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![Eric Biggers](/assets/img/avatar_default.png)
Add an ARM NEON-accelerated implementation of Speck-XTS. It operates on 128-byte chunks at a time, i.e. 8 blocks for Speck128 or 16 blocks for Speck64. Each 128-byte chunk goes through XTS preprocessing, then is encrypted/decrypted (doing one cipher round for all the blocks, then the next round, etc.), then goes through XTS postprocessing. The performance depends on the processor but can be about 3 times faster than the generic code. For example, on an ARMv7 processor we observe the following performance with Speck128/256-XTS: xts-speck128-neon: Encryption 107.9 MB/s, Decryption 108.1 MB/s xts(speck128-generic): Encryption 32.1 MB/s, Decryption 36.6 MB/s In comparison to AES-256-XTS without the Cryptography Extensions: xts-aes-neonbs: Encryption 41.2 MB/s, Decryption 36.7 MB/s xts(aes-asm): Encryption 31.7 MB/s, Decryption 30.8 MB/s xts(aes-generic): Encryption 21.2 MB/s, Decryption 20.9 MB/s Speck64/128-XTS is even faster: xts-speck64-neon: Encryption 138.6 MB/s, Decryption 139.1 MB/s Note that as with the generic code, only the Speck128 and Speck64 variants are supported. Also, for now only the XTS mode of operation is supported, to target the disk and file encryption use cases. The NEON code also only handles the portion of the data that is evenly divisible into 128-byte chunks, with any remainder handled by a C fallback. Of course, other modes of operation could be added later if needed, and/or the NEON code could be updated to handle other buffer sizes. The XTS specification is only defined for AES which has a 128-bit block size, so for the GF(2^64) math needed for Speck64-XTS we use the reducing polynomial 'x^64 + x^4 + x^3 + x + 1' given by the original XEX paper. Of course, when possible users should use Speck128-XTS, but even that may be too slow on some processors; Speck64-XTS can be faster. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
432 lines
10 KiB
ArmAsm
432 lines
10 KiB
ArmAsm
// SPDX-License-Identifier: GPL-2.0
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/*
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* NEON-accelerated implementation of Speck128-XTS and Speck64-XTS
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*
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* Copyright (c) 2018 Google, Inc
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*
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* Author: Eric Biggers <ebiggers@google.com>
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*/
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#include <linux/linkage.h>
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.text
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.fpu neon
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// arguments
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ROUND_KEYS .req r0 // const {u64,u32} *round_keys
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NROUNDS .req r1 // int nrounds
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DST .req r2 // void *dst
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SRC .req r3 // const void *src
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NBYTES .req r4 // unsigned int nbytes
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TWEAK .req r5 // void *tweak
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// registers which hold the data being encrypted/decrypted
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X0 .req q0
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X0_L .req d0
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X0_H .req d1
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Y0 .req q1
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Y0_H .req d3
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X1 .req q2
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X1_L .req d4
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X1_H .req d5
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Y1 .req q3
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Y1_H .req d7
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X2 .req q4
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X2_L .req d8
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X2_H .req d9
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Y2 .req q5
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Y2_H .req d11
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X3 .req q6
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X3_L .req d12
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X3_H .req d13
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Y3 .req q7
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Y3_H .req d15
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// the round key, duplicated in all lanes
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ROUND_KEY .req q8
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ROUND_KEY_L .req d16
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ROUND_KEY_H .req d17
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// index vector for vtbl-based 8-bit rotates
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ROTATE_TABLE .req d18
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// multiplication table for updating XTS tweaks
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GF128MUL_TABLE .req d19
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GF64MUL_TABLE .req d19
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// current XTS tweak value(s)
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TWEAKV .req q10
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TWEAKV_L .req d20
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TWEAKV_H .req d21
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TMP0 .req q12
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TMP0_L .req d24
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TMP0_H .req d25
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TMP1 .req q13
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TMP2 .req q14
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TMP3 .req q15
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.align 4
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.Lror64_8_table:
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.byte 1, 2, 3, 4, 5, 6, 7, 0
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.Lror32_8_table:
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.byte 1, 2, 3, 0, 5, 6, 7, 4
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.Lrol64_8_table:
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.byte 7, 0, 1, 2, 3, 4, 5, 6
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.Lrol32_8_table:
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.byte 3, 0, 1, 2, 7, 4, 5, 6
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.Lgf128mul_table:
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.byte 0, 0x87
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.fill 14
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.Lgf64mul_table:
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.byte 0, 0x1b, (0x1b << 1), (0x1b << 1) ^ 0x1b
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.fill 12
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/*
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* _speck_round_128bytes() - Speck encryption round on 128 bytes at a time
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*
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* Do one Speck encryption round on the 128 bytes (8 blocks for Speck128, 16 for
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* Speck64) stored in X0-X3 and Y0-Y3, using the round key stored in all lanes
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* of ROUND_KEY. 'n' is the lane size: 64 for Speck128, or 32 for Speck64.
