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C arm/v6/aes-decrypt-internal.asm
ifelse(<
Copyright (C) 2013 Niels Möller
This file is part of GNU Nettle.
GNU Nettle is free software: you can redistribute it and/or
modify it under the terms of either:
* the GNU Lesser General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your
option) any later version.
or
* the GNU General Public License as published by the Free
Software Foundation; either version 2 of the License, or (at your
option) any later version.
or both in parallel, as here.
GNU Nettle is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received copies of the GNU General Public License and
the GNU Lesser General Public License along with this program. If
not, see http://www.gnu.org/licenses/.
>)
.arch armv6
include_src(<arm/aes.m4>)
define(<PARAM_ROUNDS>, <r0>)
define(<PARAM_KEYS>, <r1>)
define(<TABLE>, <r2>)
define(<LENGTH>, <r3>)
C On stack: DST, SRC
define(<W0>, <r4>)
define(<W1>, <r5>)
define(<W2>, <r6>)
define(<W3>, <r7>)
define(<T0>, <r8>)
define(<COUNT>, <r10>)
define(<KEY>, <r11>)
define(<X0>, <r0>) C Overlaps PARAM_ROUNDS and PARAM_KEYS
define(<X1>, <r1>)
define(<X2>, <r12>)
define(<X3>, <r14>) C lr
define(<FRAME_ROUNDS>>, <[sp]>)
define(<FRAME_KEYS>, <[sp, #+4]>)
C 8 saved registers
define(<FRAME_DST>, <[sp, #+40]>)
define(<FRAME_SRC>, <[sp, #+44]>)
define(<SRC>, <r12>) C Overlap registers used in inner loop.
define(<DST>, <COUNT>)
C AES_DECRYPT_ROUND(x0,x1,x2,x3,w0,w1,w2,w3,key)
define(<AES_DECRYPT_ROUND>, <
uxtb T0, $1
ldr $5, [TABLE, T0, lsl #2]
uxtb T0, $2
ldr $6, [TABLE, T0, lsl #2]
uxtb T0, $3
ldr $7, [TABLE, T0, lsl #2]
uxtb T0, $4
ldr $8, [TABLE, T0, lsl #2]
uxtb T0, $4, ror #8
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $1, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $2, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $3, ror #8
ldr T0, [TABLE, T0, lsl #2]
eor $8, $8, T0
uxtb T0, $3, ror #16
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $4, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $1, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $2, ror #16
ldr T0, [TABLE, T0, lsl #2]
eor $8, $8, T0
uxtb T0, $2, ror #24
add TABLE, TABLE, #1024
ldr T0, [TABLE, T0, lsl #2]
eor $5, $5, T0
uxtb T0, $3, ror #24
ldr T0, [TABLE, T0, lsl #2]
eor $6, $6, T0
uxtb T0, $4, ror #24
ldr T0, [TABLE, T0, lsl #2]
eor $7, $7, T0
uxtb T0, $1, ror #24
ldr T0, [TABLE, T0, lsl #2]
ldm $9!, {$1,$2,$3,$4}
eor $8, $8, T0
sub TABLE, TABLE, #3072
eor $5, $5, $1
eor $6, $6, $2
eor $7, $7, $3
eor $8, $8, $4
>)
.file "aes-decrypt-internal.asm"
C _aes_decrypt(unsigned rounds, const uint32_t *keys,
C const struct aes_table *T,
C size_t length, uint8_t *dst,
C uint8_t *src)
.text
ALIGN(4)
PROLOGUE(_nettle_aes_decrypt)
teq LENGTH, #0
beq .Lend
ldr SRC, [sp, #+4]
push {r0,r1, r4,r5,r6,r7,r8,r10,r11,lr}
ALIGN(16)
.Lblock_loop:
ldm sp, {COUNT, KEY}
add TABLE, TABLE, #AES_TABLE0
AES_LOAD(SRC,KEY,W0)
AES_LOAD(SRC,KEY,W1)
AES_LOAD(SRC,KEY,W2)
AES_LOAD(SRC,KEY,W3)
str SRC, FRAME_SRC
b .Lentry
ALIGN(16)
.Lround_loop:
C Transform X -> W
AES_DECRYPT_ROUND(X0, X1, X2, X3, W0, W1, W2, W3, KEY)
.Lentry:
subs COUNT, COUNT,#2
C Transform W -> X
AES_DECRYPT_ROUND(W0, W1, W2, W3, X0, X1, X2, X3, KEY)
bne .Lround_loop
sub TABLE, TABLE, #AES_TABLE0
C Final round
ldr DST, FRAME_DST
AES_FINAL_ROUND_V6(X0, X3, X2, X1, KEY, W0)
AES_FINAL_ROUND_V6(X1, X0, X3, X2, KEY, W1)
AES_FINAL_ROUND_V6(X2, X1, X0, X3, KEY, W2)
AES_FINAL_ROUND_V6(X3, X2, X1, X0, KEY, W3)
ldr SRC, FRAME_SRC
AES_STORE(DST,W0)
AES_STORE(DST,W1)
AES_STORE(DST,W2)
AES_STORE(DST,W3)
str DST, FRAME_DST
subs LENGTH, LENGTH, #16
bhi .Lblock_loop
add sp, sp, #8 C Drop saved r0, r1
pop {r4,r5,r6,r7,r8,r10,r11,pc}
.Lend:
bx lr
EPILOGUE(_nettle_aes_decrypt)
|
