crypto: crct10dif - Accelerated CRC T10 DIF computation with PCLMULQDQ instruction

This is the x86_64 CRC T10 DIF transform accelerated with the PCLMULQDQ
instructions.  Details discussing the implementation can be found in the
paper:

"Fast CRC Computation for Generic Polynomials Using PCLMULQDQ Instruction"
http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 643 insertions, 0 deletions

diff --git a/arch/x86/crypto/crct10dif-pcl-asm_64.S b/arch/x86/crypto/crct10dif-pcl-asm_64.S
new file mode 100644
index 0000000..35e9756
--- /dev/null
+++ b/arch/x86/crypto/crct10dif-pcl-asm_64.S
@@ -0,0 +1,643 @@
+########################################################################
+# Implement fast CRC-T10DIF computation with SSE and PCLMULQDQ instructions
+#
+# Copyright (c) 2013, Intel Corporation
+#
+# Authors:
+#     Erdinc Ozturk <erdinc.ozturk@intel.com>
+#     Vinodh Gopal <vinodh.gopal@intel.com>
+#     James Guilford <james.guilford@intel.com>
+#     Tim Chen <tim.c.chen@linux.intel.com>
+#
+# This software is available to you under a choice of one of two
+# licenses.  You may choose to be licensed under the terms of the GNU
+# General Public License (GPL) Version 2, available from the file
+# COPYING in the main directory of this source tree, or the
+# OpenIB.org BSD license below:
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+# * Redistributions of source code must retain the above copyright
+#   notice, this list of conditions and the following disclaimer.
+#
+# * Redistributions in binary form must reproduce the above copyright
+#   notice, this list of conditions and the following disclaimer in the
+#   documentation and/or other materials provided with the
+#   distribution.
+#
+# * Neither the name of the Intel Corporation nor the names of its
+#   contributors may be used to endorse or promote products derived from
+#   this software without specific prior written permission.
+#
+#
+# THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION ""AS IS"" AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL CORPORATION OR
+# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+########################################################################
+#       Function API:
+#       UINT16 crc_t10dif_pcl(
+#               UINT16 init_crc, //initial CRC value, 16 bits
+#               const unsigned char *buf, //buffer pointer to calculate CRC on
+#               UINT64 len //buffer length in bytes (64-bit data)
+#       );
+#
+#       Reference paper titled "Fast CRC Computation for Generic
+#	Polynomials Using PCLMULQDQ Instruction"
+#       URL: http://www.intel.com/content/dam/www/public/us/en/documents
+#  /white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
+#
+#
+
+#include <linux/linkage.h>
+
+.text
+
+#define        arg1 %rdi
+#define        arg2 %rsi
+#define        arg3 %rdx
+
+#define        arg1_low32 %edi
+
+ENTRY(crc_t10dif_pcl)
+.align 16
+
+	# adjust the 16-bit initial_crc value, scale it to 32 bits
+	shl	$16, arg1_low32
+
+	# Allocate Stack Space
+	mov     %rsp, %rcx
+	sub	$16*2, %rsp
+	# align stack to 16 byte boundary
+	and     $~(0x10 - 1), %rsp
+
+	# check if smaller than 256
+	cmp	$256, arg3
+
+	# for sizes less than 128, we can't fold 64B at a time...
+	jl	_less_than_128
+
+
+	# load the initial crc value
+	movd	arg1_low32, %xmm10	# initial crc
+
+	# crc value does not need to be byte-reflected, but it needs
+	# to be moved to the high part of the register.
+	# because data will be byte-reflected and will align with
+	# initial crc at correct place.
