5,[$inp,#64*1]
+	ldrb	r6,[$inp,#64*2]
+	ldrb	r7,[$inp,#64*3]
+	add	$inp,$inp,#64*4
+	orr	r4,r4,r5,lsl#8
+	orr	r4,r4,r6,lsl#16
+	orr	r4,r4,r7,lsl#24
+	and	r4,r4,$mask
+	str	r4,[$out],#4
+	bne	.Loop_gather_w7
+
+	ldmia	sp!,{r4-r7}
+#if __ARM_ARCH__>=5 || defined(__thumb__)
+	bx	lr
+#else
+	mov	pc,lr
+#endif
+.size	ecp_nistz256_gather_w7,.-ecp_nistz256_gather_w7
+___
+}
+if (0) {
+# In comparison to integer-only equivalent of below subroutine:
+#
+# Cortex-A8	+10%
+# Cortex-A9	-10%
+# Snapdragon S4	+5%
+#
+# As not all time is spent in multiplication, overall impact is deemed
+# too low to care about.
+
+my ($A0,$A1,$A2,$A3,$Bi,$zero,$temp)=map("d$_",(0..7));
+my $mask="q4";
+my $mult="q5";
+my @AxB=map("q$_",(8..15));
+
+my ($rptr,$aptr,$bptr,$toutptr)=map("r$_",(0..3));
+
+$code.=<<___;
+#if __ARM_ARCH__>=7
+.fpu	neon
+
+.globl	ecp_nistz256_mul_mont_neon
+.type	ecp_nistz256_mul_mont_neon,%function
+.align	5
+ecp_nistz256_mul_mont_neon:
+	mov	ip,sp
+	stmdb	sp!,{r4-r9}
+	vstmdb	sp!,{q4-q5}		@ ABI specification says so
+
+	sub		$toutptr,sp,#40
+	vld1.32		{${Bi}[0]},[$bptr,:32]!
+	veor		$zero,$zero,$zero
+	vld1.32		{$A0-$A3}, [$aptr]		@ can't specify :32 :-(
+	vzip.16		$Bi,$zero
+	mov		sp,$toutptr			@ alloca
+	vmov.i64	$mask,#0xffff
+
+	vmull.u32	@AxB[0],$Bi,${A0}[0]
+	vmull.u32	@AxB[1],$Bi,${A0}[1]
+	vmull.u32	@AxB[2],$Bi,${A1}[0]
+	vmull.u32	@AxB[3],$Bi,${A1}[1]
+	 vshr.u64	$temp,@AxB[0]#lo,#16
+	vmull.u32	@AxB[4],$Bi,${A2}[0]
+	 vadd.u64	@AxB[0]#hi,@AxB[0]#hi,$temp
+	vmull.u32	@AxB[5],$Bi,${A2}[1]
+	 vshr.u64	$temp,@AxB[0]#hi,#16		@ upper 32 bits of a[0]*b[0]
+	vmull.u32	@AxB[6],$Bi,${A3}[0]
+	 vand.u64	@AxB[0],@AxB[0],$mask		@ lower 32 bits of a[0]*b[0]
+	vmull.u32	@AxB[7],$Bi,${A3}[1]
+___
+for($i=1;$i<8;$i++) {
+$code.=<<___;
+	 vld1.32	{${Bi}[0]},[$bptr,:32]!
