aes.asm 8.92 KB
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! -*- mode: asm; asm-comment-char: ?!; -*-  
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! nettle, low-level cryptographics library
! 
! Copyright (C) 2002 Niels Mller
!  
! The nettle library is free software; you can redistribute it and/or modify
! it under the terms of the GNU Lesser General Public License as published by
! the Free Software Foundation; either version 2.1 of the License, or (at your
! option) any later version.
! 
! The nettle library 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 Lesser General Public
! License for more details.
! 
! You should have received a copy of the GNU Lesser General Public License
! along with the nettle library; see the file COPYING.LIB.  If not, write to
! the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
! MA 02111-1307, USA.

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! NOTE: Some of the %g registers are reserved for operating system etc
! (see gcc/config/sparc.h). We should use only %g1-%g3 to be safe.
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	! Used registers:	%l0,1,2,3,4,5,6,7
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	!			%i0,1,2,3,4,5 (%i6=%fp, %i7 = return)
	!			%o0,1,2,3,4,5,7 (%o6=%sp)
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	!			%g1,2,3
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	.file	"aes.asm"
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	.section	".text"
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	.align 16
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	.global _aes_crypt
	.type	_aes_crypt,#function
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	.proc	020
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! Arguments
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define(ctx, %i0)
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define(T, %i1)
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define(length, %i2)
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define(dst, %i3)
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define(src, %i4)
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! Loop invariants
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! NOTE: We overwrite %fp with the wtxt pointer,
!       so it must be restored at the end of the function.
define(wtxt, %fp)
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define(tmp, %l1)
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define(diff, %l2)
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define(nrounds, %l3)
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! Loop variables
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define(round, %l4)
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define(i, %l5)
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define(key, %o4)
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! Further loop invariants
define(T0, %l6)
define(T1, %l7)
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define(T2, %l0)
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define(T3, %o7)
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define(IDX1, %i5)
define(IDX3, %o5)
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! Teporaries
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define(t0, %o0)
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define(t1, %o1)
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define(t2, %o2)
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define(t3, %o3)

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C The stack frame looks like
C
C %fp -   4: OS-dependent link field
C %fp -   8: OS-dependent link field
C %fp -  24: tmp, uint32_t[4]
C %fp -  40: wtxt, uint32_t[4]
C %fp - 136: OS register save area. 
define(<FRAME_SIZE>, 136)
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_aes_crypt:
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	save	%sp, -FRAME_SIZE, %sp
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	cmp	length, 0
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	be	.Lend
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	add	%fp, -24, tmp
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	C NOTE: Over writes %fp
	add	%fp, -40, wtxt
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	ld	[ctx + AES_NROUNDS], nrounds
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	! Compute xor, so that we can swap efficiently.
	xor	wtxt, tmp, diff
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	! The loop variable will be multiplied by 16.
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	! More loop invariants
	add	T, AES_TABLE0, T0
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	add	T, AES_TABLE1, T1
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	add	T, AES_TABLE2, T2
	add	T, AES_TABLE3, T3
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	add	T, AES_SIDX1, IDX1
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	add	T, AES_SIDX3, IDX3
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	! Read src, and add initial subkey
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	! Difference between ctx and src.
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	! NOTE: These instructions are duplicated in the delay slot,
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	! and the instruction before the branch
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	sub	ctx, src, %g2
	! Difference between wtxt and src
	sub	wtxt, src, %g3
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.Lblock_loop:
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	! For stop condition. Note that src is incremented in the
	! delay slot
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	add	src, 8, %g1
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.Lsource_loop:
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	ldub	[src+3], t3
	ldub	[src+2], t2
	sll	t3, 24, t3
	ldub	[src+1], t1
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	sll	t2, 16, t2
	or	t3, t2, t3
	ldub	[src], t0
	sll	t1, 8, t1
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	! Get subkey
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	ld	[src+%g2], t2
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	or	t3, t1, t3
	or	t3, t0, t3
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	xor	t3, t2, t3
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	cmp	src, %g1
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	st	t3, [src+%g3]
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	bleu	.Lsource_loop
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	add	src, 4, src
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	sub	nrounds, 1, round
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	add	ctx, 16, key
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	nop
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	! 4*i
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	! NOTE: Instruction duplicated in delay slot
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	mov	0, i
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.Linner_loop:
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	! The comments mark which j in T->table[j][ Bj(wtxt[IDXi(i)]) ]
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	! the instruction is a part of. 
	!
	! The code uses the register %o[j], aka tj, as the primary 
	! register for that sub-expression. True for j==1,3.
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	ld	[IDX1+i], t1		! 1
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	! IDX2(j) = j XOR 2
	xor	i, 8, t2
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	add	wtxt, t1, t1		! 1
	ldub	[t1+2], t1		! 1
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	ld	[IDX3+i], t3		! 3
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	sll	t1, 2, t1		! 1
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	ld	[wtxt+i], t0		! 0
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	lduh	[wtxt+t2], t2		! 2
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	and	t0, 255, t0		! 0
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	ldub	[wtxt+t3], t3		! 3
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	sll	t0, 2, t0		! 0
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	ld	[T0+t0], t0		! 0
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	and	t2, 255, t2		! 2
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	ld	[T1+t1], t1		! 1
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	sll	t2, 2, t2		! 2
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	ld	[T2+t2], t2		! 2
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	sll	t3, 2, t3		! 3
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	ld	[T3+t3], t3		! 3
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	xor	t0, t1, t0		! 0, 1
	xor	t0, t2, t0		! 0, 1, 2
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	! Fetch roundkey
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	ld	[key+i], t1
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	xor	t0, t3, t0		! 0, 1, 2, 3
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	xor	t0, t1, t0
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	st	t0, [tmp+i]
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	cmp	i, 8
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	bleu	.Linner_loop
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	add	i, 4, i
	! switch roles for tmp and wtxt
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	xor	wtxt, diff, wtxt
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	xor	tmp, diff, tmp
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	subcc	round, 1, round
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	add	key, 16, key
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	bne	.Linner_loop
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	mov	0, i
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	! final round
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	! Use round as the loop variable, as it's already zero
undefine(<i>)
define(i, round)
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	! Comments mark which j in T->sbox[Bj(wtxt[IDXj(i)])]
	! the instruction is part of
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	! NOTE: First instruction duplicated in delay slot
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	ld	[IDX1+i], t1 	! 1
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.Lfinal_loop:
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	! IDX2(j) = j XOR 2
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	xor	i, 8, t2
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	add	wtxt, t1, t1	! 1
	ldub	[t1+2], t1	! 1
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	ld	[wtxt+i], t0	! 0
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	lduh	[wtxt+t2], t2	! 2
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	and	t0, 255, t0	! 0
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	ld	[IDX3 + i], t3	! 3
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	and	t2, 255, t2	! 2
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	ldub	[T+t1], t1	! 1
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	ldub	[T+t0], t0	! 0
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	sll	t1, 8, t1	! 1
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	ldub	[wtxt+t3], t3	! 3
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	or	t0, t1, t0	! 0, 1
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	ldub	[T+t2], t2	! 2
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	ldub	[T+t3], t3	! 3
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	sll	t2, 16, t2	! 2
	or	t0, t2, t0	! 0, 1, 2
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	ld	[key + i], t2
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	sll	t3, 24, t3	! 3
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	or	t0, t3, t0	! 0, 1, 2, 3
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	xor	t0, t2, t0
	add	i, 4, i
	cmp	i, 12
	
