2 * Copyright 2016 Ferry Toth, Exalon Delft BV, The Netherlands
3 * This software is provided 'as-is', without any express or implied
4 * warranty. In no event will the author be held liable for any damages
5 * arising from the use of this software.
6 * Permission is granted to anyone to use this software for any purpose,
7 * including commercial applications, and to alter it and redistribute it
8 * freely, subject to the following restrictions:
9 * 1. The origin of this software must not be misrepresented; you must not
10 * claim that you wrote the original software. If you use this software
11 * in a product, an acknowledgment in the product documentation would be
12 * appreciated but is not required.
13 * 2. Altered source versions must be plainly marked as such, and must not be
14 * misrepresented as being the original software.
15 * 3. This notice may not be removed or altered from any source distribution.
17 * ftoth@exalondelft.nl
19 * https://github.com/htot/crc32c
21 * Modified by Facebook
23 * Original intel whitepaper:
24 * "Fast CRC Computation for iSCSI Polynomial Using CRC32 Instruction"
25 * https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/crc-iscsi-polynomial-crc32-instruction-paper.pdf
27 * 32-bit support dropped
28 * use intrinsics instead of inline asm
34 #include <folly/detail/ChecksumDetail.h>
36 #include <folly/CppAttributes.h>
38 #include <boost/preprocessor/arithmetic/add.hpp>
39 #include <boost/preprocessor/arithmetic/sub.hpp>
40 #include <boost/preprocessor/repetition/repeat_from_to.hpp>
43 namespace crc32_detail {
45 #if FOLLY_SSE_PREREQ(4, 2)
47 #define CRCtriplet(crc, buf, offset) \
48 crc##0 = _mm_crc32_u64(crc##0, *(buf##0 + offset)); \
49 crc##1 = _mm_crc32_u64(crc##1, *(buf##1 + offset)); \
50 crc##2 = _mm_crc32_u64(crc##2, *(buf##2 + offset)); \
53 #define CRCduplet(crc, buf, offset) \
54 crc##0 = _mm_crc32_u64(crc##0, *(buf##0 + offset)); \
55 crc##1 = _mm_crc32_u64(crc##1, *(buf##1 + offset));
57 #define CRCsinglet(crc, buf, offset) \
58 crc = _mm_crc32_u64(crc, *(uint64_t*)(buf + offset)); \
61 #define CASEREPEAT_TRIPLET(unused, count, total) \
62 case BOOST_PP_ADD(1, BOOST_PP_SUB(total, count)): \
63 CRCtriplet(crc, next, -BOOST_PP_ADD(1, BOOST_PP_SUB(total, count)));
65 #define CASEREPEAT_SINGLET(unused, count, total) \
66 case BOOST_PP_SUB(total, count): \
67 CRCsinglet(crc0, next, -BOOST_PP_SUB(total, count) * 8);
69 // Numbers taken directly from intel whitepaper.
70 const __m128i clmul_constants[] = {
71 {0x14cd00bd6, 0x105ec76f0}, {0x0ba4fc28e, 0x14cd00bd6},
72 {0x1d82c63da, 0x0f20c0dfe}, {0x09e4addf8, 0x0ba4fc28e},
73 {0x039d3b296, 0x1384aa63a}, {0x102f9b8a2, 0x1d82c63da},
74 {0x14237f5e6, 0x01c291d04}, {0x00d3b6092, 0x09e4addf8},
75 {0x0c96cfdc0, 0x0740eef02}, {0x18266e456, 0x039d3b296},
76 {0x0daece73e, 0x0083a6eec}, {0x0ab7aff2a, 0x102f9b8a2},
77 {0x1248ea574, 0x1c1733996}, {0x083348832, 0x14237f5e6},
78 {0x12c743124, 0x02ad91c30}, {0x0b9e02b86, 0x00d3b6092},
79 {0x018b33a4e, 0x06992cea2}, {0x1b331e26a, 0x0c96cfdc0},
80 {0x17d35ba46, 0x07e908048}, {0x1bf2e8b8a, 0x18266e456},
81 {0x1a3e0968a, 0x11ed1f9d8}, {0x0ce7f39f4, 0x0daece73e},
82 {0x061d82e56, 0x0f1d0f55e}, {0x0d270f1a2, 0x0ab7aff2a},
