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common/cityhash: Use common types
Allow sharing return types with the rest of the code base. For example, we use 'u128 = std::array<u64, 2>', meanwhile Google's code uses 'uint128 = std::pair<u64, u64>'. While we are at it, use size_t instead of std::size_t.
This commit is contained in:
ReinUsesLisp
parent
9ca5e52f07
commit
f3805376f7
3 changed files with 100 additions and 116 deletions
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@ -28,8 +28,10 @@
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// compromising on hash quality.
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#include <algorithm>
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#include <string.h> // for memcpy and memset
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#include "cityhash.h"
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#include <cstring>
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#include <utility>
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#include "common/cityhash.h"
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#include "common/swap.h"
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// #include "config.h"
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@ -42,21 +44,17 @@
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using namespace std;
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typedef uint8_t uint8;
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typedef uint32_t uint32;
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typedef uint64_t uint64;
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namespace Common {
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static uint64 UNALIGNED_LOAD64(const char* p) {
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uint64 result;
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memcpy(&result, p, sizeof(result));
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static u64 unaligned_load64(const char* p) {
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u64 result;
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std::memcpy(&result, p, sizeof(result));
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return result;
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}
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static uint32 UNALIGNED_LOAD32(const char* p) {
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uint32 result;
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memcpy(&result, p, sizeof(result));
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static u32 unaligned_load32(const char* p) {
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u32 result;
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std::memcpy(&result, p, sizeof(result));
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return result;
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}
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@ -76,64 +74,64 @@ static uint32 UNALIGNED_LOAD32(const char* p) {
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#endif
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#endif
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static uint64 Fetch64(const char* p) {
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return uint64_in_expected_order(UNALIGNED_LOAD64(p));
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static u64 Fetch64(const char* p) {
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return uint64_in_expected_order(unaligned_load64(p));
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}
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static uint32 Fetch32(const char* p) {
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return uint32_in_expected_order(UNALIGNED_LOAD32(p));
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static u32 Fetch32(const char* p) {
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return uint32_in_expected_order(unaligned_load32(p));
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}
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// Some primes between 2^63 and 2^64 for various uses.
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static const uint64 k0 = 0xc3a5c85c97cb3127ULL;
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static const uint64 k1 = 0xb492b66fbe98f273ULL;
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static const uint64 k2 = 0x9ae16a3b2f90404fULL;
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static constexpr u64 k0 = 0xc3a5c85c97cb3127ULL;
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static constexpr u64 k1 = 0xb492b66fbe98f273ULL;
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static constexpr u64 k2 = 0x9ae16a3b2f90404fULL;
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// Bitwise right rotate. Normally this will compile to a single
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// instruction, especially if the shift is a manifest constant.
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static uint64 Rotate(uint64 val, int shift) {
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static u64 Rotate(u64 val, int shift) {
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// Avoid shifting by 64: doing so yields an undefined result.
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return shift == 0 ? val : ((val >> shift) | (val << (64 - shift)));
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}
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static uint64 ShiftMix(uint64 val) {
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static u64 ShiftMix(u64 val) {
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return val ^ (val >> 47);
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}
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static uint64 HashLen16(uint64 u, uint64 v) {
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return Hash128to64(uint128(u, v));
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static u64 HashLen16(u64 u, u64 v) {
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return Hash128to64(u128{u, v});
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}
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static uint64 HashLen16(uint64 u, uint64 v, uint64 mul) {
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static u64 HashLen16(u64 u, u64 v, u64 mul) {
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// Murmur-inspired hashing.
