mariadb/mysys/crc32/crc32c_amd64.cc
Marko Mäkelä d9d0e8fd60 MDEV-34321: call to crc32c_3way through pointer to incorrect function type
In commit 9ec7819c58 the CRC-32 function
signatures had been unified somewhat, but not enough.

clang -fsanitize=undefined would flag a function pointer signature
mismatch between const char* and const void*, but not between
uint32_t and unsigned. We try to fix both inconsistencies anyway.

Reviewed by: Vladislav Vaintroub
2024-06-07 13:51:46 +03:00

719 lines
24 KiB
C++

/* Copyright (c) 2020, 2021, MariaDB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
/*
* Copyright 2016 Ferry Toth, Exalon Delft BV, The Netherlands
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the author be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
* Ferry Toth
* ftoth@exalondelft.nl
*
* https://github.com/htot/crc32c
*
* Modified by Facebook
*
* Original intel whitepaper:
* "Fast CRC Computation for iSCSI Polynomial Using CRC32 Instruction"
* https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/crc-iscsi-polynomial-crc32-instruction-paper.pdf
*
* This version is from the folly library, created by Dave Watson <davejwatson@fb.com>
*
*/
#include <stdint.h>
#include <nmmintrin.h>
#include <wmmintrin.h>
#ifdef _MSC_VER
# define USE_PCLMUL /* nothing */
#else
# define USE_PCLMUL __attribute__((target("sse4.2,pclmul")))
#endif
#define CRCtriplet(crc, buf, offset) \
crc##0 = _mm_crc32_u64(crc##0, *(buf##0 + offset)); \
crc##1 = _mm_crc32_u64(crc##1, *(buf##1 + offset)); \
crc##2 = _mm_crc32_u64(crc##2, *(buf##2 + offset));
#define CRCduplet(crc, buf, offset) \
crc##0 = _mm_crc32_u64(crc##0, *(buf##0 + offset)); \
crc##1 = _mm_crc32_u64(crc##1, *(buf##1 + offset));
#define CRCsinglet(crc, buf, offset) \
crc = _mm_crc32_u64(crc, *(uint64_t*)(buf + offset));
// Numbers taken directly from intel whitepaper.
// clang-format off
static const uint64_t clmul_constants alignas(16) [] = {
0x14cd00bd6, 0x105ec76f0, 0x0ba4fc28e, 0x14cd00bd6,
0x1d82c63da, 0x0f20c0dfe, 0x09e4addf8, 0x0ba4fc28e,
0x039d3b296, 0x1384aa63a, 0x102f9b8a2, 0x1d82c63da,
0x14237f5e6, 0x01c291d04, 0x00d3b6092, 0x09e4addf8,
0x0c96cfdc0, 0x0740eef02, 0x18266e456, 0x039d3b296,
0x0daece73e, 0x0083a6eec, 0x0ab7aff2a, 0x102f9b8a2,
0x1248ea574, 0x1c1733996, 0x083348832, 0x14237f5e6,
0x12c743124, 0x02ad91c30, 0x0b9e02b86, 0x00d3b6092,
0x018b33a4e, 0x06992cea2, 0x1b331e26a, 0x0c96cfdc0,
0x17d35ba46, 0x07e908048, 0x1bf2e8b8a, 0x18266e456,
0x1a3e0968a, 0x11ed1f9d8, 0x0ce7f39f4, 0x0daece73e,
0x061d82e56, 0x0f1d0f55e, 0x0d270f1a2, 0x0ab7aff2a,
0x1c3f5f66c, 0x0a87ab8a8, 0x12ed0daac, 0x1248ea574,
0x065863b64, 0x08462d800, 0x11eef4f8e, 0x083348832,
0x1ee54f54c, 0x071d111a8, 0x0b3e32c28, 0x12c743124,
0x0064f7f26, 0x0ffd852c6, 0x0dd7e3b0c, 0x0b9e02b86,
0x0f285651c, 0x0dcb17aa4, 0x010746f3c, 0x018b33a4e,
0x1c24afea4, 0x0f37c5aee, 0x0271d9844, 0x1b331e26a,