+	 veor		$zero,$zero,$zero
+	vadd.u64	@AxB[1]#lo,@AxB[1]#lo,$temp	@ reduction
+	vshl.u64	$mult,@AxB[0],#32
+	vadd.u64	@AxB[3],@AxB[3],@AxB[0]
+	vsub.u64	$mult,$mult,@AxB[0]
+	 vzip.16	$Bi,$zero
+	vadd.u64	@AxB[6],@AxB[6],@AxB[0]
+	vadd.u64	@AxB[7],@AxB[7],$mult
+___
+	push(@AxB,shift(@AxB));
+$code.=<<___;
+	vmlal.u32	@AxB[0],$Bi,${A0}[0]
+	vmlal.u32	@AxB[1],$Bi,${A0}[1]
+	vmlal.u32	@AxB[2],$Bi,${A1}[0]
+	vmlal.u32	@AxB[3],$Bi,${A1}[1]
+	 vshr.u64	$temp,@AxB[0]#lo,#16
+	vmlal.u32	@AxB[4],$Bi,${A2}[0]
+	 vadd.u64	@AxB[0]#hi,@AxB[0]#hi,$temp
+	vmlal.u32	@AxB[5],$Bi,${A2}[1]
+	 vshr.u64	$temp,@AxB[0]#hi,#16		@ upper 33 bits of a[0]*b[i]+t[0]
+	vmlal.u32	@AxB[6],$Bi,${A3}[0]
+	 vand.u64	@AxB[0],@AxB[0],$mask		@ lower 32 bits of a[0]*b[0]
+	vmull.u32	@AxB[7],$Bi,${A3}[1]
+___
+}
+$code.=<<___;
+	vadd.u64	@AxB[1]#lo,@AxB[1]#lo,$temp	@ last reduction
+	vshl.u64	$mult,@AxB[0],#32
+	vadd.u64	@AxB[3],@AxB[3],@AxB[0]
+	vsub.u64	$mult,$mult,@AxB[0]
+	vadd.u64	@AxB[6],@AxB[6],@AxB[0]
+	vadd.u64	@AxB[7],@AxB[7],$mult
+
+	vshr.u64	$temp,@AxB[1]#lo,#16		@ convert
+	vadd.u64	@AxB[1]#hi,@AxB[1]#hi,$temp
+	vshr.u64	$temp,@AxB[1]#hi,#16
+	vzip.16		@AxB[1]#lo,@AxB[1]#hi
+___
+foreach (2..7) {
+$code.=<<___;
+	vadd.u64	@AxB[$_]#lo,@AxB[$_]#lo,$temp
+	vst1.32		{@AxB[$_-1]#lo[0]},[$toutptr,:32]!
+	vshr.u64	$temp,@AxB[$_]#lo,#16
+	vadd.u64	@AxB[$_]#hi,@AxB[$_]#hi,$temp
+	vshr.u64	$temp,@AxB[$_]#hi,#16
+	vzip.16		@AxB[$_]#lo,@AxB[$_]#hi
+___
+}
+$code.=<<___;
+	vst1.32		{@AxB[7]#lo[0]},[$toutptr,:32]!
+	vst1.32		{$temp},[$toutptr]		@ upper 33 bits
+
+	ldr	r1,[sp,#0]
+	ldr	r2,[sp,#4]
+	ldr	r3,[sp,#8]
+	subs	r1,r1,#-1
+	ldr	r4,[sp,#12]
+	sbcs	r2,r2,#-1
+	ldr	r5,[sp,#16]
+	sbcs	r3,r3,#-1
+	ldr	r6,[sp,#20]
+	sbcs	r4,r4,#0
+	ldr	r7,[sp,#24]
+	sbcs	r5,r5,#0
+	ldr	r8,[sp,#28]
+	sbcs	r6,r6,#0
+	ldr	r9,[sp,#32]				@ top-most bit
+	sbcs	r7,r7,#1
+	sub	sp,ip,#40+16
+	sbcs	r8,r8,#-1
+	sbc	r9,r9,#0
+        vldmia  sp!,{q4-q5}
+
+	adds	r1,r1,r9
+	adcs	r2,r2,r9
+	str	r1,[$rptr,#0]
+	adcs	r3,r3,r9
+	str	r2,[$rptr,#4]
+	adcs	r4,r4,#0
+	str	r3,[$rptr,#8]
+	adcs	r5,r5,#0
+	str	r4,[$rptr,#12]
+	adcs	r6,r6,#0
+	str	r5,[$rptr,#16]
+	adcs	r7,r7,r9,lsr#31
+	str	r6,[$rptr,#20]
+	adcs	r8,r8,r9
+	str	r7,[$rptr,#24]
+	str	r8,[$rptr,#28]
+
+        ldmia   sp!,{r4-r9}
+	bx	lr
+.size	ecp_nistz256_mul_mont_neon,.-ecp_nistz256_mul_mont_neon
+#endif
+___
+}
+
+{{{
+########################################################################
+# Below $aN assignment matches order in which 256-bit result appears in
+# register bank at return from _ecp_nistz256_mul_mont, so that we can
+# skip over reloading it from memory. This means that below functions
+# use custom calling sequence accepting 256-bit input in registers,
+# output pointer in r0, $r_ptr, and optional pointer in r2, $b_ptr.
+#
+# See their "normal" counterparts for insights on calculations.