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uint64 a = (u ^ v) * mul;
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u64 a = (u ^ v) * mul;
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a ^= (a >> 47);
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uint64 b = (v ^ a) * mul;
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u64 b = (v ^ a) * mul;
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b ^= (b >> 47);
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b *= mul;
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return b;
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}
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static uint64 HashLen0to16(const char* s, std::size_t len) {
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static u64 HashLen0to16(const char* s, size_t len) {
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if (len >= 8) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch64(s) + k2;
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uint64 b = Fetch64(s + len - 8);
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uint64 c = Rotate(b, 37) * mul + a;
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uint64 d = (Rotate(a, 25) + b) * mul;
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u64 mul = k2 + len * 2;
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u64 a = Fetch64(s) + k2;
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u64 b = Fetch64(s + len - 8);
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u64 c = Rotate(b, 37) * mul + a;
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u64 d = (Rotate(a, 25) + b) * mul;
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return HashLen16(c, d, mul);
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}
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if (len >= 4) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch32(s);
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u64 mul = k2 + len * 2;
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u64 a = Fetch32(s);
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return HashLen16(len + (a << 3), Fetch32(s + len - 4), mul);
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}
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if (len > 0) {
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uint8 a = s[0];
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uint8 b = s[len >> 1];
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uint8 c = s[len - 1];
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uint32 y = static_cast<uint32>(a) + (static_cast<uint32>(b) << 8);
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uint32 z = static_cast<uint32>(len) + (static_cast<uint32>(c) << 2);
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u8 a = s[0];
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u8 b = s[len >> 1];
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u8 c = s[len - 1];
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u32 y = static_cast<u32>(a) + (static_cast<u32>(b) << 8);
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u32 z = static_cast<u32>(len) + (static_cast<u32>(c) << 2);
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return ShiftMix(y * k2 ^ z * k0) * k2;
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}
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return k2;
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@ -141,22 +139,21 @@ static uint64 HashLen0to16(const char* s, std::size_t len) {
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// This probably works well for 16-byte strings as well, but it may be overkill
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// in that case.
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static uint64 HashLen17to32(const char* s, std::size_t len) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch64(s) * k1;
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uint64 b = Fetch64(s + 8);
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uint64 c = Fetch64(s + len - 8) * mul;
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uint64 d = Fetch64(s + len - 16) * k2;
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static u64 HashLen17to32(const char* s, size_t len) {
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u64 mul = k2 + len * 2;
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u64 a = Fetch64(s) * k1;
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u64 b = Fetch64(s + 8);
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u64 c = Fetch64(s + len - 8) * mul;
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u64 d = Fetch64(s + len - 16) * k2;
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return HashLen16(Rotate(a + b, 43) + Rotate(c, 30) + d, a + Rotate(b + k2, 18) + c, mul);
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}
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// Return a 16-byte hash for 48 bytes. Quick and dirty.
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// Callers do best to use "random-looking" values for a and b.
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static pair<uint64, uint64> WeakHashLen32WithSeeds(uint64 w, uint64 x, uint64 y, uint64 z, uint64 a,
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uint64 b) {
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static pair<u64, u64> WeakHashLen32WithSeeds(u64 w, u64 x, u64 y, u64 z, u64 a, u64 b) {
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a += w;
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b = Rotate(b + a + z, 21);
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uint64 c = a;
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u64 c = a;
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a += x;
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a += y;
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b += Rotate(a, 44);
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@ -164,34 +161,34 @@ static pair<uint64, uint64> WeakHashLen32WithSeeds(uint64 w, uint64 x, uint64 y,
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}
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// Return a 16-byte hash for s[0] ... s[31], a, and b. Quick and dirty.
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static pair<uint64, uint64> WeakHashLen32WithSeeds(const char* s, uint64 a, uint64 b) {
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static pair<u64, u64> WeakHashLen32WithSeeds(const char* s, u64 a, u64 b) {
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return WeakHashLen32WithSeeds(Fetch64(s), Fetch64(s + 8), Fetch64(s + 16), Fetch64(s + 24), a,
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b);
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}
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// Return an 8-byte hash for 33 to 64 bytes.