83 {0x1c3f5f66c, 0x0a87ab8a8}, {0x12ed0daac, 0x1248ea574},
84 {0x065863b64, 0x08462d800}, {0x11eef4f8e, 0x083348832},
85 {0x1ee54f54c, 0x071d111a8}, {0x0b3e32c28, 0x12c743124},
86 {0x0064f7f26, 0x0ffd852c6}, {0x0dd7e3b0c, 0x0b9e02b86},
87 {0x0f285651c, 0x0dcb17aa4}, {0x010746f3c, 0x018b33a4e},
88 {0x1c24afea4, 0x0f37c5aee}, {0x0271d9844, 0x1b331e26a},
89 {0x08e766a0c, 0x06051d5a2}, {0x093a5f730, 0x17d35ba46},
90 {0x06cb08e5c, 0x11d5ca20e}, {0x06b749fb2, 0x1bf2e8b8a},
91 {0x1167f94f2, 0x021f3d99c}, {0x0cec3662e, 0x1a3e0968a},
92 {0x19329634a, 0x08f158014}, {0x0e6fc4e6a, 0x0ce7f39f4},
93 {0x08227bb8a, 0x1a5e82106}, {0x0b0cd4768, 0x061d82e56},
94 {0x13c2b89c4, 0x188815ab2}, {0x0d7a4825c, 0x0d270f1a2},
95 {0x10f5ff2ba, 0x105405f3e}, {0x00167d312, 0x1c3f5f66c},
96 {0x0f6076544, 0x0e9adf796}, {0x026f6a60a, 0x12ed0daac},
97 {0x1a2adb74e, 0x096638b34}, {0x19d34af3a, 0x065863b64},
98 {0x049c3cc9c, 0x1e50585a0}, {0x068bce87a, 0x11eef4f8e},
99 {0x1524fa6c6, 0x19f1c69dc}, {0x16cba8aca, 0x1ee54f54c},
100 {0x042d98888, 0x12913343e}, {0x1329d9f7e, 0x0b3e32c28},
101 {0x1b1c69528, 0x088f25a3a}, {0x02178513a, 0x0064f7f26},
102 {0x0e0ac139e, 0x04e36f0b0}, {0x0170076fa, 0x0dd7e3b0c},
103 {0x141a1a2e2, 0x0bd6f81f8}, {0x16ad828b4, 0x0f285651c},
104 {0x041d17b64, 0x19425cbba}, {0x1fae1cc66, 0x010746f3c},
105 {0x1a75b4b00, 0x18db37e8a}, {0x0f872e54c, 0x1c24afea4},
106 {0x01e41e9fc, 0x04c144932}, {0x086d8e4d2, 0x0271d9844},
107 {0x160f7af7a, 0x052148f02}, {0x05bb8f1bc, 0x08e766a0c},
108 {0x0a90fd27a, 0x0a3c6f37a}, {0x0b3af077a, 0x093a5f730},
109 {0x04984d782, 0x1d22c238e}, {0x0ca6ef3ac, 0x06cb08e5c},
110 {0x0234e0b26, 0x063ded06a}, {0x1d88abd4a, 0x06b749fb2},
111 {0x04597456a, 0x04d56973c}, {0x0e9e28eb4, 0x1167f94f2},
112 {0x07b3ff57a, 0x19385bf2e}, {0x0c9c8b782, 0x0cec3662e},
113 {0x13a9cba9e, 0x0e417f38a}, {0x093e106a4, 0x19329634a},
114 {0x167001a9c, 0x14e727980}, {0x1ddffc5d4, 0x0e6fc4e6a},
115 {0x00df04680, 0x0d104b8fc}, {0x02342001e, 0x08227bb8a},
116 {0x00a2a8d7e, 0x05b397730}, {0x168763fa6, 0x0b0cd4768},
117 {0x1ed5a407a, 0x0e78eb416}, {0x0d2c3ed1a, 0x13c2b89c4},
118 {0x0995a5724, 0x1641378f0}, {0x19b1afbc4, 0x0d7a4825c},
119 {0x109ffedc0, 0x08d96551c}, {0x0f2271e60, 0x10f5ff2ba},
120 {0x00b0bf8ca, 0x00bf80dd2}, {0x123888b7a, 0x00167d312},
121 {0x1e888f7dc, 0x18dcddd1c}, {0x002ee03b2, 0x0f6076544},
122 {0x183e8d8fe, 0x06a45d2b2}, {0x133d7a042, 0x026f6a60a},
123 {0x116b0f50c, 0x1dd3e10e8}, {0x05fabe670, 0x1a2adb74e},
124 {0x130004488, 0x0de87806c}, {0x000bcf5f6, 0x19d34af3a},
125 {0x18f0c7078, 0x014338754}, {0x017f27698, 0x049c3cc9c},
126 {0x058ca5f00, 0x15e3e77ee}, {0x1af900c24, 0x068bce87a},
127 {0x0b5cfca28, 0x0dd07448e}, {0x0ded288f8, 0x1524fa6c6},
128 {0x059f229bc, 0x1d8048348}, {0x06d390dec, 0x16cba8aca},
129 {0x037170390, 0x0a3e3e02c}, {0x06353c1cc, 0x042d98888},
130 {0x0c4584f5c, 0x0d73c7bea}, {0x1f16a3418, 0x1329d9f7e},
131 {0x0531377e2, 0x185137662}, {0x1d8d9ca7c, 0x1b1c69528},
132 {0x0b25b29f2, 0x18a08b5bc}, {0x19fb2a8b0, 0x02178513a},
133 {0x1a08fe6ac, 0x1da758ae0}, {0x045cddf4e, 0x0e0ac139e},
134 {0x1a91647f2, 0x169cf9eb0}, {0x1a0f717c4, 0x0170076fa},
138 * CombineCRC performs pclmulqdq multiplication of 2 partial CRC's and a well
139 * chosen constant and xor's these with the remaining CRC.