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*
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* The 8-bit rotates are implemented using vtbl instead of vshr + vsli because
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* the vtbl approach is faster on some processors and the same speed on others.
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*/
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.macro _speck_round_128bytes n
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// x = ror(x, 8)
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vtbl.8 X0_L, {X0_L}, ROTATE_TABLE
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vtbl.8 X0_H, {X0_H}, ROTATE_TABLE
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vtbl.8 X1_L, {X1_L}, ROTATE_TABLE
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vtbl.8 X1_H, {X1_H}, ROTATE_TABLE
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vtbl.8 X2_L, {X2_L}, ROTATE_TABLE
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vtbl.8 X2_H, {X2_H}, ROTATE_TABLE
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vtbl.8 X3_L, {X3_L}, ROTATE_TABLE
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vtbl.8 X3_H, {X3_H}, ROTATE_TABLE
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// x += y
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vadd.u\n X0, Y0
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vadd.u\n X1, Y1
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vadd.u\n X2, Y2
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vadd.u\n X3, Y3
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// x ^= k
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veor X0, ROUND_KEY
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veor X1, ROUND_KEY
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veor X2, ROUND_KEY
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veor X3, ROUND_KEY
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// y = rol(y, 3)
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vshl.u\n TMP0, Y0, #3
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vshl.u\n TMP1, Y1, #3
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vshl.u\n TMP2, Y2, #3
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vshl.u\n TMP3, Y3, #3
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vsri.u\n TMP0, Y0, #(\n - 3)
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vsri.u\n TMP1, Y1, #(\n - 3)
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vsri.u\n TMP2, Y2, #(\n - 3)
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vsri.u\n TMP3, Y3, #(\n - 3)
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// y ^= x
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veor Y0, TMP0, X0
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veor Y1, TMP1, X1
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veor Y2, TMP2, X2
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veor Y3, TMP3, X3
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.endm
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/*
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* _speck_unround_128bytes() - Speck decryption round on 128 bytes at a time
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*
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* This is the inverse of _speck_round_128bytes().
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*/
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.macro _speck_unround_128bytes n
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// y ^= x
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veor TMP0, Y0, X0
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veor TMP1, Y1, X1
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veor TMP2, Y2, X2
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veor TMP3, Y3, X3
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// y = ror(y, 3)
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vshr.u\n Y0, TMP0, #3
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vshr.u\n Y1, TMP1, #3
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vshr.u\n Y2, TMP2, #3
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vshr.u\n Y3, TMP3, #3
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vsli.u\n Y0, TMP0, #(\n - 3)
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vsli.u\n Y1, TMP1, #(\n - 3)
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vsli.u\n Y2, TMP2, #(\n - 3)
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vsli.u\n Y3, TMP3, #(\n - 3)
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// x ^= k
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veor X0, ROUND_KEY
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veor X1, ROUND_KEY
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veor X2, ROUND_KEY
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veor X3, ROUND_KEY
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// x -= y
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vsub.u\n X0, Y0
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vsub.u\n X1, Y1
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vsub.u\n X2, Y2
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vsub.u\n X3, Y3
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// x = rol(x, 8);
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vtbl.8 X0_L, {X0_L}, ROTATE_TABLE
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vtbl.8 X0_H, {X0_H}, ROTATE_TABLE
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vtbl.8 X1_L, {X1_L}, ROTATE_TABLE
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vtbl.8 X1_H, {X1_H}, ROTATE_TABLE
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vtbl.8 X2_L, {X2_L}, ROTATE_TABLE
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vtbl.8 X2_H, {X2_H}, ROTATE_TABLE
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vtbl.8 X3_L, {X3_L}, ROTATE_TABLE
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vtbl.8 X3_H, {X3_H}, ROTATE_TABLE
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.endm
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.macro _xts128_precrypt_one dst_reg, tweak_buf, tmp
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// Load the next source block
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vld1.8 {\dst_reg}, [SRC]!
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// Save the current tweak in the tweak buffer
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vst1.8 {TWEAKV}, [\tweak_buf:128]!
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// XOR the next source block with the current tweak
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veor \dst_reg, TWEAKV
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/*
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* Calculate the next tweak by multiplying the current one by x,
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* modulo p(x) = x^128 + x^7 + x^2 + x + 1.
