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1 | /// -*- mode: asm; asm-comment-char: ?/ -*- |
2 | /// | |
3 | /// Fancy SIMD implementation of ChaCha for ARM | |
4 | /// | |
5 | /// (c) 2016 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 | ///-------------------------------------------------------------------------- | |
df07f2c0 | 28 | /// Preliminaries. |
704d59c8 MW |
29 | |
30 | #include "config.h" | |
31 | #include "asm-common.h" | |
32 | ||
704d59c8 MW |
33 | .arch armv7-a |
34 | .fpu neon | |
df07f2c0 | 35 | |
bc9ac7eb | 36 | .text |
704d59c8 | 37 | |
df07f2c0 MW |
38 | ///-------------------------------------------------------------------------- |
39 | /// Main.code. | |
40 | ||
704d59c8 MW |
41 | FUNC(chacha_core_arm_neon) |
42 | ||
43 | // Arguments are in registers. | |
44 | // r0 is the number of rounds to perform | |
45 | // r1 points to the input matrix | |
46 | // r2 points to the output matrix | |
47 | ||
48 | // First job is to slurp the matrix into the SIMD registers. vldm | |
49 | // and vstm work on word-aligned data, so this is fine. | |
50 | // | |
51 | // [ 0 1 2 3] (a, q8) | |
52 | // [ 4 5 6 7] (b, q9) | |
53 | // [ 8 9 10 11] (c, q10) | |
54 | // [12 13 14 15] (d, q11) | |
55 | // | |
56 | // We need a copy for later. Rather than waste time copying them by | |
57 | // hand, we'll use the three-address nature of the instruction set. | |
58 | // But this means that the main loop is offset by a bit. | |
43ea7558 | 59 | vldmia r1, {QQ(q12, q15)} |
704d59c8 MW |
60 | |
61 | // a += b; d ^= a; d <<<= 16 | |
62 | vadd.u32 q8, q12, q13 | |
63 | veor q11, q15, q8 | |
64 | vshl.u32 q0, q11, #16 | |
65 | vshr.u32 q11, q11, #16 | |
66 | vorr q11, q11, q0 | |
67 | ||
68 | // c += d; b ^= c; b <<<= 12 | |
69 | vadd.u32 q10, q14, q11 | |
70 | veor q9, q13, q10 | |
71 | vshl.u32 q0, q9, #12 | |
72 | vshr.u32 q9, q9, #20 | |
73 | vorr q9, q9, q0 | |
74 | ||
75 | 0: | |
76 | // Apply (the rest of) a column quarterround to each of the columns | |
77 | // simultaneously. Alas, there doesn't seem to be a packed word | |
78 | // rotate, so we have to synthesize it. | |
79 | ||
80 | // a += b; d ^= a; d <<<= 8 | |
81 | vadd.u32 q8, q8, q9 | |
82 | veor q11, q11, q8 | |
83 | vshl.u32 q0, q11, #8 | |
84 | vshr.u32 q11, q11, #24 | |
85 | vorr q11, q11, q0 | |
86 | ||
87 | // c += d; b ^= c; b <<<= 7 | |
88 | vadd.u32 q10, q10, q11 | |
70bc6059 | 89 | vext.32 q11, q11, q11, #3 |
704d59c8 | 90 | veor q9, q9, q10 |
70bc6059 | 91 | vext.32 q10, q10, q10, #2 |
704d59c8 MW |
92 | vshl.u32 q0, q9, #7 |
93 | vshr.u32 q9, q9, #25 | |
94 | vorr q9, q9, q0 | |
95 | ||
96 | // The not-quite-transpose conveniently only involves reordering | |
97 | // elements of individual rows, which can be done quite easily. It | |