+	pslldq	$12, %xmm10
+
+	movdqa  SHUF_MASK(%rip), %xmm11
+	# receive the initial 64B data, xor the initial crc value
+	movdqu	16*0(arg2), %xmm0
+	movdqu	16*1(arg2), %xmm1
+	movdqu	16*2(arg2), %xmm2
+	movdqu	16*3(arg2), %xmm3
+	movdqu	16*4(arg2), %xmm4
+	movdqu	16*5(arg2), %xmm5
+	movdqu	16*6(arg2), %xmm6
+	movdqu	16*7(arg2), %xmm7
+
+	pshufb	%xmm11, %xmm0
+	# XOR the initial_crc value
+	pxor	%xmm10, %xmm0
+	pshufb	%xmm11, %xmm1
+	pshufb	%xmm11, %xmm2
+	pshufb	%xmm11, %xmm3
+	pshufb	%xmm11, %xmm4
+	pshufb	%xmm11, %xmm5
+	pshufb	%xmm11, %xmm6
+	pshufb	%xmm11, %xmm7
+
+	movdqa	rk3(%rip), %xmm10	#xmm10 has rk3 and rk4
+					#imm value of pclmulqdq instruction
+					#will determine which constant to use
+
+	#################################################################
+	# we subtract 256 instead of 128 to save one instruction from the loop
+	sub	$256, arg3
+
+	# at this section of the code, there is 64*x+y (0<=y<64) bytes of
+	# buffer. The _fold_64_B_loop will fold 64B at a time
+	# until we have 64+y Bytes of buffer
+
+
+	# fold 64B at a time. This section of the code folds 4 xmm
+	# registers in parallel
+_fold_64_B_loop:
+
+	# update the buffer pointer
+	add	$128, arg2		#    buf += 64#
+
+	movdqu	16*0(arg2), %xmm9
+	movdqu	16*1(arg2), %xmm12
+	pshufb	%xmm11, %xmm9
+	pshufb	%xmm11, %xmm12
+	movdqa	%xmm0, %xmm8
+	movdqa	%xmm1, %xmm13
+	pclmulqdq	$0x0 , %xmm10, %xmm0
+	pclmulqdq	$0x11, %xmm10, %xmm8
+	pclmulqdq	$0x0 , %xmm10, %xmm1
+	pclmulqdq	$0x11, %xmm10, %xmm13
+	pxor	%xmm9 , %xmm0
+	xorps	%xmm8 , %xmm0
+	pxor	%xmm12, %xmm1
+	xorps	%xmm13, %xmm1
+
+	movdqu	16*2(arg2), %xmm9
+	movdqu	16*3(arg2), %xmm12
+	pshufb	%xmm11, %xmm9
+	pshufb	%xmm11, %xmm12
+	movdqa	%xmm2, %xmm8
+	movdqa	%xmm3, %xmm13
+	pclmulqdq	$0x0, %xmm10, %xmm2
+	pclmulqdq	$0x11, %xmm10, %xmm8
+	pclmulqdq	$0x0, %xmm10, %xmm3
+	pclmulqdq	$0x11, %xmm10, %xmm13
+	pxor	%xmm9 , %xmm2
+	xorps	%xmm8 , %xmm2
+	pxor	%xmm12, %xmm3
+	xorps	%xmm13, %xmm3
+
+	movdqu	16*4(arg2), %xmm9
+	movdqu	16*5(arg2), %xmm12
+	pshufb	%xmm11, %xmm9
+	pshufb	%xmm11, %xmm12
+	movdqa	%xmm4, %xmm8
+	movdqa	%xmm5, %xmm13
+	pclmulqdq	$0x0,  %xmm10, %xmm4
+	pclmulqdq	$0x11, %xmm10, %xmm8
+	pclmulqdq	$0x0,  %xmm10, %xmm5
+	pclmulqdq	$0x11, %xmm10, %xmm13
+	pxor	%xmm9 ,  %xmm4
+	xorps	%xmm8 ,  %xmm4
+	pxor	%xmm12,  %xmm5
+	xorps	%xmm13,  %xmm5
+
+	movdqu	16*6(arg2), %xmm9
+	movdqu	16*7(arg2), %xmm12
+	pshufb	%xmm11, %xmm9
+	pshufb	%xmm11, %xmm12
+	movdqa	%xmm6 , %xmm8
+	movdqa	%xmm7 , %xmm13
+	pclmulqdq	$0x0 , %xmm10, %xmm6
+	pclmulqdq	$0x11, %xmm10, %xmm8
+	pclmulqdq	$0x0 , %xmm10, %xmm7
+	pclmulqdq	$0x11, %xmm10, %xmm13
+	pxor	%xmm9 , %xmm6
+	xorps	%xmm8 , %xmm6
+	pxor	%xmm12, %xmm7
+	xorps	%xmm13, %xmm7
+
+	sub	$128, arg3
+
+	# check if there is another 64B in the buffer to be able to fold
+	jge	_fold_64_B_loop
+	##################################################################
+
+
+	add	$128, arg2