+
+my ($a0,$a1,$a2,$a3,$a4,$a5,$a6,$a7,
+    $t0,$t1,$t2,$t3)=map("r$_",(11,3..10,12,14,1));
+my $ff=$b_ptr;
+
+$code.=<<___;
+.type	__ecp_nistz256_sub_from,%function
+.align	5
+__ecp_nistz256_sub_from:
+	str	lr,[sp,#-4]!		@ push lr
+
+	 ldr	$t0,[$b_ptr,#0]
+	 ldr	$t1,[$b_ptr,#4]
+	 ldr	$t2,[$b_ptr,#8]
+	 ldr	$t3,[$b_ptr,#12]
+	subs	$a0,$a0,$t0
+	 ldr	$t0,[$b_ptr,#16]
+	sbcs	$a1,$a1,$t1
+	 ldr	$t1,[$b_ptr,#20]
+	sbcs	$a2,$a2,$t2
+	 ldr	$t2,[$b_ptr,#24]
+	sbcs	$a3,$a3,$t3
+	 ldr	$t3,[$b_ptr,#28]
+	sbcs	$a4,$a4,$t0
+	sbcs	$a5,$a5,$t1
+	sbcs	$a6,$a6,$t2
+	sbcs	$a7,$a7,$t3
+	sbc	$ff,$ff,$ff		@ broadcast borrow bit
+	ldr	lr,[sp],#4		@ pop lr
+
+	adds	$a0,$a0,$ff		@ add synthesized modulus
+	adcs	$a1,$a1,$ff
+	str	$a0,[$r_ptr,#0]
+	adcs	$a2,$a2,$ff
+	str	$a1,[$r_ptr,#4]
+	adcs	$a3,$a3,#0
+	str	$a2,[$r_ptr,#8]
+	adcs	$a4,$a4,#0
+	str	$a3,[$r_ptr,#12]
+	adcs	$a5,$a5,#0
+	str	$a4,[$r_ptr,#16]
+	adcs	$a6,$a6,$ff,lsr#31
+	str	$a5,[$r_ptr,#20]
+	adcs	$a7,$a7,$ff
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	__ecp_nistz256_sub_from,.-__ecp_nistz256_sub_from
+
+.type	__ecp_nistz256_sub_morf,%function
+.align	5
+__ecp_nistz256_sub_morf:
+	str	lr,[sp,#-4]!		@ push lr
+
+	 ldr	$t0,[$b_ptr,#0]
+	 ldr	$t1,[$b_ptr,#4]
+	 ldr	$t2,[$b_ptr,#8]
+	 ldr	$t3,[$b_ptr,#12]
+	subs	$a0,$t0,$a0
+	 ldr	$t0,[$b_ptr,#16]
+	sbcs	$a1,$t1,$a1
+	 ldr	$t1,[$b_ptr,#20]
+	sbcs	$a2,$t2,$a2
+	 ldr	$t2,[$b_ptr,#24]
+	sbcs	$a3,$t3,$a3
+	 ldr	$t3,[$b_ptr,#28]
+	sbcs	$a4,$t0,$a4
+	sbcs	$a5,$t1,$a5
+	sbcs	$a6,$t2,$a6
+	sbcs	$a7,$t3,$a7
+	sbc	$ff,$ff,$ff		@ broadcast borrow bit
+	ldr	lr,[sp],#4		@ pop lr
+
+	adds	$a0,$a0,$ff		@ add synthesized modulus
+	adcs	$a1,$a1,$ff
+	str	$a0,[$r_ptr,#0]
+	adcs	$a2,$a2,$ff
+	str	$a1,[$r_ptr,#4]
+	adcs	$a3,$a3,#0
+	str	$a2,[$r_ptr,#8]
+	adcs	$a4,$a4,#0
+	str	$a3,[$r_ptr,#12]
+	adcs	$a5,$a5,#0
+	str	$a4,[$r_ptr,#16]
+	adcs	$a6,$a6,$ff,lsr#31
+	str	$a5,[$r_ptr,#20]
+	adcs	$a7,$a7,$ff
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	__ecp_nistz256_sub_morf,.-__ecp_nistz256_sub_morf
+
+.type	__ecp_nistz256_mul_by_2,%function
+.align	4
+__ecp_nistz256_mul_by_2:
+	adds	$a0,$a0,$a0		@ a[0:7]+=a[0:7]
+	adcs	$a1,$a1,$a1
+	adcs	$a2,$a2,$a2
+	adcs	$a3,$a3,$a3
+	adcs	$a4,$a4,$a4
+	adcs	$a5,$a5,$a5
+	adcs	$a6,$a6,$a6
+	mov	$ff,#0
+	adcs	$a7,$a7,$a7
+	movcs	$ff,#-1			@ $ff = carry ? -1 : 0
+
+	subs	$a0,$a0,$ff		@ subtract synthesized modulus
+	sbcs	$a1,$a1,$ff
+	str	$a0,[$r_ptr,#0]
+	sbcs	$a2,$a2,$ff
+	str	$a1,[$r_ptr,#4]
+	sbcs	$a3,$a3,#0
+	str	$a2,[$r_ptr,#8]
+	sbcs	$a4,$a4,#0
+	str	$a3,[$r_ptr,#12]
+	sbcs	$a5,$a5,#0
+	str	$a4,[$r_ptr,#16]
+	sbcs	$a6,$a6,$ff,lsr#31
+	str	$a5,[$r_ptr,#20]
+	sbcs	$a7,$a7,$ff
+	str	$a6,[$r_ptr,#24]
+	str	$a7,[$r_ptr,#28]
+
+	mov	pc,lr
+.size	__ecp_nistz256_mul_by_2,.-__ecp_nistz256_mul_by_2
+
+___
+
+########################################################################
+# following subroutines are "literal" implemetation of those found in
+# ecp_nistz256.c
+#