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static uint64 HashLen33to64(const char* s, std::size_t len) {
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uint64 mul = k2 + len * 2;
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uint64 a = Fetch64(s) * k2;
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uint64 b = Fetch64(s + 8);
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uint64 c = Fetch64(s + len - 24);
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uint64 d = Fetch64(s + len - 32);
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uint64 e = Fetch64(s + 16) * k2;
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uint64 f = Fetch64(s + 24) * 9;
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uint64 g = Fetch64(s + len - 8);
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uint64 h = Fetch64(s + len - 16) * mul;
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uint64 u = Rotate(a + g, 43) + (Rotate(b, 30) + c) * 9;
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uint64 v = ((a + g) ^ d) + f + 1;
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uint64 w = swap64((u + v) * mul) + h;
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uint64 x = Rotate(e + f, 42) + c;
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uint64 y = (swap64((v + w) * mul) + g) * mul;
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uint64 z = e + f + c;
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static u64 HashLen33to64(const char* s, size_t len) {
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u64 mul = k2 + len * 2;
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u64 a = Fetch64(s) * k2;
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u64 b = Fetch64(s + 8);
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u64 c = Fetch64(s + len - 24);
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u64 d = Fetch64(s + len - 32);
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u64 e = Fetch64(s + 16) * k2;
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u64 f = Fetch64(s + 24) * 9;
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u64 g = Fetch64(s + len - 8);
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u64 h = Fetch64(s + len - 16) * mul;
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u64 u = Rotate(a + g, 43) + (Rotate(b, 30) + c) * 9;
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u64 v = ((a + g) ^ d) + f + 1;
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u64 w = swap64((u + v) * mul) + h;
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u64 x = Rotate(e + f, 42) + c;
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u64 y = (swap64((v + w) * mul) + g) * mul;
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u64 z = e + f + c;
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a = swap64((x + z) * mul + y) + b;
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b = ShiftMix((z + a) * mul + d + h) * mul;
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return b + x;
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}
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uint64 CityHash64(const char* s, std::size_t len) {
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u64 CityHash64(const char* s, size_t len) {
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if (len <= 32) {
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if (len <= 16) {
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return HashLen0to16(s, len);
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@ -204,15 +201,15 @@ uint64 CityHash64(const char* s, std::size_t len) {
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// For strings over 64 bytes we hash the end first, and then as we
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// loop we keep 56 bytes of state: v, w, x, y, and z.
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uint64 x = Fetch64(s + len - 40);
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uint64 y = Fetch64(s + len - 16) + Fetch64(s + len - 56);
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uint64 z = HashLen16(Fetch64(s + len - 48) + len, Fetch64(s + len - 24));
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pair<uint64, uint64> v = WeakHashLen32WithSeeds(s + len - 64, len, z);
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pair<uint64, uint64> w = WeakHashLen32WithSeeds(s + len - 32, y + k1, x);
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u64 x = Fetch64(s + len - 40);
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u64 y = Fetch64(s + len - 16) + Fetch64(s + len - 56);
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u64 z = HashLen16(Fetch64(s + len - 48) + len, Fetch64(s + len - 24));
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pair<u64, u64> v = WeakHashLen32WithSeeds(s + len - 64, len, z);
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pair<u64, u64> w = WeakHashLen32WithSeeds(s + len - 32, y + k1, x);
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x = x * k1 + Fetch64(s);
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// Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
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len = (len - 1) & ~static_cast<std::size_t>(63);
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len = (len - 1) & ~static_cast<size_t>(63);
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do {
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x = Rotate(x + y + v.first + Fetch64(s + 8), 37) * k1;
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y = Rotate(y + v.second + Fetch64(s + 48), 42) * k1;
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@ -229,21 +226,21 @@ uint64 CityHash64(const char* s, std::size_t len) {
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HashLen16(v.second, w.second) + x);
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}
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uint64 CityHash64WithSeed(const char* s, std::size_t len, uint64 seed) {
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u64 CityHash64WithSeed(const char* s, size_t len, u64 seed) {
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return CityHash64WithSeeds(s, len, k2, seed);
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}
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uint64 CityHash64WithSeeds(const char* s, std::size_t len, uint64 seed0, uint64 seed1) {
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u64 CityHash64WithSeeds(const char* s, size_t len, u64 seed0, u64 seed1) {
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return HashLen16(CityHash64(s, len) - seed0, seed1);
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}
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// A subroutine for CityHash128(). Returns a decent 128-bit hash for strings
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// of any length representable in signed long. Based on City and Murmur.