0x08e766a0c, 0x06051d5a2, 0x093a5f730, 0x17d35ba46,
0x06cb08e5c, 0x11d5ca20e, 0x06b749fb2, 0x1bf2e8b8a,
0x1167f94f2, 0x021f3d99c, 0x0cec3662e, 0x1a3e0968a,
0x19329634a, 0x08f158014, 0x0e6fc4e6a, 0x0ce7f39f4,
0x08227bb8a, 0x1a5e82106, 0x0b0cd4768, 0x061d82e56,
0x13c2b89c4, 0x188815ab2, 0x0d7a4825c, 0x0d270f1a2,
0x10f5ff2ba, 0x105405f3e, 0x00167d312, 0x1c3f5f66c,
0x0f6076544, 0x0e9adf796, 0x026f6a60a, 0x12ed0daac,
0x1a2adb74e, 0x096638b34, 0x19d34af3a, 0x065863b64,
0x049c3cc9c, 0x1e50585a0, 0x068bce87a, 0x11eef4f8e,
0x1524fa6c6, 0x19f1c69dc, 0x16cba8aca, 0x1ee54f54c,
0x042d98888, 0x12913343e, 0x1329d9f7e, 0x0b3e32c28,
0x1b1c69528, 0x088f25a3a, 0x02178513a, 0x0064f7f26,
0x0e0ac139e, 0x04e36f0b0, 0x0170076fa, 0x0dd7e3b0c,
0x141a1a2e2, 0x0bd6f81f8, 0x16ad828b4, 0x0f285651c,
0x041d17b64, 0x19425cbba, 0x1fae1cc66, 0x010746f3c,
0x1a75b4b00, 0x18db37e8a, 0x0f872e54c, 0x1c24afea4,
0x01e41e9fc, 0x04c144932, 0x086d8e4d2, 0x0271d9844,
0x160f7af7a, 0x052148f02, 0x05bb8f1bc, 0x08e766a0c,
0x0a90fd27a, 0x0a3c6f37a, 0x0b3af077a, 0x093a5f730,
0x04984d782, 0x1d22c238e, 0x0ca6ef3ac, 0x06cb08e5c,
0x0234e0b26, 0x063ded06a, 0x1d88abd4a, 0x06b749fb2,
0x04597456a, 0x04d56973c, 0x0e9e28eb4, 0x1167f94f2,
0x07b3ff57a, 0x19385bf2e, 0x0c9c8b782, 0x0cec3662e,
0x13a9cba9e, 0x0e417f38a, 0x093e106a4, 0x19329634a,
0x167001a9c, 0x14e727980, 0x1ddffc5d4, 0x0e6fc4e6a,
0x00df04680, 0x0d104b8fc, 0x02342001e, 0x08227bb8a,
0x00a2a8d7e, 0x05b397730, 0x168763fa6, 0x0b0cd4768,
0x1ed5a407a, 0x0e78eb416, 0x0d2c3ed1a, 0x13c2b89c4,
0x0995a5724, 0x1641378f0, 0x19b1afbc4, 0x0d7a4825c,
0x109ffedc0, 0x08d96551c, 0x0f2271e60, 0x10f5ff2ba,
0x00b0bf8ca, 0x00bf80dd2, 0x123888b7a, 0x00167d312,
0x1e888f7dc, 0x18dcddd1c, 0x002ee03b2, 0x0f6076544,
0x183e8d8fe, 0x06a45d2b2, 0x133d7a042, 0x026f6a60a,
0x116b0f50c, 0x1dd3e10e8, 0x05fabe670, 0x1a2adb74e,
0x130004488, 0x0de87806c, 0x000bcf5f6, 0x19d34af3a,
0x18f0c7078, 0x014338754, 0x017f27698, 0x049c3cc9c,
0x058ca5f00, 0x15e3e77ee, 0x1af900c24, 0x068bce87a,
0x0b5cfca28, 0x0dd07448e, 0x0ded288f8, 0x1524fa6c6,
0x059f229bc, 0x1d8048348, 0x06d390dec, 0x16cba8aca,
0x037170390, 0x0a3e3e02c, 0x06353c1cc, 0x042d98888,
0x0c4584f5c, 0x0d73c7bea, 0x1f16a3418, 0x1329d9f7e,
0x0531377e2, 0x185137662, 0x1d8d9ca7c, 0x1b1c69528,
0x0b25b29f2, 0x18a08b5bc, 0x19fb2a8b0, 0x02178513a,
0x1a08fe6ac, 0x1da758ae0, 0x045cddf4e, 0x0e0ac139e,
0x1a91647f2, 0x169cf9eb0, 0x1a0f717c4, 0x0170076fa,
};
// Compute the crc32c value for buffer smaller than 8
USE_PCLMUL
static inline void align_to_8(
size_t len,
uint64_t& crc0, // crc so far, updated on return
const unsigned char*& next) { // next data pointer, updated on return
uint32_t crc32bit = static_cast<uint32_t>(crc0);
if (len & 0x04) {
crc32bit = _mm_crc32_u32(crc32bit, *(uint32_t*)next);
next += sizeof(uint32_t);
}
if (len & 0x02) {
crc32bit = _mm_crc32_u16(crc32bit, *(uint16_t*)next);
