mdw@git.distorted.org.uk Git - catacomb/blob - symm/chacha-x86-sse2.S

   1 /// -*- mode: asm; asm-comment-char: ?/ -*-
   2 ///
   3 /// Fancy SIMD implementation of ChaCha
   4 ///
   5 /// (c) 2015 Straylight/Edgeware
   6 ///
   7
   8 ///----- Licensing notice ---------------------------------------------------
   9 ///
  10 /// This file is part of Catacomb.
  11 ///
  12 /// Catacomb is free software; you can redistribute it and/or modify
  13 /// it under the terms of the GNU Library General Public License as
  14 /// published by the Free Software Foundation; either version 2 of the
  15 /// License, or (at your option) any later version.
  16 ///
  17 /// Catacomb is distributed in the hope that it will be useful,
  18 /// but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 /// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 /// GNU Library General Public License for more details.
  21 ///
  22 /// You should have received a copy of the GNU Library General Public
  23 /// License along with Catacomb; if not, write to the Free
  24 /// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  25 /// MA 02111-1307, USA.
  26
  27 ///--------------------------------------------------------------------------
  28 /// External definitions.
  29
  30 #include "config.h"
  31 #include "asm-common.h"
  32
  33 ///--------------------------------------------------------------------------
  34 /// Local utilities.
  35
  36 // Magic constants for shuffling.
  37 #define ROTL 0x93
  38 #define ROT2 0x4e
  39 #define ROTR 0x39
  40
  41 ///--------------------------------------------------------------------------
  42 /// Main code.
  43
  44         .arch pentium4
  45         .section .text
  46
  47 FUNC(chacha_core_x86_sse2)
  48
  49         // Initial state.  We have three arguments:
  50         // [ebp +  8] is the number of rounds to do
  51         // [ebp + 12] points to the input matrix
  52         // [ebp + 16] points to the output matrix
  53         push    ebp
  54         mov     ebp, esp
  55         sub     esp, 16
  56         mov     edx, [ebp + 12]
  57         and     esp, ~15
  58
  59         // First job is to slurp the matrix into XMM registers.  Be careful:
  60         // the input matrix isn't likely to be properly aligned.
  61         //
  62         //      [ 0  1  2  3] (a, xmm0)
  63         //      [ 4  5  6  7] (b, xmm1)
  64         //      [ 8  9 10 11] (c, xmm2)
  65         //      [12 13 14 15] (d, xmm3)
  66         movdqu  xmm0, [edx +  0]
  67         movdqu  xmm1, [edx + 16]
  68         movdqu  xmm2, [edx + 32]
  69         movdqu  xmm3, [edx + 48]
  70
  71         // Prepare for the main loop.
  72         mov     ecx, [ebp + 8]
  73
  74         // Take a copy for later.  This one is aligned properly, by
  75         // construction.
  76         movdqa  [esp], xmm0
  77         movdqa  xmm5, xmm1
  78         movdqa  xmm6, xmm2
  79         movdqa  xmm7, xmm3
  80
  81 loop:
  82         // Apply a column quarterround to each of the columns simultaneously.
  83         // Alas, there doesn't seem to be a packed doubleword rotate, so we
  84         // have to synthesize it.