+########################################################################
+# void ecp_nistz256_point_double(P256_POINT *out,const P256_POINT *inp);
+#
+{
+my ($S,$M,$Zsqr,$in_x,$tmp0)=map(32*$_,(0..4));
+# above map() describes stack layout with 5 temporary
+# 256-bit vectors on top. Then note that we push
+# starting from r0, which means that we have copy of
+# input arguments just below these temporary vectors.
+
+$code.=<<___;
+.globl	ecp_nistz256_point_double
+.type	ecp_nistz256_point_double,%function
+.align	5
+ecp_nistz256_point_double:
+	stmdb	sp!,{r0-r12,lr}		@ push from r0, unusual, but intentional
+	sub	sp,sp,#32*5
+
+	add	r3,sp,#$in_x
+	ldmia	$a_ptr!,{r4-r11}	@ copy in_x
+	stmia	r3,{r4-r11}
+
+	add	$r_ptr,sp,#$S
+	bl	_ecp_nistz256_mul_by_2	@ p256_mul_by_2(S, in_y);
+
+	add	$b_ptr,$a_ptr,#32
+	add	$a_ptr,$a_ptr,#32
+	add	$r_ptr,sp,#$Zsqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Zsqr, in_z);
+
+	add	$a_ptr,sp,#$S
+	add	$b_ptr,sp,#$S
+	add	$r_ptr,sp,#$S
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(S, S);
+
+	ldr	$b_ptr,[sp,#32*5+4]
+	add	$a_ptr,$b_ptr,#32
+	add	$b_ptr,$b_ptr,#64
+	add	$r_ptr,sp,#$tmp0
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(tmp0, in_z, in_y);
+
+	ldr	$r_ptr,[sp,#32*5]
+	add	$r_ptr,$r_ptr,#64
+	bl	__ecp_nistz256_mul_by_2	@ p256_mul_by_2(res_z, tmp0);
+
+	add	$a_ptr,sp,#$in_x
+	add	$b_ptr,sp,#$Zsqr
+	add	$r_ptr,sp,#$M
+	bl	_ecp_nistz256_add	@ p256_add(M, in_x, Zsqr);
+
+	add	$a_ptr,sp,#$in_x
+	add	$b_ptr,sp,#$Zsqr
+	add	$r_ptr,sp,#$Zsqr
+	bl	_ecp_nistz256_sub	@ p256_sub(Zsqr, in_x, Zsqr);
+
+	add	$a_ptr,sp,#$S
+	add	$b_ptr,sp,#$S
+	add	$r_ptr,sp,#$tmp0
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(tmp0, S);
+
+	add	$a_ptr,sp,#$Zsqr
+	add	$b_ptr,sp,#$M
+	add	$r_ptr,sp,#$M
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(M, M, Zsqr);
+
+	ldr	$r_ptr,[sp,#32*5]
+	add	$a_ptr,sp,#$tmp0
+	add	$r_ptr,$r_ptr,#32
+	bl	_ecp_nistz256_div_by_2	@ p256_div_by_2(res_y, tmp0);
+
+	add	$a_ptr,sp,#$M
+	add	$r_ptr,sp,#$M
+	bl	_ecp_nistz256_mul_by_3	@ p256_mul_by_3(M, M);
+
+	add	$a_ptr,sp,#$in_x
+	add	$b_ptr,sp,#$S
+	add	$r_ptr,sp,#$S
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S, S, in_x);
+
+	add	$r_ptr,sp,#$tmp0
+	bl	__ecp_nistz256_mul_by_2	@ p256_mul_by_2(tmp0, S);
+
+	ldr	$r_ptr,[sp,#32*5]
+	add	$a_ptr,sp,#$M
+	add	$b_ptr,sp,#$M
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(res_x, M);
+
+	add	$b_ptr,sp,#$tmp0
+	bl	__ecp_nistz256_sub_from	@ p256_sub(res_x, res_x, tmp0);
+
+	add	$b_ptr,sp,#$S
+	add	$r_ptr,sp,#$S
+	bl	__ecp_nistz256_sub_morf	@ p256_sub(S, S, res_x);
+
+	add	$a_ptr,sp,#$M
+	add	$b_ptr,sp,#$S
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S, S, M);
+
+	ldr	$r_ptr,[sp,#32*5]
+	add	$b_ptr,$r_ptr,#32
+	add	$r_ptr,$r_ptr,#32
+	bl	__ecp_nistz256_sub_from	@ p256_sub(res_y, S, res_y);
+
+	add	sp,sp,#32*5+16		@ +16 means "skip even over saved r0-r3"
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.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,