+	# at this point, the buffer pointer is pointing at the last y Bytes
+	# of the buffer the 64B of folded data is in 4 of the xmm
+	# registers: xmm0, xmm1, xmm2, xmm3
+
+
+	# fold the 8 xmm registers to 1 xmm register with different constants
+
+	movdqa	rk9(%rip), %xmm10
+	movdqa	%xmm0, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm0
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	xorps	%xmm0, %xmm7
+
+	movdqa	rk11(%rip), %xmm10
+	movdqa	%xmm1, %xmm8
+	pclmulqdq	 $0x11, %xmm10, %xmm1
+	pclmulqdq	 $0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	xorps	%xmm1, %xmm7
+
+	movdqa	rk13(%rip), %xmm10
+	movdqa	%xmm2, %xmm8
+	pclmulqdq	 $0x11, %xmm10, %xmm2
+	pclmulqdq	 $0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	pxor	%xmm2, %xmm7
+
+	movdqa	rk15(%rip), %xmm10
+	movdqa	%xmm3, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm3
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	xorps	%xmm3, %xmm7
+
+	movdqa	rk17(%rip), %xmm10
+	movdqa	%xmm4, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm4
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	pxor	%xmm4, %xmm7
+
+	movdqa	rk19(%rip), %xmm10
+	movdqa	%xmm5, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm5
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	xorps	%xmm5, %xmm7
+
+	movdqa	rk1(%rip), %xmm10	#xmm10 has rk1 and rk2
+					#imm value of pclmulqdq instruction
+					#will determine which constant to use
+	movdqa	%xmm6, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm6
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	pxor	%xmm6, %xmm7
+
+
+	# instead of 64, we add 48 to the loop counter to save 1 instruction
+	# from the loop instead of a cmp instruction, we use the negative
+	# flag with the jl instruction
+	add	$128-16, arg3
+	jl	_final_reduction_for_128
+
+	# now we have 16+y bytes left to reduce. 16 Bytes is in register xmm7
+	# and the rest is in memory. We can fold 16 bytes at a time if y>=16
+	# continue folding 16B at a time
+
+_16B_reduction_loop:
+	movdqa	%xmm7, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm7
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	movdqu	(arg2), %xmm0
+	pshufb	%xmm11, %xmm0
+	pxor	%xmm0 , %xmm7
+	add	$16, arg2
+	sub	$16, arg3
+	# instead of a cmp instruction, we utilize the flags with the
+	# jge instruction equivalent of: cmp arg3, 16-16
+	# check if there is any more 16B in the buffer to be able to fold
+	jge	_16B_reduction_loop
+
+	#now we have 16+z bytes left to reduce, where 0<= z < 16.
+	#first, we reduce the data in the xmm7 register
+
+
+_final_reduction_for_128:
+	# check if any more data to fold. If not, compute the CRC of
+	# the final 128 bits
+	add	$16, arg3
+	je	_128_done
+
+	# here we are getting data that is less than 16 bytes.
+	# since we know that there was data before the pointer, we can
+	# offset the input pointer before the actual point, to receive
+	# exactly 16 bytes. after that the registers need to be adjusted.
