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crc64_vmull.c
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/*
* This file is part of the Aaru Data Preservation Suite.
* Copyright (c) 2019-2026 Natalia Portillo.
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of the
* License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
#if defined(__aarch64__) || defined(_M_ARM64) || defined(__arm__) || defined(_M_ARM)
#include <arm_neon.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <aaruformat.h>
#include "arm_vmull.h"
#include "log.h"
static const uint8_t shuffleMasks[] = {
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x8f, 0x8e, 0x8d, 0x8c, 0x8b, 0x8a, 0x89, 0x88, 0x87, 0x86, 0x85, 0x84, 0x83, 0x82, 0x81, 0x80,
};
TARGET_WITH_SIMD FORCE_INLINE void shiftRight128(uint64x2_t in, size_t n, uint64x2_t *outLeft, uint64x2_t *outRight)
{
const uint64x2_t maskA =
vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)(const uint64x2_t *)(shuffleMasks + (16 - n))));
uint64x2_t b = vreinterpretq_u64_u8(vceqq_u8(vreinterpretq_u8_u64(vreinterpretq_u64_u32(vdupq_n_u32(0))),
vreinterpretq_u8_u64(vreinterpretq_u64_u32(vdupq_n_u32(0)))));
const uint64x2_t maskB = vreinterpretq_u64_u32(veorq_u32(vreinterpretq_u32_u64(maskA), vreinterpretq_u32_u64(b)));
*outLeft = mm_shuffle_epi8(in, maskB);
*outRight = mm_shuffle_epi8(in, maskA);
}
TARGET_WITH_SIMD FORCE_INLINE uint64x2_t fold(uint64x2_t in, uint64x2_t foldConstants)
{
return veorq_u64(sse2neon_vmull_p64(vget_low_u64(in), vget_low_u64(foldConstants)),
sse2neon_vmull_p64(vget_high_u64(in), vget_high_u64(foldConstants)));
}
AARU_EXPORT TARGET_WITH_SIMD uint64_t AARU_CALL aaruf_crc64_vmull(uint64_t previous_crc, const uint8_t *data, long len)
{
TRACE("Entering aaruf_crc64_vmull(%llu, %p, %ld)", previous_crc, data, len);
const uint64_t k1 = 0xe05dd497ca393ae4; // bitReflect(expMod65(128 + 64, poly, 1)) << 1;
const uint64_t k2 = 0xdabe95afc7875f40; // bitReflect(expMod65(128, poly, 1)) << 1;
const uint64_t mu = 0x9c3e466c172963d5; // (bitReflect(div129by65(poly)) << 1) | 1;
const uint64_t p = 0x92d8af2baf0e1e85; // (bitReflect(poly) << 1) | 1;
const uint64x2_t foldConstants1 = vcombine_u64(vcreate_u64(k1), vcreate_u64(k2));
const uint64x2_t foldConstants2 = vcombine_u64(vcreate_u64(mu), vcreate_u64(p));
const uint8_t *end = data + len;
// Align pointers
const uint64x2_t *alignedData = (const uint64x2_t *)((uintptr_t)data & ~(uintptr_t)15);
const uint64x2_t *alignedEnd = (const uint64x2_t *)(((uintptr_t)end + 15) & ~(uintptr_t)15);
const size_t leadInSize = data - (const uint8_t *)alignedData;
const size_t leadOutSize = (const uint8_t *)alignedEnd - end;
const size_t alignedLength = alignedEnd - alignedData;
const uint64x2_t leadInMask =
vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)(const uint64x2_t *)(shuffleMasks + (16 - leadInSize))));
uint64x2_t a = vreinterpretq_u64_u32(vdupq_n_u32(0));
uint64x2_t b = vreinterpretq_u64_u32(
vld1q_u32((const uint32_t *)alignedData)); // Use a signed shift right to create a mask with the sign bit
const uint64x2_t data0 =
vreinterpretq_u64_u8(vbslq_u8(vreinterpretq_u8_s8(vshrq_n_s8(vreinterpretq_s8_u64(leadInMask), 7)),
vreinterpretq_u8_u64(b), vreinterpretq_u8_u64(a)));
const uint64x2_t initialCrc = vsetq_lane_u64(~previous_crc, vdupq_n_u64(0), 0);
uint64x2_t R;
if(alignedLength == 1)
{
// Single data block, initial CRC possibly bleeds into zero padding
uint64x2_t crc0, crc1;
shiftRight128(initialCrc, 16 - len, &crc0, &crc1);
uint64x2_t A, B;
shiftRight128(data0, leadOutSize, &A, &B);