+    $in1_x,$in1_y,$in1_z,
+    $in2_x,$in2_y,$in2_z,
+    $H,$Hsqr,$R,$Rsqr,$Hcub,
+    $U1,$U2,$S1,$S2)=map(32*$_,(0..17));
+my ($Z1sqr, $Z2sqr) = ($Hsqr, $Rsqr);
+# above map() describes stack layout with 18 temporary
+# 256-bit vectors on top. Then note that we push
+# starting from r0, which means that we have copy of
+# input arguments just below these temporary vectors.
+# We use three of them for !in1infty, !in2intfy and
+# result of check for zero.
+
+$code.=<<___;
+.globl	ecp_nistz256_point_add
+.type	ecp_nistz256_point_add,%function
+.align	5
+ecp_nistz256_point_add:
+	stmdb	sp!,{r0-r12,lr}		@ push from r0, unusual, but intentional
+	sub	sp,sp,#32*18
+
+	ldmia	$b_ptr!,{r4-r11}	@ copy in2
+	add	r3,sp,#$in2_x
+	orr	r12,r4,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$b_ptr!,{r4-r11}
+	orr	r12,r12,r4
+	orr	r12,r12,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$b_ptr,{r4-r11}
+	cmp	r12,#0
+	movne	r12,#-1
+	stmia	r3,{r4-r11}
+	str	r12,[sp,#32*18+8]	@ !in2infty
+
+	ldmia	$a_ptr!,{r4-r11}	@ copy in1
+	add	r3,sp,#$in1_x
+	orr	r12,r4,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$a_ptr!,{r4-r11}
+	orr	r12,r12,r4
+	orr	r12,r12,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$a_ptr,{r4-r11}
+	cmp	r12,#0
+	movne	r12,#-1
+	stmia	r3,{r4-r11}
+	str	r12,[sp,#32*18+4]	@ !in1infty
+
+	add	$a_ptr,sp,#$in2_z
+	add	$b_ptr,sp,#$in2_z
+	add	$r_ptr,sp,#$Z2sqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Z2sqr, in2_z);
+
+	add	$a_ptr,sp,#$in1_z
+	add	$b_ptr,sp,#$in1_z
+	add	$r_ptr,sp,#$Z1sqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Z1sqr, in1_z);
+
+	add	$a_ptr,sp,#$in2_z
+	add	$b_ptr,sp,#$Z2sqr
+	add	$r_ptr,sp,#$S1
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S1, Z2sqr, in2_z);
+
+	add	$a_ptr,sp,#$in1_z
+	add	$b_ptr,sp,#$Z1sqr
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, Z1sqr, in1_z);
+
+	add	$a_ptr,sp,#$in1_y
+	add	$b_ptr,sp,#$S1
+	add	$r_ptr,sp,#$S1
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S1, S1, in1_y);
+
+	add	$a_ptr,sp,#$in2_y
+	add	$b_ptr,sp,#$S2
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, S2, in2_y);
+
+	add	$b_ptr,sp,#$S1
+	add	$r_ptr,sp,#$R
+	bl	__ecp_nistz256_sub_from	@ p256_sub(R, S2, S1);
+
+	orr	$a0,$a0,$a1		@ see if result is zero
+	orr	$a2,$a2,$a3
+	orr	$a4,$a4,$a5
+	orr	$a0,$a0,$a2
+	orr	$a4,$a4,$a6
+	orr	$a0,$a0,$a7
+	 add	$a_ptr,sp,#$in1_x
+	orr	$a0,$a0,$a4
+	 add	$b_ptr,sp,#$Z2sqr
+	str	$a0,[sp,#32*18+12]
+
+	add	$r_ptr,sp,#$U1
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(U1, in1_x, Z2sqr);
+
+	add	$a_ptr,sp,#$in2_x
+	add	$b_ptr,sp,#$Z1sqr
+	add	$r_ptr,sp,#$U2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(U2, in2_x, Z1sqr);
+
+	add	$b_ptr,sp,#$U1
+	add	$r_ptr,sp,#$H
+	bl	__ecp_nistz256_sub_from	@ p256_sub(H, U2, U1);
+
+	orr	$a0,$a0,$a1		@ see if result is zero
+	orr	$a2,$a2,$a3
+	orr	$a4,$a4,$a5
+	orr	$a0,$a0,$a2
+	orr	$a4,$a4,$a6
+	orr	$a0,$a0,$a7
+	orrs	$a0,$a0,$a4
+
+	bne	.Ladd_proceed		@ is_equal(U1,U2)?