	srl	t0, 24, t3
	srl	t0, 16, t2
	srl	t0, 8, t1
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	stb	t1, [dst+1]
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	stb	t3, [dst+3]
	stb	t2, [dst+2]
	stb	t0, [dst]
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	add	dst, 4, dst
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	bleu	.Lfinal_loop
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	ld	[IDX1+i], t1 	! 1
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	addcc	length, -16, length
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	sub	ctx, src, %g2
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	bne	.Lblock_loop
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	sub	wtxt, src, %g3
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	add	%sp, FRAME_SIZE, %fp
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.Lend:
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	ret
	restore
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.LLFE1:
.LLfe1:
	.size	_aes_crypt,.LLfe1-_aes_crypt

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	! Benchmarks on my slow sparcstation:	
	! Original C code	
	! aes128 (ECB encrypt): 14.36s, 0.696MB/s
	! aes128 (ECB decrypt): 17.19s, 0.582MB/s
	! aes128 (CBC encrypt): 16.08s, 0.622MB/s
	! aes128 ((CBC decrypt)): 18.79s, 0.532MB/s
	! 
	! aes192 (ECB encrypt): 16.85s, 0.593MB/s
	! aes192 (ECB decrypt): 19.64s, 0.509MB/s
	! aes192 (CBC encrypt): 18.43s, 0.543MB/s
	! aes192 (CBC decrypt): 20.76s, 0.482MB/s
	! 
	! aes256 (ECB encrypt): 19.12s, 0.523MB/s
	! aes256 (ECB decrypt): 22.57s, 0.443MB/s
	! aes256 (CBC encrypt): 20.92s, 0.478MB/s
	! aes256 (CBC decrypt): 23.22s, 0.431MB/s

	! After unrolling key_addition32, and getting rid of
	! some sll x, 2, x, encryption speed is 0.760 MB/s.