  85
  86         // a += b; d ^= a; d <<<= 16
  87         paddd   xmm0, xmm1
  88         pxor    xmm3, xmm0
  89         movdqa  xmm4, xmm3
  90         pslld   xmm3, 16
  91         psrld   xmm4, 16
  92         por     xmm3, xmm4
  93
  94         // c += d; b ^= c; b <<<= 12
  95         paddd   xmm2, xmm3
  96         pxor    xmm1, xmm2
  97         movdqa  xmm4, xmm1
  98         pslld   xmm1, 12
  99         psrld   xmm4, 20
 100         por     xmm1, xmm4
 101
 102         // a += b; d ^= a; d <<<=  8
 103         paddd   xmm0, xmm1
 104         pxor    xmm3, xmm0
 105         movdqa  xmm4, xmm3
 106         pslld   xmm3, 8
 107         psrld   xmm4, 24
 108         por     xmm3, xmm4
 109
 110         // c += d; b ^= c; b <<<=  7
 111         paddd   xmm2, xmm3
 112         pshufd  xmm3, xmm3, ROTL
 113         pxor    xmm1, xmm2
 114         pshufd  xmm2, xmm2, ROT2
 115         movdqa  xmm4, xmm1
 116         pslld   xmm1, 7
 117         psrld   xmm4, 25
 118         por     xmm1, xmm4
 119
 120         // The not-quite-transpose conveniently only involves reordering
 121         // elements of individual rows, which can be done quite easily.  It
 122         // doesn't involve any movement of elements between rows, or even
 123         // renaming of the rows.
 124         //
 125         //      [ 0  1  2  3]           [ 0  1  2  3] (a, xmm0)
 126         //      [ 4  5  6  7]    -->    [ 5  6  7  4] (b, xmm1)
 127         //      [ 8  9 10 11]           [10 11  8  9] (c, xmm2)
 128         //      [12 13 14 15]           [15 12 13 14] (d, xmm3)
 129         //
 130         // The shuffles have quite high latency, so they've mostly been
 131         // pushed upwards.  The remaining one can't be moved, though.
 132         pshufd  xmm1, xmm1, ROTR
 133
 134         // Apply the diagonal quarterround to each of the columns
 135         // simultaneously.
 136
 137         // a += b; d ^= a; d <<<= 16
 138         paddd   xmm0, xmm1
 139         pxor    xmm3, xmm0
 140         movdqa  xmm4, xmm3
 141         pslld   xmm3, 16
 142         psrld   xmm4, 16
 143         por     xmm3, xmm4
 144
 145         // c += d; b ^= c; b <<<= 12
 146         paddd   xmm2, xmm3
 147         pxor    xmm1, xmm2
 148         movdqa  xmm4, xmm1
 149         pslld   xmm1, 12
 150         psrld   xmm4, 20
 151         por     xmm1, xmm4
 152
 153         // a += b; d ^= a; d <<<=  8
 154         paddd   xmm0, xmm1
 155         pxor    xmm3, xmm0
 156         movdqa  xmm4, xmm3
 157         pslld   xmm3, 8
 158         psrld   xmm4, 24
 159         por     xmm3, xmm4
 160
 161         // c += d; b ^= c; b <<<=  7
 162         paddd   xmm2, xmm3
 163         pshufd  xmm3, xmm3, ROTR
 164         pxor    xmm1, xmm2
 165         pshufd  xmm2, xmm2, ROT2
 166         movdqa  xmm4, xmm1
 167         pslld   xmm1, 7
 168         psrld   xmm4, 25
 169         por     xmm1, xmm4
 170
 171         // Finally, finish off undoing the transpose, and we're done for this
 172         // doubleround.  Again, most of this was done above so we don't have
 173         // to wait for the shuffles.
 174         pshufd  xmm1, xmm1, ROTL
 175
 176         // Decrement the loop counter and see if we should go round again.
 177         sub     ecx, 2
 178         ja      loop
 179
 180         // Almost there.  Firstly, the feedforward addition.
 181         mov     edx, [ebp + 16]
 182         paddd   xmm0, [esp]
 183         paddd   xmm1, xmm5
 184         paddd   xmm2, xmm6
 185         paddd   xmm3, xmm7
 186
 187         // And now we write out the result.  This one won't be aligned
 188         // either.
 189         movdqu  [edx +  0], xmm0
 190         movdqu  [edx + 16], xmm1
 191         movdqu  [edx + 32], xmm2
 192         movdqu  [edx + 48], xmm3
 193
 194         // Tidy things up.
 195         mov     esp, ebp
 196         pop     ebp
 197
 198         // And with that, we're done.
 199         ret
 200
 201 ENDFUNC
 202
 203 ///----- That's all, folks --------------------------------------------------