next += sizeof(uint16_t);
}
if (len & 0x01) {
crc32bit = _mm_crc32_u8(crc32bit, *(next));
next++;
}
crc0 = crc32bit;
}
//
// CombineCRC performs pclmulqdq multiplication of 2 partial CRC's and a well
// chosen constant and xor's these with the remaining CRC.
//
USE_PCLMUL
static inline uint64_t CombineCRC(
size_t block_size,
uint64_t crc0,
uint64_t crc1,
uint64_t crc2,
const uint64_t* next2) {
const auto multiplier =
*(reinterpret_cast<const __m128i*>(clmul_constants) + block_size - 1);
const auto crc0_xmm = _mm_set_epi64x(0, crc0);
const auto res0 = _mm_clmulepi64_si128(crc0_xmm, multiplier, 0x00);
const auto crc1_xmm = _mm_set_epi64x(0, crc1);
const auto res1 = _mm_clmulepi64_si128(crc1_xmm, multiplier, 0x10);
const auto res = _mm_xor_si128(res0, res1);
crc0 = _mm_cvtsi128_si64(res);
crc0 = crc0 ^ *((uint64_t*)next2 - 1);
crc2 = _mm_crc32_u64(crc2, crc0);
return crc2;
}
// Compute CRC-32C using the Intel hardware instruction.
extern "C"
USE_PCLMUL
uint32_t crc32c_3way(uint32_t crc, const void *buf, size_t len)
{
const unsigned char* next = static_cast<const unsigned char*>(buf);
uint64_t count;
uint64_t crc0, crc1, crc2;
crc0 = crc ^ 0xffffffffu;
if (len >= 8) {
// if len > 216 then align and use triplets
if (len > 216) {
{
// Work on the bytes (< 8) before the first 8-byte alignment addr starts
auto align_bytes = (8 - (uintptr_t)next) & 7;
len -= align_bytes;
align_to_8(align_bytes, crc0, next);
}
// Now work on the remaining blocks
count = len / 24; // number of triplets
len %= 24; // bytes remaining
uint64_t n = count >> 7; // #blocks = first block + full blocks
uint64_t block_size = count & 127;
if (block_size == 0) {
block_size = 128;
} else {
n++;
}
// points to the first byte of the next block
const uint64_t* next0 = (uint64_t*)next + block_size;
const uint64_t* next1 = next0 + block_size;
const uint64_t* next2 = next1 + block_size;
crc1 = crc2 = 0;
// Use Duff's device, a for() loop inside a switch()
// statement. This needs to execute at least once, round len
// down to nearest triplet multiple
switch (block_size) {
case 128:
do {
// jumps here for a full block of len 128
CRCtriplet(crc, next, -128);
/* fallthrough */
case 127:
// jumps here or below for the first block smaller
CRCtriplet(crc, next, -127);
/* fallthrough */
case 126:
CRCtriplet(crc, next, -126); // than 128
/* fallthrough */
case 125:
CRCtriplet(crc, next, -125);
/* fallthrough */
case 124:
CRCtriplet(crc, next, -124);
/* fallthrough */
case 123:
CRCtriplet(crc, next, -123);
/* fallthrough */
case 122:
CRCtriplet(crc, next, -122);
/* fallthrough */
case 121:
CRCtriplet(crc, next, -121);
/* fallthrough */
case 120:
CRCtriplet(crc, next, -120);
/* fallthrough */
case 119:
CRCtriplet(crc, next, -119);
/* fallthrough */
case 118:
CRCtriplet(crc, next, -118);
/* fallthrough */
case 117:
CRCtriplet(crc, next, -117);
/* fallthrough */
case 116:
CRCtriplet(crc, next, -116);
/* fallthrough */
case 115:
CRCtriplet(crc, next, -115);
/* fallthrough */
case 114:
CRCtriplet(crc, next, -114);
/* fallthrough */
case 113:
CRCtriplet(crc, next, -113);
/* fallthrough */
case 112:
CRCtriplet(crc, next, -112);
/* fallthrough */
case 111:
CRCtriplet(crc, next, -111);
/* fallthrough */
case 110:
CRCtriplet(crc, next, -110);
/* fallthrough */
case 109:
CRCtriplet(crc, next, -109);
/* fallthrough */
case 108:
CRCtriplet(crc, next, -108);
/* fallthrough */
case 107:
CRCtriplet(crc, next, -107);
/* fallthrough */
case 106:
CRCtriplet(crc, next, -106);
/* fallthrough */
case 105:
CRCtriplet(crc, next, -105);
/* fallthrough */
case 104:
CRCtriplet(crc, next, -104);
/* fallthrough */
case 103:
CRCtriplet(crc, next, -103);
/* fallthrough */
case 102:
CRCtriplet(crc, next, -102);
/* fallthrough */
case 101:
CRCtriplet(crc, next, -101);
/* fallthrough */
case 100:
CRCtriplet(crc, next, -100);
/* fallthrough */
case 99:
CRCtriplet(crc, next, -99);
/* fallthrough */
case 98:
CRCtriplet(crc, next, -98);
/* fallthrough */
case 97:
CRCtriplet(crc, next, -97);
/* fallthrough */
case 96:
CRCtriplet(crc, next, -96);
/* fallthrough */
case 95:
CRCtriplet(crc, next, -95);
/* fallthrough */
case 94:
CRCtriplet(crc, next, -94);
/* fallthrough */
case 93:
CRCtriplet(crc, next, -93);
/* fallthrough */
case 92:
CRCtriplet(crc, next, -92);
/* fallthrough */
case 91:
CRCtriplet(crc, next, -91);
/* fallthrough */
case 90:
CRCtriplet(crc, next, -90);
/* fallthrough */
case 89:
CRCtriplet(crc, next, -89);
/* fallthrough */
case 88:
CRCtriplet(crc, next, -88);
/* fallthrough */
case 87:
CRCtriplet(crc, next, -87);
/* fallthrough */
case 86:
CRCtriplet(crc, next, -86);
/* fallthrough */
case 85:
CRCtriplet(crc, next, -85);
/* fallthrough */
case 84:
CRCtriplet(crc, next, -84);
/* fallthrough */
case 83:
CRCtriplet(crc, next, -83);
/* fallthrough */
case 82:
CRCtriplet(crc, next, -82);
/* fallthrough */
case 81:
CRCtriplet(crc, next, -81);
/* fallthrough */
case 80:
CRCtriplet(crc, next, -80);
/* fallthrough */
case 79:
CRCtriplet(crc, next, -79);
/* fallthrough */
case 78:
CRCtriplet(crc, next, -78);
/* fallthrough */
case 77:
CRCtriplet(crc, next, -77);
/* fallthrough */
case 76:
CRCtriplet(crc, next, -76);
/* fallthrough */
case 75:
CRCtriplet(crc, next, -75);
/* fallthrough */
case 74:
CRCtriplet(crc, next, -74);
/* fallthrough */
case 73:
CRCtriplet(crc, next, -73);
/* fallthrough */
case 72:
CRCtriplet(crc, next, -72);
/* fallthrough */
case 71:
CRCtriplet(crc, next, -71);
/* fallthrough */
case 70:
CRCtriplet(crc, next, -70);
/* fallthrough */
case 69:
CRCtriplet(crc, next, -69);
/* fallthrough */
case 68:
CRCtriplet(crc, next, -68);
/* fallthrough */
case 67:
CRCtriplet(crc, next, -67);
/* fallthrough */
case 66:
CRCtriplet(crc, next, -66);
/* fallthrough */
case 65:
CRCtriplet(crc, next, -65);