+
+	ldr	$t0,[sp,#32*18+4]
+	ldr	$t1,[sp,#32*18+8]
+	ldr	$t2,[sp,#32*18+12]
+	tst	$t0,$t1
+	beq	.Ladd_proceed		@ (in1infty || in2infty)?
+	tst	$t2,$t2
+	beq	.Ladd_proceed		@ is_equal(S1,S2)?
+
+	ldr	$r_ptr,[sp,#32*18]
+	eor	r4,r4,r4
+	eor	r5,r5,r5
+	eor	r6,r6,r6
+	eor	r7,r7,r7
+	eor	r8,r8,r8
+	eor	r9,r9,r9
+	eor	r10,r10,r10
+	eor	r11,r11,r11
+	stmia	$r_ptr!,{r4-r11}
+	stmia	$r_ptr!,{r4-r11}
+	stmia	$r_ptr!,{r4-r11}
+	b	.Ladd_done
+
+.align	4
+.Ladd_proceed:
+	add	$a_ptr,sp,#$R
+	add	$b_ptr,sp,#$R
+	add	$r_ptr,sp,#$Rsqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Rsqr, R);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$in1_z
+	add	$r_ptr,sp,#$res_z
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(res_z, H, in1_z);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$H
+	add	$r_ptr,sp,#$Hsqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Hsqr, H);
+
+	add	$a_ptr,sp,#$in2_z
+	add	$b_ptr,sp,#$res_z
+	add	$r_ptr,sp,#$res_z
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(res_z, res_z, in2_z);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$Hsqr
+	add	$r_ptr,sp,#$Hcub
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(Hcub, Hsqr, H);
+
+	add	$a_ptr,sp,#$Hsqr
+	add	$b_ptr,sp,#$U1
+	add	$r_ptr,sp,#$U2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(U2, U1, Hsqr);
+
+	add	$r_ptr,sp,#$Hsqr
+	bl	__ecp_nistz256_mul_by_2	@ p256_mul_by_2(Hsqr, U2);
+
+	add	$b_ptr,sp,#$Rsqr
+	add	$r_ptr,sp,#$res_x
+	bl	__ecp_nistz256_sub_morf	@ p256_sub(res_x, Rsqr, Hsqr);
+
+	add	$b_ptr,sp,#$Hcub
+	bl	__ecp_nistz256_sub_from	@  p256_sub(res_x, res_x, Hcub);
+
+	add	$b_ptr,sp,#$U2
+	add	$r_ptr,sp,#$res_y
+	bl	__ecp_nistz256_sub_morf	@ p256_sub(res_y, U2, res_x);
+
+	add	$a_ptr,sp,#$Hcub
+	add	$b_ptr,sp,#$S1
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, S1, Hcub);
+
+	add	$a_ptr,sp,#$R
+	add	$b_ptr,sp,#$res_y
+	add	$r_ptr,sp,#$res_y
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(res_y, res_y, R);
+
+	add	$b_ptr,sp,#$S2
+	bl	__ecp_nistz256_sub_from	@ p256_sub(res_y, res_y, S2);
+
+	ldr	r11,[sp,#32*18+4]	@ !in1intfy
+	ldr	r12,[sp,#32*18+8]	@ !in2intfy
+	add	r1,sp,#$res_x
+	add	r2,sp,#$in2_x
+	and	r10,r11,r12
+	mvn	r11,r11
+	add	r3,sp,#$in1_x
+	and	r11,r11,r12
+	mvn	r12,r12
+	ldr	$r_ptr,[sp,#32*18]
+___
+for($i=0;$i<96;$i+=8) {			# conditional moves
+$code.=<<___;
+	ldmia	r1!,{r4-r5}		@ res_x
+	ldmia	r2!,{r6-r7}		@ in2_x
+	ldmia	r3!,{r8-r9}		@ in1_x
+	and	r4,r4,r10
+	and	r5,r5,r10
+	and	r6,r6,r11
+	and	r7,r7,r11
+	and	r8,r8,r12
+	and	r9,r9,r12
+	orr	r4,r4,r6
+	orr	r5,r5,r7
+	orr	r4,r4,r8
+	orr	r5,r5,r9