142 unsigned long block_size,
146 const uint64_t* next2) {
147 const auto multiplier = *(clmul_constants + block_size - 1);
148 const auto crc0_xmm = _mm_set_epi64x(0, crc0);
149 const auto res0 = _mm_clmulepi64_si128(crc0_xmm, multiplier, 0x00);
150 const auto crc1_xmm = _mm_set_epi64x(0, crc1);
151 const auto res1 = _mm_clmulepi64_si128(crc1_xmm, multiplier, 0x10);
152 const auto res = _mm_xor_si128(res0, res1);
153 crc0 = _mm_cvtsi128_si64(res);
154 crc0 = crc0 ^ *((uint64_t*)next2 - 1);
155 crc2 = _mm_crc32_u64(crc2, crc0);
159 // Generates a block that will crc up to 7 bytes of unaligned data.
160 // Always inline to avoid overhead on small crc sizes.
161 FOLLY_ALWAYS_INLINE void align_to_8(
163 uint64_t& crc0, // crc so far, updated on return
164 const unsigned char*& next) { // next data pointer, updated on return
165 uint32_t crc32bit = crc0;
167 crc32bit = _mm_crc32_u32(crc32bit, *(uint32_t*)next);
168 next += sizeof(uint32_t);
171 crc32bit = _mm_crc32_u16(crc32bit, *(uint16_t*)next);
172 next += sizeof(uint16_t);
175 crc32bit = _mm_crc32_u8(crc32bit, *(next));
181 // The main loop for large crc sizes. Generates three crc32c
182 // streams, of varying block sizes, using a duff's device.
184 unsigned long block_size,
185 uint64_t& crc0, // crc so far, updated on return
186 const unsigned char*& next, // next data pointer, updated on return
187 unsigned long n) { // block count
188 uint64_t crc1 = 0, crc2 = 0;
189 // points to the first byte of the next block
190 const uint64_t* next0 = (uint64_t*)next + block_size;
191 const uint64_t* next1 = next0 + block_size;
192 const uint64_t* next2 = next1 + block_size;
194 // Use Duff's device, a for() loop inside a switch()
195 // statement. This needs to execute at least once, round len
196 // down to nearest triplet multiple
197 switch (block_size) {
200 // jumps here for a full block of len 128
201 CRCtriplet(crc, next, -128);
203 // Generates case statements from 127 to 2 of form:
205 // CRCtriplet(crc, next, -127);
206 BOOST_PP_REPEAT_FROM_TO(0, 126, CASEREPEAT_TRIPLET, 126);
208 // For the last byte, the three crc32c streams must be combined
209 // using carry-less multiplication.
211 CRCduplet(crc, next, -1); // the final triplet is actually only 2
212 crc0 = CombineCRC(block_size, crc0, crc1, crc2, next2);
216 // points to the first byte of the next block
218 next1 = next0 + 128; // from here on all blocks are 128 long
226 next = (const unsigned char*)next2;
229 } // namespace crc32c_detail
233 /* Compute CRC-32C using the Intel hardware instruction. */
234 FOLLY_TARGET_ATTRIBUTE("sse4.2")
235 uint32_t crc32c_hw(const uint8_t* buf, size_t len, uint32_t crc) {
236 const unsigned char* next = (const unsigned char*)buf;
242 // if len > 216 then align and use triplets
244 unsigned long align = (8 - (uintptr_t)next) & 7;
245 crc32_detail::align_to_8(align, crc0, next);
248 count = len / 24; // number of triplets
249 len %= 24; // bytes remaining
250 unsigned long n = count >> 7; // #blocks = first block + full blocks
251 unsigned long block_size = count & 127;
252 if (block_size == 0) {
258 // This is a separate function call mainly to stop
259 // clang from spilling registers.
260 crc32_detail::triplet_loop(block_size, crc0, next, n);
263 unsigned count2 = len >> 3;
265 next += (count2 * 8);
267 // Generates a duff device for the last 128 bytes of aligned data.
269 // Generates case statements of the form:
271 // CRCsinglet(crc0, next, -27 * 8);
272 BOOST_PP_REPEAT_FROM_TO(0, 27, CASEREPEAT_SINGLET, 27);
277 // compute the crc for up to seven trailing bytes
278 crc32_detail::align_to_8(len, crc0, next);
279 return (uint32_t)crc0;
285 crc32c_hw(const uint8_t* data, size_t nbytes, uint32_t startingChecksum) {
286 throw std::runtime_error("crc32_hw is not implemented on this platform");