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// Copyright 2017 The CRC32C Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "./crc32c_arm64.h"
// In a separate source file to allow this accelerated CRC32C function to be
// compiled with the appropriate compiler flags to enable ARM NEON CRC32C
// instructions.
// This implementation is based on https://github.com/google/leveldb/pull/490.
#include <cstddef>
#include <cstdint>
#include "./crc32c_internal.h"
#ifdef CRC32C_HAVE_CONFIG_H
#include "crc32c/crc32c_config.h"
#endif
#if HAVE_ARM64_CRC32C
#include <arm_acle.h>
#include <arm_neon.h>
#define KBYTES 1032
#define SEGMENTBYTES 256
// compute 8bytes for each segment parallelly
#define CRC32C32BYTES(P, IND) \
do { \
crc1 = __crc32cd( \
crc1, *((const uint64_t *)(P) + (SEGMENTBYTES / 8) * 1 + (IND))); \
crc2 = __crc32cd( \
crc2, *((const uint64_t *)(P) + (SEGMENTBYTES / 8) * 2 + (IND))); \
crc3 = __crc32cd( \
crc3, *((const uint64_t *)(P) + (SEGMENTBYTES / 8) * 3 + (IND))); \
crc0 = __crc32cd( \
crc0, *((const uint64_t *)(P) + (SEGMENTBYTES / 8) * 0 + (IND))); \
} while (0);
// compute 8*8 bytes for each segment parallelly
#define CRC32C256BYTES(P, IND) \
do { \
CRC32C32BYTES((P), (IND)*8 + 0) \
CRC32C32BYTES((P), (IND)*8 + 1) \
CRC32C32BYTES((P), (IND)*8 + 2) \
CRC32C32BYTES((P), (IND)*8 + 3) \
CRC32C32BYTES((P), (IND)*8 + 4) \
CRC32C32BYTES((P), (IND)*8 + 5) \
CRC32C32BYTES((P), (IND)*8 + 6) \
CRC32C32BYTES((P), (IND)*8 + 7) \
} while (0);
// compute 4*8*8 bytes for each segment parallelly
#define CRC32C1024BYTES(P) \
do { \
CRC32C256BYTES((P), 0) \
CRC32C256BYTES((P), 1) \
CRC32C256BYTES((P), 2) \
CRC32C256BYTES((P), 3) \
(P) += 4 * SEGMENTBYTES; \
} while (0)
namespace crc32c {
uint32_t ExtendArm64(uint32_t crc, const uint8_t *buf, size_t size) {
int64_t length = size;
uint32_t crc0, crc1, crc2, crc3;
uint64_t t0, t1, t2;
// k0=CRC(x^(3*SEGMENTBYTES*8)), k1=CRC(x^(2*SEGMENTBYTES*8)),
// k2=CRC(x^(SEGMENTBYTES*8))
const poly64_t k0 = 0x8d96551c, k1 = 0xbd6f81f8, k2 = 0xdcb17aa4;
crc = crc ^ kCRC32Xor;
const uint8_t *p = reinterpret_cast<const uint8_t *>(buf);
while (length >= KBYTES) {
crc0 = crc;
crc1 = 0;
crc2 = 0;
crc3 = 0;
// Process 1024 bytes in parallel.
CRC32C1024BYTES(p);
// Merge the 4 partial CRC32C values.
t2 = (uint64_t)vmull_p64(crc2, k2);
t1 = (uint64_t)vmull_p64(crc1, k1);
t0 = (uint64_t)vmull_p64(crc0, k0);
crc = __crc32cd(crc3, *(uint64_t *)p);
p += sizeof(uint64_t);
crc ^= __crc32cd(0, t2);
crc ^= __crc32cd(0, t1);
crc ^= __crc32cd(0, t0);
length -= KBYTES;
}
while (length >= 8) {
crc = __crc32cd(crc, *(uint64_t *)p);
p += 8;
length -= 8;
}
if (length & 4) {
crc = __crc32cw(crc, *(uint32_t *)p);
p += 4;
}
if (length & 2) {
crc = __crc32ch(crc, *(uint16_t *)p);
p += 2;
}
if (length & 1) {
crc = __crc32cb(crc, *p);
}
return crc ^ kCRC32Xor;
}
} // namespace crc32c
#endif // HAVE_ARM64_CRC32C
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