+	stmia	$r_ptr!,{r4-r5}
+___
+}
+$code.=<<___;
+.Ladd_done:
+	add	sp,sp,#32*18+16		@ +16 means "skip even over saved r0-r3"
+#if __ARM_ARCH__>=5 || defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.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,
+    $in1_x,$in1_y,$in1_z,
+    $in2_x,$in2_y,
+    $U2,$S2,$H,$R,$Hsqr,$Hcub,$Rsqr)=map(32*$_,(0..14));
+my $Z1sqr = $S2;
+# above map() describes stack layout with 18 temporary
+# 256-bit vectors on top. Then note that we push
+# starting from r0, which means that we have copy of
+# input arguments just below these temporary vectors.
+# We use two of them for !in1infty, !in2intfy.
+
+my @ONE_mont=(1,0,0,-1,-1,-1,-2,0);
+
+$code.=<<___;
+.globl	ecp_nistz256_point_add_affine
+.type	ecp_nistz256_point_add_affine,%function
+.align	5
+ecp_nistz256_point_add_affine:
+	stmdb	sp!,{r0-r12,lr}		@ push from r0, unusual, but intentional
+	sub	sp,sp,#32*15
+
+	ldmia	$a_ptr!,{r4-r11}	@ copy in1
+	add	r3,sp,#$in1_x
+	orr	r12,r4,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$a_ptr!,{r4-r11}
+	orr	r12,r12,r4
+	orr	r12,r12,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$a_ptr,{r4-r11}
+	cmp	r12,#0
+	movne	r12,#-1
+	stmia	r3,{r4-r11}
+	str	r12,[sp,#32*15+4]	@ !in1infty
+
+	ldmia	$b_ptr!,{r4-r11}	@ copy in2
+	add	r3,sp,#$in2_x
+	orr	r12,r4,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	ldmia	$b_ptr!,{r4-r11}
+	orr	r12,r12,r4
+	orr	r12,r12,r5
+	orr	r12,r12,r6
+	orr	r12,r12,r7
+	orr	r12,r12,r8
+	orr	r12,r12,r9
+	orr	r12,r12,r10
+	orr	r12,r12,r11
+	stmia	r3!,{r4-r11}
+	cmp	r12,#0
+	movne	r12,#-1
+	str	r12,[sp,#32*15+8]	@ !in2infty
+
+	add	$a_ptr,sp,#$in1_z
+	add	$b_ptr,sp,#$in1_z
+	add	$r_ptr,sp,#$Z1sqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Z1sqr, in1_z);
+
+	add	$a_ptr,sp,#$Z1sqr
+	add	$b_ptr,sp,#$in2_x
+	add	$r_ptr,sp,#$U2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(U2, Z1sqr, in2_x);
+
+	add	$b_ptr,sp,#$in1_x
+	add	$r_ptr,sp,#$H
+	bl	__ecp_nistz256_sub_from	@ p256_sub(H, U2, in1_x);
+
+	add	$a_ptr,sp,#$Z1sqr
+	add	$b_ptr,sp,#$in1_z
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, Z1sqr, in1_z);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$in1_z
+	add	$r_ptr,sp,#$res_z
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(res_z, H, in1_z);
+
+	add	$a_ptr,sp,#$in2_y
+	add	$b_ptr,sp,#$S2
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, S2, in2_y);
+
+	add	$b_ptr,sp,#$in1_y
+	add	$r_ptr,sp,#$R
+	bl	__ecp_nistz256_sub_from	@ p256_sub(R, S2, in1_y);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$H