/* fallthrough */
case 64:
CRCtriplet(crc, next, -64);
/* fallthrough */
case 63:
CRCtriplet(crc, next, -63);
/* fallthrough */
case 62:
CRCtriplet(crc, next, -62);
/* fallthrough */
case 61:
CRCtriplet(crc, next, -61);
/* fallthrough */
case 60:
CRCtriplet(crc, next, -60);
/* fallthrough */
case 59:
CRCtriplet(crc, next, -59);
/* fallthrough */
case 58:
CRCtriplet(crc, next, -58);
/* fallthrough */
case 57:
CRCtriplet(crc, next, -57);
/* fallthrough */
case 56:
CRCtriplet(crc, next, -56);
/* fallthrough */
case 55:
CRCtriplet(crc, next, -55);
/* fallthrough */
case 54:
CRCtriplet(crc, next, -54);
/* fallthrough */
case 53:
CRCtriplet(crc, next, -53);
/* fallthrough */
case 52:
CRCtriplet(crc, next, -52);
/* fallthrough */
case 51:
CRCtriplet(crc, next, -51);
/* fallthrough */
case 50:
CRCtriplet(crc, next, -50);
/* fallthrough */
case 49:
CRCtriplet(crc, next, -49);
/* fallthrough */
case 48:
CRCtriplet(crc, next, -48);
/* fallthrough */
case 47:
CRCtriplet(crc, next, -47);
/* fallthrough */
case 46:
CRCtriplet(crc, next, -46);
/* fallthrough */
case 45:
CRCtriplet(crc, next, -45);
/* fallthrough */
case 44:
CRCtriplet(crc, next, -44);
/* fallthrough */
case 43:
CRCtriplet(crc, next, -43);
/* fallthrough */
case 42:
CRCtriplet(crc, next, -42);
/* fallthrough */
case 41:
CRCtriplet(crc, next, -41);
/* fallthrough */
case 40:
CRCtriplet(crc, next, -40);
/* fallthrough */
case 39:
CRCtriplet(crc, next, -39);
/* fallthrough */
case 38:
CRCtriplet(crc, next, -38);
/* fallthrough */
case 37:
CRCtriplet(crc, next, -37);
/* fallthrough */
case 36:
CRCtriplet(crc, next, -36);
/* fallthrough */
case 35:
CRCtriplet(crc, next, -35);
/* fallthrough */
case 34:
CRCtriplet(crc, next, -34);
/* fallthrough */
case 33:
CRCtriplet(crc, next, -33);
/* fallthrough */
case 32:
CRCtriplet(crc, next, -32);
/* fallthrough */
case 31:
CRCtriplet(crc, next, -31);
/* fallthrough */
case 30:
CRCtriplet(crc, next, -30);
/* fallthrough */
case 29:
CRCtriplet(crc, next, -29);
/* fallthrough */
case 28:
CRCtriplet(crc, next, -28);
/* fallthrough */
case 27:
CRCtriplet(crc, next, -27);
/* fallthrough */
case 26:
CRCtriplet(crc, next, -26);
/* fallthrough */
case 25:
CRCtriplet(crc, next, -25);
/* fallthrough */
case 24:
CRCtriplet(crc, next, -24);
/* fallthrough */
case 23:
CRCtriplet(crc, next, -23);
/* fallthrough */
case 22:
CRCtriplet(crc, next, -22);
/* fallthrough */
case 21:
CRCtriplet(crc, next, -21);
/* fallthrough */
case 20:
CRCtriplet(crc, next, -20);
/* fallthrough */
case 19:
CRCtriplet(crc, next, -19);
/* fallthrough */
case 18:
CRCtriplet(crc, next, -18);
/* fallthrough */
case 17:
CRCtriplet(crc, next, -17);
/* fallthrough */
case 16:
CRCtriplet(crc, next, -16);
/* fallthrough */
case 15:
CRCtriplet(crc, next, -15);
/* fallthrough */
case 14:
CRCtriplet(crc, next, -14);
/* fallthrough */
case 13:
CRCtriplet(crc, next, -13);