+_get_last_two_xmms:
+	movdqa	%xmm7, %xmm2
+
+	movdqu	-16(arg2, arg3), %xmm1
+	pshufb	%xmm11, %xmm1
+
+	# get rid of the extra data that was loaded before
+	# load the shift constant
+	lea	pshufb_shf_table+16(%rip), %rax
+	sub	arg3, %rax
+	movdqu	(%rax), %xmm0
+
+	# shift xmm2 to the left by arg3 bytes
+	pshufb	%xmm0, %xmm2
+
+	# shift xmm7 to the right by 16-arg3 bytes
+	pxor	mask1(%rip), %xmm0
+	pshufb	%xmm0, %xmm7
+	pblendvb	%xmm2, %xmm1	#xmm0 is implicit
+
+	# fold 16 Bytes
+	movdqa	%xmm1, %xmm2
+	movdqa	%xmm7, %xmm8
+	pclmulqdq	$0x11, %xmm10, %xmm7
+	pclmulqdq	$0x0 , %xmm10, %xmm8
+	pxor	%xmm8, %xmm7
+	pxor	%xmm2, %xmm7
+
+_128_done:
+	# compute crc of a 128-bit value
+	movdqa	rk5(%rip), %xmm10	# rk5 and rk6 in xmm10
+	movdqa	%xmm7, %xmm0
+
+	#64b fold
+	pclmulqdq	$0x1, %xmm10, %xmm7
+	pslldq	$8   ,  %xmm0
+	pxor	%xmm0,  %xmm7
+
+	#32b fold
+	movdqa	%xmm7, %xmm0
+
+	pand	mask2(%rip), %xmm0
+
+	psrldq	$12, %xmm7
+	pclmulqdq	$0x10, %xmm10, %xmm7
+	pxor	%xmm0, %xmm7
+
+	#barrett reduction
+_barrett:
+	movdqa	rk7(%rip), %xmm10	# rk7 and rk8 in xmm10
+	movdqa	%xmm7, %xmm0
+	pclmulqdq	$0x01, %xmm10, %xmm7
+	pslldq	$4, %xmm7
+	pclmulqdq	$0x11, %xmm10, %xmm7
+
+	pslldq	$4, %xmm7
+	pxor	%xmm0, %xmm7
+	pextrd	$1, %xmm7, %eax
+
+_cleanup:
+	# scale the result back to 16 bits
+	shr	$16, %eax
+	mov     %rcx, %rsp
+	ret
+
+########################################################################
+
+.align 16
+_less_than_128:
+
+	# check if there is enough buffer to be able to fold 16B at a time
+	cmp	$32, arg3
+	jl	_less_than_32
+	movdqa  SHUF_MASK(%rip), %xmm11
+
+	# now if there is, load the constants
+	movdqa	rk1(%rip), %xmm10	# rk1 and rk2 in xmm10
+
+	movd	arg1_low32, %xmm0	# get the initial crc value
+	pslldq	$12, %xmm0	# align it to its correct place
+	movdqu	(arg2), %xmm7	# load the plaintext
+	pshufb	%xmm11, %xmm7	# byte-reflect the plaintext
+	pxor	%xmm0, %xmm7
+
+
+	# update the buffer pointer
+	add	$16, arg2
+
+	# update the counter. subtract 32 instead of 16 to save one
+	# instruction from the loop
+	sub	$32, arg3
+
+	jmp	_16B_reduction_loop
+
+
+.align 16
+_less_than_32:
+	# mov initial crc to the return value. this is necessary for
+	# zero-length buffers.
+	mov	arg1_low32, %eax
+	test	arg3, arg3
+	je	_cleanup
+
+	movdqa  SHUF_MASK(%rip), %xmm11
+
+	movd	arg1_low32, %xmm0	# get the initial crc value
+	pslldq	$12, %xmm0	# align it to its correct place
+
+	cmp	$16, arg3
+	je	_exact_16_left
+	jl	_less_than_16_left
+
+	movdqu	(arg2), %xmm7	# load the plaintext
+	pshufb	%xmm11, %xmm7	# byte-reflect the plaintext
+	pxor	%xmm0 , %xmm7	# xor the initial crc value
+	add	$16, arg2
+	sub	$16, arg3
+	movdqa	rk1(%rip), %xmm10	# rk1 and rk2 in xmm10
+	jmp	_get_last_two_xmms
+
+
+.align 16
+_less_than_16_left:
+	# use stack space to load data less than 16 bytes, zero-out
+	# the 16B in memory first.