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*/
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vshr.u64 \tmp, TWEAKV, #63
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vshl.u64 TWEAKV, #1
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veor TWEAKV_H, \tmp\()_L
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vtbl.8 \tmp\()_H, {GF128MUL_TABLE}, \tmp\()_H
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veor TWEAKV_L, \tmp\()_H
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.endm
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.macro _xts64_precrypt_two dst_reg, tweak_buf, tmp
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// Load the next two source blocks
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vld1.8 {\dst_reg}, [SRC]!
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// Save the current two tweaks in the tweak buffer
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vst1.8 {TWEAKV}, [\tweak_buf:128]!
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// XOR the next two source blocks with the current two tweaks
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veor \dst_reg, TWEAKV
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/*
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* Calculate the next two tweaks by multiplying the current ones by x^2,
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* modulo p(x) = x^64 + x^4 + x^3 + x + 1.
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*/
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vshr.u64 \tmp, TWEAKV, #62
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vshl.u64 TWEAKV, #2
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vtbl.8 \tmp\()_L, {GF64MUL_TABLE}, \tmp\()_L
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vtbl.8 \tmp\()_H, {GF64MUL_TABLE}, \tmp\()_H
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veor TWEAKV, \tmp
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.endm
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/*
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* _speck_xts_crypt() - Speck-XTS encryption/decryption
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*
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* Encrypt or decrypt NBYTES bytes of data from the SRC buffer to the DST buffer
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* using Speck-XTS, specifically the variant with a block size of '2n' and round
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* count given by NROUNDS. The expanded round keys are given in ROUND_KEYS, and
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* the current XTS tweak value is given in TWEAK. It's assumed that NBYTES is a
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* nonzero multiple of 128.
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*/
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.macro _speck_xts_crypt n, decrypting
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push {r4-r7}
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mov r7, sp
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/*
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* The first four parameters were passed in registers r0-r3. Load the
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* additional parameters, which were passed on the stack.
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*/
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ldr NBYTES, [sp, #16]
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ldr TWEAK, [sp, #20]
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/*
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* If decrypting, modify the ROUND_KEYS parameter to point to the last
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* round key rather than the first, since for decryption the round keys
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* are used in reverse order.
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*/
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.if \decrypting
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.if \n == 64
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add ROUND_KEYS, ROUND_KEYS, NROUNDS, lsl #3
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sub ROUND_KEYS, #8
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.else
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add ROUND_KEYS, ROUND_KEYS, NROUNDS, lsl #2
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sub ROUND_KEYS, #4
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.endif
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.endif
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// Load the index vector for vtbl-based 8-bit rotates
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.if \decrypting
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ldr r12, =.Lrol\n\()_8_table
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.else
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ldr r12, =.Lror\n\()_8_table
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.endif
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vld1.8 {ROTATE_TABLE}, [r12:64]
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// One-time XTS preparation
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/*
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* Allocate stack space to store 128 bytes worth of tweaks. For
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* performance, this space is aligned to a 16-byte boundary so that we
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* can use the load/store instructions that declare 16-byte alignment.
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*/
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sub sp, #128
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bic sp, #0xf
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.if \n == 64
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// Load first tweak
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vld1.8 {TWEAKV}, [TWEAK]
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// Load GF(2^128) multiplication table
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ldr r12, =.Lgf128mul_table
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vld1.8 {GF128MUL_TABLE}, [r12:64]
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.else
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// Load first tweak
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vld1.8 {TWEAKV_L}, [TWEAK]
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// Load GF(2^64) multiplication table
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ldr r12, =.Lgf64mul_table
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vld1.8 {GF64MUL_TABLE}, [r12:64]
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// Calculate second tweak, packing it together with the first
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vshr.u64 TMP0_L, TWEAKV_L, #63
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vtbl.u8 TMP0_L, {GF64MUL_TABLE}, TMP0_L
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vshl.u64 TWEAKV_H, TWEAKV_L, #1
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veor TWEAKV_H, TMP0_L
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.endif
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.Lnext_128bytes_\@:
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/*
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* Load the source blocks into {X,Y}[0-3], XOR them with their XTS tweak
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* values, and save the tweaks on the stack for later. Then
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* de-interleave the 'x' and 'y' elements of each block, i.e. make it so
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* that the X[0-3] registers contain only the second halves of blocks,
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* and the Y[0-3] registers contain only the first halves of blocks.
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* (Speck uses the order (y, x) rather than the more intuitive (x, y).)
