Montgomery multiplication for MIPS III/IV. Not engaged.

#!/usr/bin/env perl

#

# ====================================================================

# Written by Andy Polyakov <appro@fy.chalmers.se> 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/.

# ====================================================================

# This module doesn't present direct interest for OpenSSL, because it

# doesn't provide better performance for longer keys. While 512-bit

# RSA private key operations are 40% faster, 1024-bit ones are hardly

# faster at all, while longer key operations are slower by up to 20%.

# It might be of interest to embedded system developers though, as

# it's smaller than 1KB, yet offers ~3x improvement over compiler

# generated code.

#

# The module targets N32 and N64 MIPS ABIs and currently is a bit

# IRIX-centric, i.e. is likely to require adaptation for other OSes.

# int bn_mul_mont(

$rp="a0";	# BN_ULONG *rp,

$ap="a1";	# const BN_ULONG *ap,

$bp="a2";	# const BN_ULONG *bp,

$np="a3";	# const BN_ULONG *np,

$n0="a4";	# const BN_ULONG *n0,

$num="a5";	# int num);

$lo0="a6";

$hi0="a7";

$lo1="v0";

$hi1="v1";

$aj="t0";

$bi="t1";

$nj="t2";

$tp="t3";

$alo="s0";

$ahi="s1";

$nlo="s2";

$nhi="s3";

$tj="s4";

$i="s5";

$j="s6";

$fp="t8";

$m1="t9";

$FRAME=8*(2+8);

$code=<<___;

#include <asm.h>

#include <regdef.h>

.text

.set	noat

.set	reorder

.align	5

.globl	bn_mul_mont

.ent	bn_mul_mont

bn_mul_mont:

	.set	noreorder

	PTR_SUB	sp,64

	move	$fp,sp

	.frame	$fp,64,ra

	slt	AT,$num,4

	li	v0,0

	beqzl	AT,.Lproceed

	nop

	jr	ra

	PTR_ADD	sp,$fp,64

	.set	reorder

.align	5

.Lproceed:

	ld	$n0,0($n0)

	ld	$bi,0($bp)	# bp[0]

	ld	$aj,0($ap)	# ap[0]

	ld	$nj,0($np)	# np[0]

	PTR_SUB	sp,16		# place for two extra words

	sll	$num,3

	li	AT,-4096

	PTR_SUB	sp,$num

	and	sp,AT

	sd	s0,0($fp)

	sd	s1,8($fp)

	sd	s2,16($fp)

	sd	s3,24($fp)

	sd	s4,32($fp)

	sd	s5,40($fp)

	sd	s6,48($fp)

	sd	s7,56($fp)

	dmultu	$aj,$bi

	ld	$alo,8($ap)

	ld	$nlo,8($np)

	mflo	$lo0

	mfhi	$hi0

	dmultu	$lo0,$n0

	mflo	$m1

	dmultu	$alo,$bi

	mflo	$alo

	mfhi	$ahi

	dmultu	$nj,$m1

	mflo	$lo1

	mfhi	$hi1

	dmultu	$nlo,$m1

	daddu	$lo1,$lo0

	sltu	AT,$lo1,$lo0

	daddu	$hi1,AT

	mflo	$nlo

	mfhi	$nhi

	move	$tp,sp

	li	$j,16

.align	4

.L1st:

	.set	noreorder

	PTR_ADD	$aj,$ap,$j

	ld	$aj,($aj)

	PTR_ADD	$nj,$np,$j

	ld	$nj,($nj)

	dmultu	$aj,$bi

	daddu	$lo0,$alo,$hi0

	daddu	$lo1,$nlo,$hi1

	sltu	AT,$lo0,$hi0

	sltu	s7,$lo1,$hi1

	daddu	$hi0,$ahi,AT

	daddu	$hi1,$nhi,s7

	mflo	$alo

	mfhi	$ahi

	daddu	$lo1,$lo0

	sltu	AT,$lo1,$lo0

	dmultu	$nj,$m1

	daddu	$hi1,AT

	addu	$j,8

	sd	$lo1,($tp)

	sltu	s7,$j,$num

	mflo	$nlo

	mfhi	$nhi

	bnez	s7,.L1st

	PTR_ADD	$tp,8

	.set	reorder

	daddu	$lo0,$alo,$hi0

	sltu	AT,$lo0,$hi0

	daddu	$hi0,$ahi,AT

	daddu	$lo1,$nlo,$hi1

	sltu	s7,$lo1,$hi1

	daddu	$hi1,$nhi,s7

	daddu	$lo1,$lo0

	sltu	AT,$lo1,$lo0

	daddu	$hi1,AT

	sd	$lo1,($tp)

	daddu	$hi1,$hi0

	sltu	AT,$hi1,$hi0

	sd	$hi1,8($tp)

	sd	AT,16($tp)

	li	$i,8

.align	4

.Louter:

	PTR_ADD	$bi,$bp,$i

	ld	$bi,($bi)

	ld	$aj,($ap)

	ld	$alo,8($ap)

	ld	$tj,(sp)

	dmultu	$aj,$bi

	ld	$nj,($np)

	ld	$nlo,8($np)

	mflo	$lo0

	mfhi	$hi0

	daddu	$lo0,$tj

	dmultu	$lo0,$n0

	sltu	AT,$lo0,$tj

	daddu	$hi0,AT

	mflo	$m1

	dmultu	$alo,$bi

	mflo	$alo

	mfhi	$ahi

	dmultu	$nj,$m1

	mflo	$lo1

	mfhi	$hi1

	dmultu	$nlo,$m1

	daddu	$lo1,$lo0

	sltu	AT,$lo1,$lo0

	daddu	$hi1,AT

	mflo	$nlo

	mfhi	$nhi

	move	$tp,sp

	li	$j,16

	ld	$tj,8($tp)

.align	4

.Linner:

	.set	noreorder

	PTR_ADD	$aj,$ap,$j

	ld	$aj,($aj)

	PTR_ADD	$nj,$np,$j

	ld	$nj,($nj)

	dmultu	$aj,$bi

	daddu	$lo0,$alo,$hi0

	daddu	$lo1,$nlo,$hi1

	sltu	AT,$lo0,$hi0

	sltu	s7,$lo1,$hi1

	daddu	$hi0,$ahi,AT

	daddu	$hi1,$nhi,s7

	mflo	$alo

	mfhi	$ahi

	daddu	$lo0,$tj

	addu	$j,8

	dmultu	$nj,$m1

	sltu	AT,$lo0,$tj

	daddu	$lo1,$lo0

	daddu	$hi0,AT

	sltu	s7,$lo1,$lo0

	ld	$tj,16($tp)

	daddu	$hi1,s7

	sltu	AT,$j,$num

	mflo	$nlo

	mfhi	$nhi

	sd	$lo1,($tp)

	bnez	AT,.Linner

	PTR_ADD	$tp,8

	.set	reorder

	daddu	$lo0,$alo,$hi0

	sltu	AT,$lo0,$hi0

	daddu	$hi0,$ahi,AT

	daddu	$lo0,$tj

	sltu	s7,$lo0,$tj

	daddu	$hi0,s7

	ld	$tj,16($tp)

	daddu	$lo1,$nlo,$hi1

	sltu	AT,$lo1,$hi1

	daddu	$hi1,$nhi,AT

	daddu	$lo1,$lo0

	sltu	s7,$lo1,$lo0

	daddu	$hi1,s7

	sd	$lo1,($tp)

	daddu	$lo1,$hi1,$hi0

	sltu	$hi1,$lo1,$hi0

	daddu	$lo1,$tj

	sltu	AT,$lo1,$tj

	daddu	$hi1,AT

	sd	$lo1,8($tp)

	sd	$hi1,16($tp)

	addu	$i,8

	sltu	s7,$i,$num

	bnez	s7,.Louter

	.set	noreorder

	PTR_ADD	$ap,sp,$num

	move	$tp,sp

	bnez	$hi1,.Lsub

	li	$hi0,0

	sgeu	AT,$lo1,$nj

	beqz	AT,.Lsub

	nop

.align	4

.Lcopy:	ld	AT,($tp)

	PTR_ADD	$tp,8

	sd	AT,($rp)

	sltu	AT,$tp,$ap

	sd	zero,-8($tp)

	bnez	AT,.Lcopy

	PTR_ADD	$rp,8

.Lexit:

	ld	s0,0($fp)

	ld	s1,8($fp)

	ld	s2,16($fp)

	ld	s3,24($fp)

	ld	s4,32($fp)

	ld	s5,40($fp)

	ld	s6,48($fp)

	ld	s7,56($fp)

	li	v0,1

	jr	ra

	PTR_ADD	sp,$fp,64

.align	4

.Lsub:	ld	$lo0,($tp)

	ld	$lo1,($np)

	dsubu	$lo1,$lo0,$lo1

	sgtu	AT,$lo1,$lo0

	dsubu	$lo0,$lo1,$hi0

	sgtu	$hi0,$lo0,$lo1

	PTR_ADD	$tp,8

	or	$hi0,AT

	PTR_ADD	$np,8

	sd	$lo0,($rp)

	sltu	AT,$tp,$ap

	bnez	AT,.Lsub

	PTR_ADD	$rp,8

	dsubu	$hi0,$hi1,$hi0

	move	$tp,sp

	sgtu	AT,$hi0,$hi1

	bnez	AT,.Lcopy

	PTR_SUB	$rp,$num

.align	4

.Lzap:	sd	zero,($tp)

	sltu	AT,$tp,$ap

	bnez	AT,.Lzap

	PTR_ADD	$tp,8

	b	.Lexit

	nop

	.set	reorder

END(bn_mul_mont)

.rdata

.asciiz	"Montgomery Multiplication for MIPS III/IV, CRYPTOGAMS by <appro\@openssl.org>"

___

print $code;

close STDOUT;