+	add	$r_ptr,sp,#$Hsqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Hsqr, H);
+
+	add	$a_ptr,sp,#$R
+	add	$b_ptr,sp,#$R
+	add	$r_ptr,sp,#$Rsqr
+	bl	_ecp_nistz256_mul_mont	@ p256_sqr_mont(Rsqr, R);
+
+	add	$a_ptr,sp,#$H
+	add	$b_ptr,sp,#$Hsqr
+	add	$r_ptr,sp,#$Hcub
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(Hcub, Hsqr, H);
+
+	add	$a_ptr,sp,#$Hsqr
+	add	$b_ptr,sp,#$in1_x
+	add	$r_ptr,sp,#$U2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(U2, in1_x, Hsqr);
+
+	add	$r_ptr,sp,#$Hsqr
+	bl	__ecp_nistz256_mul_by_2	@ p256_mul_by_2(Hsqr, U2);
+
+	add	$b_ptr,sp,#$Rsqr
+	add	$r_ptr,sp,#$res_x
+	bl	__ecp_nistz256_sub_morf	@ p256_sub(res_x, Rsqr, Hsqr);
+
+	add	$b_ptr,sp,#$Hcub
+	bl	__ecp_nistz256_sub_from	@  p256_sub(res_x, res_x, Hcub);
+
+	add	$b_ptr,sp,#$U2
+	add	$r_ptr,sp,#$res_y
+	bl	__ecp_nistz256_sub_morf	@ p256_sub(res_y, U2, res_x);
+
+	add	$a_ptr,sp,#$Hcub
+	add	$b_ptr,sp,#$in1_y
+	add	$r_ptr,sp,#$S2
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(S2, in1_y, Hcub);
+
+	add	$a_ptr,sp,#$R
+	add	$b_ptr,sp,#$res_y
+	add	$r_ptr,sp,#$res_y
+	bl	_ecp_nistz256_mul_mont	@ p256_mul_mont(res_y, res_y, R);
+
+	add	$b_ptr,sp,#$S2
+	bl	__ecp_nistz256_sub_from	@ p256_sub(res_y, res_y, S2);
+
+	ldr	r11,[sp,#32*15+4]	@ !in1intfy
+	ldr	r12,[sp,#32*15+8]	@ !in2intfy
+	add	r1,sp,#$res_x
+	add	r2,sp,#$in2_x
+	and	r10,r11,r12
+	mvn	r11,r11
+	add	r3,sp,#$in1_x
+	and	r11,r11,r12
+	mvn	r12,r12
+	ldr	$r_ptr,[sp,#32*15]
+___
+for($i=0;$i<64;$i+=8) {			# conditional moves
+$code.=<<___;
+	ldmia	r1!,{r4-r5}		@ res_x
+	ldmia	r2!,{r6-r7}		@ in2_x
+	ldmia	r3!,{r8-r9}		@ in1_x
+	and	r4,r4,r10
+	and	r5,r5,r10
+	and	r6,r6,r11
+	and	r7,r7,r11
+	and	r8,r8,r12
+	and	r9,r9,r12
+	orr	r4,r4,r6
+	orr	r5,r5,r7
+	orr	r4,r4,r8
+	orr	r5,r5,r9
+	stmia	$r_ptr!,{r4-r5}
+___
+}
+for(;$i<96;$i+=8) {
+my $j=($i-64)/4;
+$code.=<<___;
+	ldmia	r1!,{r4-r5}		@ res_z
+	ldmia	r3!,{r8-r9}		@ in1_z
+	and	r4,r4,r10
+	and	r5,r5,r10
+	and	r6,r11,#@ONE_mont[$j]
+	and	r7,r11,#@ONE_mont[$j+1]
+	and	r8,r8,r12
+	and	r9,r9,r12
+	orr	r4,r4,r6
+	orr	r5,r5,r7
+	orr	r4,r4,r8
+	orr	r5,r5,r9
+	stmia	$r_ptr!,{r4-r5}
+___
+}
+$code.=<<___;
+	add	sp,sp,#32*15+16		@ +16 means "skip even over saved r0-r3"
+#if __ARM_ARCH__>=5 || !defined(__thumb__)
+	ldmia	sp!,{r4-r12,pc}
+#else
+	ldmia	sp!,{r4-r12,lr}
+	bx	lr			@ interoperable with Thumb ISA:-)
+#endif
+.size	ecp_nistz256_point_add_affine,.-ecp_nistz256_point_add_affine
+___
+}					}}}
+
+foreach (split("\n",$code)) {
+	s/\`([^\`]*)\`/eval $1/geo;
+
+	s/\bq([0-9]+)#(lo|hi)/sprintf "d%d",2*$1+($2 eq "hi")/geo;
+
+	print $_,"\n";
+}
+close STDOUT;	# enforce flush
-- 
2.25.1