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*/
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mov r12, sp
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.if \n == 64
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_xts128_precrypt_one X0, r12, TMP0
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_xts128_precrypt_one Y0, r12, TMP0
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_xts128_precrypt_one X1, r12, TMP0
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_xts128_precrypt_one Y1, r12, TMP0
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_xts128_precrypt_one X2, r12, TMP0
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_xts128_precrypt_one Y2, r12, TMP0
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_xts128_precrypt_one X3, r12, TMP0
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_xts128_precrypt_one Y3, r12, TMP0
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vswp X0_L, Y0_H
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vswp X1_L, Y1_H
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vswp X2_L, Y2_H
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vswp X3_L, Y3_H
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.else
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_xts64_precrypt_two X0, r12, TMP0
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_xts64_precrypt_two Y0, r12, TMP0
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_xts64_precrypt_two X1, r12, TMP0
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_xts64_precrypt_two Y1, r12, TMP0
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_xts64_precrypt_two X2, r12, TMP0
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_xts64_precrypt_two Y2, r12, TMP0
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_xts64_precrypt_two X3, r12, TMP0
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_xts64_precrypt_two Y3, r12, TMP0
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vuzp.32 Y0, X0
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vuzp.32 Y1, X1
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vuzp.32 Y2, X2
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vuzp.32 Y3, X3
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.endif
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// Do the cipher rounds
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mov r12, ROUND_KEYS
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mov r6, NROUNDS
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.Lnext_round_\@:
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.if \decrypting
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.if \n == 64
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vld1.64 ROUND_KEY_L, [r12]
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sub r12, #8
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vmov ROUND_KEY_H, ROUND_KEY_L
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.else
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vld1.32 {ROUND_KEY_L[],ROUND_KEY_H[]}, [r12]
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sub r12, #4
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.endif
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_speck_unround_128bytes \n
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.else
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.if \n == 64
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vld1.64 ROUND_KEY_L, [r12]!
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vmov ROUND_KEY_H, ROUND_KEY_L
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.else
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vld1.32 {ROUND_KEY_L[],ROUND_KEY_H[]}, [r12]!
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.endif
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_speck_round_128bytes \n
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.endif
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subs r6, r6, #1
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bne .Lnext_round_\@
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// Re-interleave the 'x' and 'y' elements of each block
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.if \n == 64
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vswp X0_L, Y0_H
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vswp X1_L, Y1_H
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vswp X2_L, Y2_H
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vswp X3_L, Y3_H
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.else
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vzip.32 Y0, X0
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vzip.32 Y1, X1
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vzip.32 Y2, X2
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vzip.32 Y3, X3
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.endif
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// XOR the encrypted/decrypted blocks with the tweaks we saved earlier
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mov r12, sp
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vld1.8 {TMP0, TMP1}, [r12:128]!
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vld1.8 {TMP2, TMP3}, [r12:128]!
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veor X0, TMP0
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veor Y0, TMP1
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veor X1, TMP2
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veor Y1, TMP3
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vld1.8 {TMP0, TMP1}, [r12:128]!
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vld1.8 {TMP2, TMP3}, [r12:128]!
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veor X2, TMP0
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veor Y2, TMP1
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veor X3, TMP2
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veor Y3, TMP3
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// Store the ciphertext in the destination buffer
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vst1.8 {X0, Y0}, [DST]!
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vst1.8 {X1, Y1}, [DST]!
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vst1.8 {X2, Y2}, [DST]!
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vst1.8 {X3, Y3}, [DST]!
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// Continue if there are more 128-byte chunks remaining, else return
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subs NBYTES, #128
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bne .Lnext_128bytes_\@
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// Store the next tweak
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.if \n == 64
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vst1.8 {TWEAKV}, [TWEAK]
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.else
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vst1.8 {TWEAKV_L}, [TWEAK]
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.endif
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mov sp, r7
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pop {r4-r7}
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bx lr
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.endm
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ENTRY(speck128_xts_encrypt_neon)
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_speck_xts_crypt n=64, decrypting=0
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ENDPROC(speck128_xts_encrypt_neon)
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ENTRY(speck128_xts_decrypt_neon)
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_speck_xts_crypt n=64, decrypting=1
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ENDPROC(speck128_xts_decrypt_neon)
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ENTRY(speck64_xts_encrypt_neon)
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_speck_xts_crypt n=32, decrypting=0
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ENDPROC(speck64_xts_encrypt_neon)
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ENTRY(speck64_xts_decrypt_neon)
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_speck_xts_crypt n=32, decrypting=1
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ENDPROC(speck64_xts_decrypt_neon)
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