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static uint128 CityMurmur(const char* s, std::size_t len, uint128 seed) {
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uint64 a = Uint128Low64(seed);
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uint64 b = Uint128High64(seed);
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uint64 c = 0;
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uint64 d = 0;
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static u128 CityMurmur(const char* s, size_t len, u128 seed) {
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u64 a = seed[0];
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u64 b = seed[1];
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u64 c = 0;
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u64 d = 0;
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signed long l = static_cast<long>(len) - 16;
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if (l <= 0) { // len <= 16
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a = ShiftMix(a * k1) * k1;
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@ -266,20 +263,20 @@ static uint128 CityMurmur(const char* s, std::size_t len, uint128 seed) {
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}
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a = HashLen16(a, c);
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b = HashLen16(d, b);
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return uint128(a ^ b, HashLen16(b, a));
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return u128{a ^ b, HashLen16(b, a)};
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}
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uint128 CityHash128WithSeed(const char* s, std::size_t len, uint128 seed) {
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u128 CityHash128WithSeed(const char* s, size_t len, u128 seed) {
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if (len < 128) {
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return CityMurmur(s, len, seed);
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}
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// We expect len >= 128 to be the common case. Keep 56 bytes of state:
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// v, w, x, y, and z.
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pair<uint64, uint64> v, w;
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uint64 x = Uint128Low64(seed);
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uint64 y = Uint128High64(seed);
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uint64 z = len * k1;
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pair<u64, u64> v, w;
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u64 x = seed[0];
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u64 y = seed[1];
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u64 z = len * k1;
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v.first = Rotate(y ^ k1, 49) * k1 + Fetch64(s);
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v.second = Rotate(v.first, 42) * k1 + Fetch64(s + 8);
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w.first = Rotate(y + z, 35) * k1 + x;
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@ -313,7 +310,7 @@ uint128 CityHash128WithSeed(const char* s, std::size_t len, uint128 seed) {
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w.first *= 9;
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v.first *= k0;
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// If 0 < len < 128, hash up to 4 chunks of 32 bytes each from the end of s.
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for (std::size_t tail_done = 0; tail_done < len;) {
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for (size_t tail_done = 0; tail_done < len;) {
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tail_done += 32;
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y = Rotate(x + y, 42) * k0 + v.second;
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w.first += Fetch64(s + len - tail_done + 16);
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@ -328,13 +325,12 @@ uint128 CityHash128WithSeed(const char* s, std::size_t len, uint128 seed) {
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// different 56-byte-to-8-byte hashes to get a 16-byte final result.
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x = HashLen16(x, v.first);
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y = HashLen16(y + z, w.first);
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return uint128(HashLen16(x + v.second, w.second) + y, HashLen16(x + w.second, y + v.second));
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return u128{HashLen16(x + v.second, w.second) + y, HashLen16(x + w.second, y + v.second)};
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}
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uint128 CityHash128(const char* s, std::size_t len) {
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return len >= 16
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? CityHash128WithSeed(s + 16, len - 16, uint128(Fetch64(s), Fetch64(s + 8) + k0))
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: CityHash128WithSeed(s, len, uint128(k0, k1));
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u128 CityHash128(const char* s, size_t len) {
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return len >= 16 ? CityHash128WithSeed(s + 16, len - 16, u128{Fetch64(s), Fetch64(s + 8) + k0})
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: CityHash128WithSeed(s, len, u128{k0, k1});
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}
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} // namespace Common
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@ -61,50 +61,38 @@
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#pragma once
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#include <cstddef>
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#include <cstdint>
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#include <utility>
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#include "common/common_types.h"
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namespace Common {
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using uint128 = std::pair<uint64_t, uint64_t>;
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[[nodiscard]] inline uint64_t Uint128Low64(const uint128& x) {
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return x.first;
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}
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[[nodiscard]] inline uint64_t Uint128High64(const uint128& x) {
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return x.second;
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}
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// Hash function for a byte array.
