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1 | /* |
2 | * Copyright (c) 2019 Arm Limited | |
3 | * | |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
5 | * you may not use this file except in compliance with the License. | |
6 | * You may obtain a copy of the License at: | |
7 | * | |
8 | * http://www.apache.org/licenses/LICENSE-2.0 | |
9 | * | |
10 | * Unless required by applicable law or agreed to in writing, software | |
11 | * distributed under the License is distributed on an "AS IS" BASIS, | |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
13 | * See the License for the specific language governing permissions and | |
14 | * limitations under the License. | |
15 | */ | |
16 | ||
17 | /* This header implements HASH operation primitives on aarch64. */ | |
18 | #ifndef HASH_AARCH64_H | |
19 | #define HASH_AARCH64_H 1 | |
20 | ||
21 | #ifndef HASH_H | |
22 | #error "This header should only be included indirectly via hash.h." | |
23 | #endif | |
24 | ||
25 | #ifdef __cplusplus | |
26 | extern "C" { | |
27 | #endif | |
28 | ||
29 | #include <arm_acle.h> | |
30 | ||
31 | static inline uint32_t hash_add(uint32_t hash, uint32_t data) | |
32 | { | |
33 | return __crc32cw(hash, data); | |
34 | } | |
35 | ||
36 | /* Add the halves of 'data' in the memory order. */ | |
37 | static inline uint32_t hash_add64(uint32_t hash, uint64_t data) | |
38 | { | |
39 | return __crc32cd(hash, data); | |
40 | } | |
41 | ||
42 | static inline uint32_t hash_finish(uint32_t hash, uint64_t final) | |
43 | { | |
44 | /* The finishing multiplier 0x805204f3 has been experimentally | |
45 | * derived to pass the testsuite hash tests. */ | |
46 | hash = __crc32cd(hash, final) * 0x805204f3; | |
47 | return hash ^ hash >> 16; /* Increase entropy in LSBs. */ | |
48 | } | |
49 | ||
50 | /* Returns the hash of the 'n' 32-bit words at 'p_', starting from 'basis'. | |
51 | * We access 'p_' as a uint64_t pointer. | |
52 | * | |
53 | * This is inlined for the compiler to have access to the 'n_words', which | |
54 | * in many cases is a constant. */ | |
55 | static inline uint32_t | |
56 | hash_words_inline(const uint32_t p_[], size_t n_words, uint32_t basis) | |
57 | { | |
58 | const uint64_t *p = (const void *)p_; | |
59 | uint32_t hash1 = basis; | |
60 | uint32_t hash2 = 0; | |
61 | uint32_t hash3 = n_words; | |
62 | const uint32_t *endp = (const uint32_t *)p + n_words; | |
63 | const uint64_t *limit = p + n_words / 2 - 3; | |
64 | ||
65 | while (p <= limit) { | |
66 | hash1 = __crc32cd(hash1, p[0]); | |
67 | hash2 = __crc32cd(hash2, p[1]); | |
68 | hash3 = __crc32cd(hash3, p[2]); | |
69 | p += 3; | |
70 | } | |
71 | switch (endp - (const uint32_t *)p) { | |
72 | case 1: | |
73 | hash1 = __crc32cw(hash1, *(const uint32_t *)&p[0]); | |
74 | break; | |
75 | case 2: | |
76 | hash1 = __crc32cd(hash1, p[0]); | |
77 | break; | |
78 | case 3: | |
79 | hash1 = __crc32cd(hash1, p[0]); | |
80 | hash2 = __crc32cw(hash2, *(const uint32_t *)&p[1]); | |
81 | break; | |
82 | case 4: | |
83 | hash1 = __crc32cd(hash1, p[0]); | |
84 | hash2 = __crc32cd(hash2, p[1]); | |
85 | break; | |
86 | case 5: | |
87 | hash1 = __crc32cd(hash1, p[0]); | |
88 | hash2 = __crc32cd(hash2, p[1]); | |
89 | hash3 = __crc32cw(hash3, *(const uint32_t *)&p[2]); | |
90 | break; | |
91 | } | |
92 | return hash_finish(hash1, (uint64_t)hash2 << 32 | hash3); | |
93 | } | |
94 | ||
95 | /* A simpler version for 64-bit data. | |
96 | * 'n_words' is the count of 64-bit words, basis is 64 bits. */ | |
97 | static inline uint32_t | |
98 | hash_words64_inline(const uint64_t p[], size_t n_words, uint32_t basis) | |
99 | { | |
100 | uint32_t hash1 = basis; | |
101 | uint32_t hash2 = 0; | |
102 | uint32_t hash3 = n_words; | |
103 | const uint64_t *endp = p + n_words; | |
104 | const uint64_t *limit = endp - 3; | |
105 | ||
106 | while (p <= limit) { | |
107 | hash1 = __crc32cd(hash1, p[0]); | |
108 | hash2 = __crc32cd(hash2, p[1]); | |
109 | hash3 = __crc32cd(hash3, p[2]); | |
110 | p += 3; | |
111 | } | |
112 | switch (endp - p) { | |
113 | case 1: | |
114 | hash1 = __crc32cd(hash1, p[0]); | |
115 | break; | |
116 | case 2: | |
117 | hash1 = __crc32cd(hash1, p[0]); | |
118 | hash2 = __crc32cd(hash2, p[1]); | |
119 | break; | |
120 | } | |
121 | return hash_finish(hash1, (uint64_t)hash2 << 32 | hash3); | |
122 | } | |
123 | ||
124 | static inline uint32_t hash_uint64_basis(const uint64_t x, | |
125 | const uint32_t basis) | |
126 | { | |
127 | /* '23' chosen to mix bits enough for the test-hash to pass. */ | |
128 | return hash_finish(hash_add64(basis, x), 23); | |
129 | } | |
130 | ||
131 | static inline uint32_t hash_uint64(const uint64_t x) | |
132 | { | |
133 | return hash_uint64_basis(x, 0); | |
134 | } | |
135 | ||
136 | static inline uint32_t hash_2words(uint32_t x, uint32_t y) | |
137 | { | |
138 | return hash_uint64((uint64_t)y << 32 | x); | |
139 | } | |
140 | ||
141 | static inline uint32_t hash_pointer(const void *p, uint32_t basis) | |
142 | { | |
143 | return hash_uint64_basis((uint64_t) (uintptr_t) p, basis); | |
144 | } | |
145 | ||
146 | #ifdef __cplusplus | |
147 | } | |
148 | #endif | |
149 | ||
150 | #endif /* hash-aarch64.h */ |