+
+	pxor	%xmm1, %xmm1
+	mov	%rsp, %r11
+	movdqa	%xmm1, (%r11)
+
+	cmp	$4, arg3
+	jl	_only_less_than_4
+
+	# backup the counter value
+	mov	arg3, %r9
+	cmp	$8, arg3
+	jl	_less_than_8_left
+
+	# load 8 Bytes
+	mov	(arg2), %rax
+	mov	%rax, (%r11)
+	add	$8, %r11
+	sub	$8, arg3
+	add	$8, arg2
+_less_than_8_left:
+
+	cmp	$4, arg3
+	jl	_less_than_4_left
+
+	# load 4 Bytes
+	mov	(arg2), %eax
+	mov	%eax, (%r11)
+	add	$4, %r11
+	sub	$4, arg3
+	add	$4, arg2
+_less_than_4_left:
+
+	cmp	$2, arg3
+	jl	_less_than_2_left
+
+	# load 2 Bytes
+	mov	(arg2), %ax
+	mov	%ax, (%r11)
+	add	$2, %r11
+	sub	$2, arg3
+	add	$2, arg2
+_less_than_2_left:
+	cmp     $1, arg3
+        jl      _zero_left
+
+	# load 1 Byte
+	mov	(arg2), %al
+	mov	%al, (%r11)
+_zero_left:
+	movdqa	(%rsp), %xmm7
+	pshufb	%xmm11, %xmm7
+	pxor	%xmm0 , %xmm7	# xor the initial crc value
+
+	# shl r9, 4
+	lea	pshufb_shf_table+16(%rip), %rax
+	sub	%r9, %rax
+	movdqu	(%rax), %xmm0
+	pxor	mask1(%rip), %xmm0
+
+	pshufb	%xmm0, %xmm7
+	jmp	_128_done
+
+.align 16
+_exact_16_left:
+	movdqu	(arg2), %xmm7
+	pshufb	%xmm11, %xmm7
+	pxor	%xmm0 , %xmm7   # xor the initial crc value
+
+	jmp	_128_done
+
+_only_less_than_4:
+	cmp	$3, arg3
+	jl	_only_less_than_3
+
+	# load 3 Bytes
+	mov	(arg2), %al
+	mov	%al, (%r11)
+
+	mov	1(arg2), %al
+	mov	%al, 1(%r11)
+
+	mov	2(arg2), %al
+	mov	%al, 2(%r11)
+
+	movdqa	 (%rsp), %xmm7
+	pshufb	 %xmm11, %xmm7
+	pxor	 %xmm0 , %xmm7  # xor the initial crc value
+
+	psrldq	$5, %xmm7
+
+	jmp	_barrett
+_only_less_than_3:
+	cmp	$2, arg3
+	jl	_only_less_than_2
+
+	# load 2 Bytes
+	mov	(arg2), %al
+	mov	%al, (%r11)
+
+	mov	1(arg2), %al
+	mov	%al, 1(%r11)
+
+	movdqa	(%rsp), %xmm7
+	pshufb	%xmm11, %xmm7
+	pxor	%xmm0 , %xmm7   # xor the initial crc value
+
+	psrldq	$6, %xmm7
+
+	jmp	_barrett
+_only_less_than_2:
+
+	# load 1 Byte
+	mov	(arg2), %al
+	mov	%al, (%r11)
+
+	movdqa	(%rsp), %xmm7
+	pshufb	%xmm11, %xmm7
+	pxor	%xmm0 , %xmm7   # xor the initial crc value
+
+	psrldq	$7, %xmm7
+
+	jmp	_barrett
+
+ENDPROC(crc_t10dif_pcl)
+
+.data
+
+# precomputed constants
+# these constants are precomputed from the poly:
+# 0x8bb70000 (0x8bb7 scaled to 32 bits)
+.align 16
+# Q = 0x18BB70000
+# rk1 = 2^(32*3) mod Q << 32
+# rk2 = 2^(32*5) mod Q << 32