const uint64x2_t P = veorq_u64(A, crc0);
R = veorq_u64(sse2neon_vmull_p64(vget_low_u64(P), vget_high_u64(foldConstants1)),
veorq_u64(mm_srli_si128(P, 8), mm_slli_si128(crc1, 8)));
}
else if(alignedLength == 2)
{
const uint64x2_t data1 = vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)(alignedData + 1)));
if(len < 8)
{
// Initial CRC bleeds into the zero padding
uint64x2_t crc0, crc1;
shiftRight128(initialCrc, 16 - len, &crc0, &crc1);
uint64x2_t A, B, C, D;
shiftRight128(data0, leadOutSize, &A, &B);
shiftRight128(data1, leadOutSize, &C, &D);
const uint64x2_t P = veorq_u64(veorq_u64(B, C), crc0);
R = veorq_u64(sse2neon_vmull_p64(vget_low_u64(P), vget_high_u64(foldConstants1)),
veorq_u64(mm_srli_si128(P, 8), mm_slli_si128(crc1, 8)));
}
else
{
// We can fit the initial CRC into the data without bleeding into the zero padding
uint64x2_t crc0, crc1;
shiftRight128(initialCrc, leadInSize, &crc0, &crc1);
uint64x2_t A, B, C, D;
shiftRight128(veorq_u64(data0, crc0), leadOutSize, &A, &B);
shiftRight128(veorq_u64(data1, crc1), leadOutSize, &C, &D);
const uint64x2_t P = veorq_u64(fold(A, foldConstants1), veorq_u64(B, C));
R = veorq_u64(sse2neon_vmull_p64(vget_low_u64(P), vget_high_u64(foldConstants1)), mm_srli_si128(P, 8));
}
}
else
{
alignedData++;
len -= 16 - leadInSize;
// Initial CRC can simply be added to data
uint64x2_t crc0, crc1;
shiftRight128(initialCrc, leadInSize, &crc0, &crc1);
uint64x2_t accumulator = veorq_u64(fold(veorq_u64(crc0, data0), foldConstants1), crc1);
while(len >= 32)
{
accumulator = fold(veorq_u64(vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)alignedData)), accumulator),
foldConstants1);
len -= 16;
alignedData++;
}
uint64x2_t P;
if(len == 16)
P = veorq_u64(accumulator, vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)alignedData)));
else
{
// When len is between 16 and 32, we need both blocks but must be careful not to read past buffer end
const uint64x2_t end0 =
veorq_u64(accumulator, vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)alignedData)));
// For the second block, always use safe copy to avoid buffer overflow
// The algorithm expects to read up to alignedEnd, but ASan prevents over-reading
uint8_t temp[16] __attribute__((aligned(16))) = {0};
const uint8_t *nextBlockAddr = (const uint8_t *)(alignedData + 1);
// Only copy bytes that are actually within the original buffer
if(nextBlockAddr < end)
{
size_t available = (size_t)(end - nextBlockAddr);
if(available > 16) available = 16;
memcpy(temp, nextBlockAddr, available);
}
const uint64x2_t end1 = vreinterpretq_u64_u32(vld1q_u32((const uint32_t *)temp));
uint64x2_t A, B, C, D;
shiftRight128(end0, leadOutSize, &A, &B);
shiftRight128(end1, leadOutSize, &C, &D);
P = veorq_u64(fold(A, foldConstants1),
vreinterpretq_u64_u32(vorrq_u32(vreinterpretq_u32_u64(B), vreinterpretq_u32_u64(C))));
}
R = veorq_u64(sse2neon_vmull_p64(vget_low_u64(P), vget_high_u64(foldConstants1)), mm_srli_si128(P, 8));
}
// Final Barrett reduction
const uint64x2_t T1 = sse2neon_vmull_p64(vget_low_u64(R), vget_low_u64(foldConstants2));
const uint64x2_t T2 = veorq_u64(
veorq_u64(sse2neon_vmull_p64(vget_low_u64(T1), vget_high_u64(foldConstants2)), mm_slli_si128(T1, 8)), R);
TRACE("Exiting aaruf_crc64_vmull()");
return ~vgetq_lane_u64(T2, 1);
}
#endif
aaruformat.h
arm_vmull.h
AARU_CALL
#define AARU_CALL
Definition decls.h:46
AARU_EXPORT
#define AARU_EXPORT
Definition decls.h:55
FORCE_INLINE
#define FORCE_INLINE
Definition decls.h:64
log.h
TRACE
#define TRACE(fmt,...)
Definition log.h:25
__attribute__
static __attribute__((always_inline))
Definition lru.c:76