98 | // doesn't involve any movement of elements between rows, or even | |
99 | // renaming of the rows. | |
100 | // | |
101 | // [ 0 1 2 3] [ 0 1 2 3] (a, q8) | |
102 | // [ 4 5 6 7] --> [ 5 6 7 4] (b, q9) | |
103 | // [ 8 9 10 11] [10 11 8 9] (c, q10) | |
104 | // [12 13 14 15] [15 12 13 14] (d, q11) | |
105 | // | |
106 | // The reorderings have for the most part been pushed upwards to | |
107 | // reduce delays. | |
108 | vext.32 q9, q9, q9, #1 | |
109 | ||
110 | // Apply the diagonal quarterround to each of the columns | |
111 | // simultaneously. | |
112 | ||
113 | // a += b; d ^= a; d <<<= 16 | |
114 | vadd.u32 q8, q8, q9 | |
115 | veor q11, q11, q8 | |
116 | vshl.u32 q0, q11, #16 | |
117 | vshr.u32 q11, q11, #16 | |
118 | vorr q11, q11, q0 | |
119 | ||
120 | // c += d; b ^= c; b <<<= 12 | |
121 | vadd.u32 q10, q10, q11 | |
122 | veor q9, q9, q10 | |
123 | vshl.u32 q0, q9, #12 | |
124 | vshr.u32 q9, q9, #20 | |
125 | vorr q9, q9, q0 | |
126 | ||
127 | // a += b; d ^= a; d <<<= 8 | |
128 | vadd.u32 q8, q8, q9 | |
129 | veor q11, q11, q8 | |
130 | vshl.u32 q0, q11, #8 | |
131 | vshr.u32 q11, q11, #24 | |
132 | vorr q11, q11, q0 | |
133 | ||
134 | // c += d; b ^= c; b <<<= 7 | |
135 | vadd.u32 q10, q10, q11 | |
70bc6059 | 136 | vext.32 q11, q11, q11, #1 |
704d59c8 | 137 | veor q9, q9, q10 |
70bc6059 | 138 | vext.32 q10, q10, q10, #2 |
704d59c8 MW |
139 | vshl.u32 q0, q9, #7 |
140 | vshr.u32 q9, q9, #25 | |
141 | vorr q9, q9, q0 | |
142 | ||
143 | // Finally finish off undoing the transpose, and we're done for this | |
144 | // doubleround. Again, most of this was done above so we don't have | |
145 | // to wait for the reorderings. | |
146 | vext.32 q9, q9, q9, #3 | |
147 | ||
148 | // Decrement the loop counter and see if we should go round again. | |
149 | subs r0, r0, #2 | |
150 | bls 9f | |
151 | ||
152 | // Do the first part of the next round because this loop is offset. | |
153 | ||
154 | // a += b; d ^= a; d <<<= 16 | |
155 | vadd.u32 q8, q8, q9 | |
156 | veor q11, q11, q8 | |
157 | vshl.u32 q0, q11, #16 | |
158 | vshr.u32 q11, q11, #16 | |
159 | vorr q11, q11, q0 | |
160 | ||
161 | // c += d; b ^= c; b <<<= 12 | |
162 | vadd.u32 q10, q10, q11 | |
163 | veor q9, q9, q10 | |
164 | vshl.u32 q0, q9, #12 | |
165 | vshr.u32 q9, q9, #20 | |
166 | vorr q9, q9, q0 | |
167 | ||
168 | b 0b | |
169 | ||
170 | // Almost there. Firstly the feedfoward addition. | |
171 | 9: vadd.u32 q8, q8, q12 | |
172 | vadd.u32 q9, q9, q13 | |
173 | vadd.u32 q10, q10, q14 | |
174 | vadd.u32 q11, q11, q15 | |
175 | ||
176 | // And now we write out the result. | |
43ea7558 | 177 | vstmia r2, {QQ(q8, q11)} |
704d59c8 MW |
178 | |
179 | // And with that, we're done. | |
180 | bx r14 | |
181 | ||
182 | ENDFUNC | |
183 | ||
184 | ///----- That's all, folks -------------------------------------------------- |