+# rk3 = 2^(32*15) mod Q << 32
+# rk4 = 2^(32*17) mod Q << 32
+# rk5 = 2^(32*3) mod Q << 32
+# rk6 = 2^(32*2) mod Q << 32
+# rk7 = floor(2^64/Q)
+# rk8 = Q
+rk1:
+.quad 0x2d56000000000000
+rk2:
+.quad 0x06df000000000000
+rk3:
+.quad 0x9d9d000000000000
+rk4:
+.quad 0x7cf5000000000000
+rk5:
+.quad 0x2d56000000000000
+rk6:
+.quad 0x1368000000000000
+rk7:
+.quad 0x00000001f65a57f8
+rk8:
+.quad 0x000000018bb70000
+
+rk9:
+.quad 0xceae000000000000
+rk10:
+.quad 0xbfd6000000000000
+rk11:
+.quad 0x1e16000000000000
+rk12:
+.quad 0x713c000000000000
+rk13:
+.quad 0xf7f9000000000000
+rk14:
+.quad 0x80a6000000000000
+rk15:
+.quad 0x044c000000000000
+rk16:
+.quad 0xe658000000000000
+rk17:
+.quad 0xad18000000000000
+rk18:
+.quad 0xa497000000000000
+rk19:
+.quad 0x6ee3000000000000
+rk20:
+.quad 0xe7b5000000000000
+
+
+
+mask1:
+.octa 0x80808080808080808080808080808080
+mask2:
+.octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF
+
+SHUF_MASK:
+.octa 0x000102030405060708090A0B0C0D0E0F
+
+pshufb_shf_table:
+# use these values for shift constants for the pshufb instruction
+# different alignments result in values as shown:
+#	DDQ 0x008f8e8d8c8b8a898887868584838281 # shl 15 (16-1) / shr1
+#	DDQ 0x01008f8e8d8c8b8a8988878685848382 # shl 14 (16-3) / shr2
+#	DDQ 0x0201008f8e8d8c8b8a89888786858483 # shl 13 (16-4) / shr3
+#	DDQ 0x030201008f8e8d8c8b8a898887868584 # shl 12 (16-4) / shr4
+#	DDQ 0x04030201008f8e8d8c8b8a8988878685 # shl 11 (16-5) / shr5
+#	DDQ 0x0504030201008f8e8d8c8b8a89888786 # shl 10 (16-6) / shr6
+#	DDQ 0x060504030201008f8e8d8c8b8a898887 # shl 9  (16-7) / shr7
+#	DDQ 0x07060504030201008f8e8d8c8b8a8988 # shl 8  (16-8) / shr8
+#	DDQ 0x0807060504030201008f8e8d8c8b8a89 # shl 7  (16-9) / shr9
+#	DDQ 0x090807060504030201008f8e8d8c8b8a # shl 6  (16-10) / shr10
+#	DDQ 0x0a090807060504030201008f8e8d8c8b # shl 5  (16-11) / shr11
+#	DDQ 0x0b0a090807060504030201008f8e8d8c # shl 4  (16-12) / shr12
+#	DDQ 0x0c0b0a090807060504030201008f8e8d # shl 3  (16-13) / shr13
+#	DDQ 0x0d0c0b0a090807060504030201008f8e # shl 2  (16-14) / shr14
+#	DDQ 0x0e0d0c0b0a090807060504030201008f # shl 1  (16-15) / shr15
+.octa 0x8f8e8d8c8b8a89888786858483828100
+.octa 0x000e0d0c0b0a09080706050403020100