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[[nodiscard]] uint64_t CityHash64(const char* buf, std::size_t len);
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[[nodiscard]] u64 CityHash64(const char* buf, size_t len);
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// Hash function for a byte array. For convenience, a 64-bit seed is also
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// hashed into the result.
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[[nodiscard]] uint64_t CityHash64WithSeed(const char* buf, std::size_t len, uint64_t seed);
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[[nodiscard]] u64 CityHash64WithSeed(const char* buf, size_t len, u64 seed);
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// Hash function for a byte array. For convenience, two seeds are also
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// hashed into the result.
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[[nodiscard]] uint64_t CityHash64WithSeeds(const char* buf, std::size_t len, uint64_t seed0,
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uint64_t seed1);
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[[nodiscard]] u64 CityHash64WithSeeds(const char* buf, size_t len, u64 seed0, u64 seed1);
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// Hash function for a byte array.
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[[nodiscard]] uint128 CityHash128(const char* s, std::size_t len);
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[[nodiscard]] u128 CityHash128(const char* s, size_t len);
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// Hash function for a byte array. For convenience, a 128-bit seed is also
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// hashed into the result.
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[[nodiscard]] uint128 CityHash128WithSeed(const char* s, std::size_t len, uint128 seed);
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[[nodiscard]] u128 CityHash128WithSeed(const char* s, size_t len, u128 seed);
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// Hash 128 input bits down to 64 bits of output.
|
||||
// This is intended to be a reasonably good hash function.
|
||||
[[nodiscard]] inline uint64_t Hash128to64(const uint128& x) {
|
||||
[[nodiscard]] inline u64 Hash128to64(const u128& x) {
|
||||
// Murmur-inspired hashing.
|
||||
const uint64_t kMul = 0x9ddfea08eb382d69ULL;
|
||||
uint64_t a = (Uint128Low64(x) ^ Uint128High64(x)) * kMul;
|
||||
const u64 mul = 0x9ddfea08eb382d69ULL;
|
||||
u64 a = (x[0] ^ x[1]) * mul;
|
||||
a ^= (a >> 47);
|
||||
uint64_t b = (Uint128High64(x) ^ a) * kMul;
|
||||
u64 b = (x[1] ^ a) * mul;
|
||||
b ^= (b >> 47);
|
||||
b *= kMul;
|
||||
b *= mul;
|
||||
return b;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -16,7 +16,7 @@ TEST_CASE("CityHash", "[common]") {
|
|||
REQUIRE(CityHash64(msg, sizeof(msg)) == 0x92d5c2e9cbfbbc01);
|
||||
REQUIRE(CityHash64WithSeed(msg, sizeof(msg), 0xdead) == 0xbfbe93f21a2820dd);
|
||||
REQUIRE(CityHash64WithSeeds(msg, sizeof(msg), 0xbeef, 0xcafe) == 0xb343317955fc8a06);
|
||||
REQUIRE(CityHash128(msg, sizeof(msg)) == uint128{0x98e60d0423747eaa, 0xd8694c5b6fcaede9});
|
||||
REQUIRE(CityHash128(msg, sizeof(msg)) == u128{0x98e60d0423747eaa, 0xd8694c5b6fcaede9});
|
||||
REQUIRE(CityHash128WithSeed(msg, sizeof(msg), {0xdead, 0xbeef}) ==
|
||||
uint128{0xf0307dba81199ebe, 0xd77764e0c4a9eb74});
|
||||
u128{0xf0307dba81199ebe, 0xd77764e0c4a9eb74});
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in a new issue