	! Next, the C code was optimized to use larger tables and
	! no rotates. New timings:
	! aes128 (ECB encrypt): 13.10s, 0.763MB/s
	! aes128 (ECB decrypt): 11.51s, 0.869MB/s
	! aes128 (CBC encrypt): 15.15s, 0.660MB/s
	! aes128 (CBC decrypt): 13.10s, 0.763MB/s
	! 
	! aes192 (ECB encrypt): 15.68s, 0.638MB/s
	! aes192 (ECB decrypt): 13.59s, 0.736MB/s
	! aes192 (CBC encrypt): 17.65s, 0.567MB/s
	! aes192 (CBC decrypt): 15.31s, 0.653MB/s
	! 
	! aes256 (ECB encrypt): 17.95s, 0.557MB/s
	! aes256 (ECB decrypt): 15.90s, 0.629MB/s
	! aes256 (CBC encrypt): 20.16s, 0.496MB/s
	! aes256 (CBC decrypt): 17.47s, 0.572MB/s

	! After optimization using pre-shifted indices
	! (AES_SIDX[1-3]): 
	! aes128 (ECB encrypt): 12.46s, 0.803MB/s
	! aes128 (ECB decrypt): 10.74s, 0.931MB/s
	! aes128 (CBC encrypt): 17.74s, 0.564MB/s
	! aes128 (CBC decrypt): 12.43s, 0.805MB/s
	! 
	! aes192 (ECB encrypt): 14.59s, 0.685MB/s
	! aes192 (ECB decrypt): 12.76s, 0.784MB/s
	! aes192 (CBC encrypt): 19.97s, 0.501MB/s
	! aes192 (CBC decrypt): 14.46s, 0.692MB/s
	! 
	! aes256 (ECB encrypt): 17.00s, 0.588MB/s
	! aes256 (ECB decrypt): 14.81s, 0.675MB/s
	! aes256 (CBC encrypt): 22.65s, 0.442MB/s
	! aes256 (CBC decrypt): 16.46s, 0.608MB/s
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	! After implementing double buffering
	! aes128 (ECB encrypt): 12.59s, 0.794MB/s
	! aes128 (ECB decrypt): 10.56s, 0.947MB/s
	! aes128 (CBC encrypt): 17.91s, 0.558MB/s
	! aes128 (CBC decrypt): 12.30s, 0.813MB/s
	! 
	! aes192 (ECB encrypt): 15.03s, 0.665MB/s
	! aes192 (ECB decrypt): 12.56s, 0.796MB/s
	! aes192 (CBC encrypt): 20.30s, 0.493MB/s
	! aes192 (CBC decrypt): 14.26s, 0.701MB/s
	! 
	! aes256 (ECB encrypt): 17.30s, 0.578MB/s
	! aes256 (ECB decrypt): 14.51s, 0.689MB/s
	! aes256 (CBC encrypt): 22.75s, 0.440MB/s
	! aes256 (CBC decrypt): 16.35s, 0.612MB/s
	
	! After reordering aes-encrypt.c and aes-decypt.c
	! (the order probably causes strange cache-effects):
	! aes128 (ECB encrypt): 9.21s, 1.086MB/s
	! aes128 (ECB decrypt): 11.13s, 0.898MB/s
	! aes128 (CBC encrypt): 14.12s, 0.708MB/s
	! aes128 (CBC decrypt): 13.77s, 0.726MB/s
	! 
	! aes192 (ECB encrypt): 10.86s, 0.921MB/s
	! aes192 (ECB decrypt): 13.17s, 0.759MB/s
	! aes192 (CBC encrypt): 15.74s, 0.635MB/s
	! aes192 (CBC decrypt): 15.91s, 0.629MB/s
	! 
	! aes256 (ECB encrypt): 12.71s, 0.787MB/s
	! aes256 (ECB decrypt): 15.38s, 0.650MB/s
	! aes256 (CBC encrypt): 17.49s, 0.572MB/s
	! aes256 (CBC decrypt): 17.87s, 0.560MB/s
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	! After further optimizations of the initial and final loops,
	! source_loop and final_loop. 
	! aes128 (ECB encrypt): 8.07s, 1.239MB/s
	! aes128 (ECB decrypt): 9.48s, 1.055MB/s
	! aes128 (CBC encrypt): 12.76s, 0.784MB/s
	! aes128 (CBC decrypt): 12.15s, 0.823MB/s
	! 
	! aes192 (ECB encrypt): 9.43s, 1.060MB/s
	! aes192 (ECB decrypt): 11.20s, 0.893MB/s
	! aes192 (CBC encrypt): 14.19s, 0.705MB/s
	! aes192 (CBC decrypt): 13.97s, 0.716MB/s
	! 
	! aes256 (ECB encrypt): 10.81s, 0.925MB/s
	! aes256 (ECB decrypt): 12.92s, 0.774MB/s
	! aes256 (CBC encrypt): 15.59s, 0.641MB/s
	! aes256 (CBC decrypt): 15.76s, 0.635MB/s