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Add ARMv8 CRC32C support. #18

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Add ARMv8 CRC32C support. #18

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8 changes: 7 additions & 1 deletion README
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Original file line number Diff line number Diff line change
Expand Up @@ -99,12 +99,18 @@ On systems with gcc, we generally recommend:
make all check CXXFLAGS="-g -O3"
sudo make install

Or, if your system has the CRC32 instruction, and you want to build everything:
If your system has the SSE CRC32 instruction, and you want to build everything:

./configure --enable-sse4.2
make all check CXXFLAGS="-g -O3 -msse4.2"
sudo make install

Or, for the ARMv8 CRC32C instruction:

./configure --enable-sse4.2
make all check CXXFLAGS="-g -O3 -march=armv8-a+crc"
sudo make install

Note that our build system doesn't try to determine the appropriate compiler
flag for enabling SSE4.2. For gcc it is "-msse4.2". The --enable-sse4.2
flag to the configure script controls whether citycrc.h is installed when
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4 changes: 2 additions & 2 deletions src/city-test.cc
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Expand Up @@ -22,7 +22,7 @@
#include <iostream>
#include <string.h>
#include "city.h"
#ifdef __SSE4_2__
#if defined __SSE4_2__ || defined __ARM_FEATURE_CRC32
#include "citycrc.h"
#endif

Expand Down Expand Up @@ -1279,7 +1279,7 @@ void Test(const uint64* expected, int offset, int len) {
Check(expected[4], Uint128High64(u));
Check(expected[5], Uint128Low64(v));
Check(expected[6], Uint128High64(v));
#ifdef __SSE4_2__
#if defined __SSE4_2__ || defined __ARM_FEATURE_CRC32
const uint128 y = CityHashCrc128(data + offset, len);
const uint128 z = CityHashCrc128WithSeed(data + offset, len, kSeed128);
uint64 crc256_results[4];
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15 changes: 11 additions & 4 deletions src/city.cc
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Expand Up @@ -512,9 +512,16 @@ uint128 CityHash128(const char *s, size_t len) {
CityHash128WithSeed(s, len, uint128(k0, k1));
}

#ifdef __SSE4_2__
#if defined __SSE4_2__ || defined __ARM_FEATURE_CRC32
#include <citycrc.h>
#ifdef __SSE4_2__
#include <nmmintrin.h>
#define crc32_u64 _mm_crc32_u64
#endif
#ifdef __ARM_FEATURE_CRC32
#include <arm_acle.h>
#define crc32_u64 __crc32cd
#endif

// Requires len >= 240.
static void CityHashCrc256Long(const char *s, size_t len,
Expand Down Expand Up @@ -550,9 +557,9 @@ static void CityHashCrc256Long(const char *s, size_t len,
g += e; \
e += z; \
g += x; \
z = _mm_crc32_u64(z, b + g); \
y = _mm_crc32_u64(y, e + h); \
x = _mm_crc32_u64(x, f + a); \
z = crc32_u64(z, b + g); \
y = crc32_u64(y, e + h); \
x = crc32_u64(x, f + a); \
e = Rotate(e, r); \
c += e; \
s += 40
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