/* fallthrough */
case 12:
CRCtriplet(crc, next, -12);
/* fallthrough */
case 11:
CRCtriplet(crc, next, -11);
/* fallthrough */
case 10:
CRCtriplet(crc, next, -10);
/* fallthrough */
case 9:
CRCtriplet(crc, next, -9);
/* fallthrough */
case 8:
CRCtriplet(crc, next, -8);
/* fallthrough */
case 7:
CRCtriplet(crc, next, -7);
/* fallthrough */
case 6:
CRCtriplet(crc, next, -6);
/* fallthrough */
case 5:
CRCtriplet(crc, next, -5);
/* fallthrough */
case 4:
CRCtriplet(crc, next, -4);
/* fallthrough */
case 3:
CRCtriplet(crc, next, -3);
/* fallthrough */
case 2:
CRCtriplet(crc, next, -2);
/* fallthrough */
case 1:
CRCduplet(crc, next, -1); // the final triplet is actually only 2
//{ CombineCRC(); }
crc0 = CombineCRC(block_size, crc0, crc1, crc2, next2);
if (--n > 0) {
crc1 = crc2 = 0;
block_size = 128;
// points to the first byte of the next block
next0 = next2 + 128;
next1 = next0 + 128; // from here on all blocks are 128 long
next2 = next1 + 128;
}
/* fallthrough */
case 0:;
} while (n > 0);
}
next = (const unsigned char*)next2;
}
uint64_t count2 = len >> 3; // 216 of less bytes is 27 or less singlets
len = len & 7;
next += (count2 * 8);
switch (count2) {
case 27:
CRCsinglet(crc0, next, -27 * 8);
/* fallthrough */
case 26:
CRCsinglet(crc0, next, -26 * 8);
/* fallthrough */
case 25:
CRCsinglet(crc0, next, -25 * 8);
/* fallthrough */
case 24:
CRCsinglet(crc0, next, -24 * 8);
/* fallthrough */
case 23:
CRCsinglet(crc0, next, -23 * 8);
/* fallthrough */
case 22:
CRCsinglet(crc0, next, -22 * 8);
/* fallthrough */
case 21:
CRCsinglet(crc0, next, -21 * 8);
/* fallthrough */
case 20:
CRCsinglet(crc0, next, -20 * 8);
/* fallthrough */
case 19:
CRCsinglet(crc0, next, -19 * 8);
/* fallthrough */
case 18:
CRCsinglet(crc0, next, -18 * 8);
/* fallthrough */
case 17:
CRCsinglet(crc0, next, -17 * 8);
/* fallthrough */
case 16:
CRCsinglet(crc0, next, -16 * 8);
/* fallthrough */
case 15:
CRCsinglet(crc0, next, -15 * 8);
/* fallthrough */
case 14:
CRCsinglet(crc0, next, -14 * 8);
/* fallthrough */
case 13:
CRCsinglet(crc0, next, -13 * 8);
/* fallthrough */
case 12:
CRCsinglet(crc0, next, -12 * 8);
/* fallthrough */
case 11:
CRCsinglet(crc0, next, -11 * 8);
/* fallthrough */
case 10:
CRCsinglet(crc0, next, -10 * 8);
/* fallthrough */
case 9:
CRCsinglet(crc0, next, -9 * 8);
/* fallthrough */
case 8:
CRCsinglet(crc0, next, -8 * 8);
/* fallthrough */
case 7:
CRCsinglet(crc0, next, -7 * 8);
/* fallthrough */
case 6:
CRCsinglet(crc0, next, -6 * 8);
/* fallthrough */
case 5:
CRCsinglet(crc0, next, -5 * 8);
/* fallthrough */
case 4:
CRCsinglet(crc0, next, -4 * 8);
/* fallthrough */
case 3:
CRCsinglet(crc0, next, -3 * 8);
/* fallthrough */
case 2:
CRCsinglet(crc0, next, -2 * 8);
/* fallthrough */
case 1:
CRCsinglet(crc0, next, -1 * 8);
/* fallthrough */
case 0:;
}
}
{
align_to_8(len, crc0, next);
return (uint32_t)crc0 ^ 0xffffffffu;
}
}