dolphin/Source/Core/Common/Hash.cpp

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// Copyright 2008 Dolphin Emulator Project
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// Licensed under GPLv2+
// Refer to the license.txt file included.
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#include "Common/Hash.h"
#include <algorithm>
#include <cstring>
#include "Common/BitUtils.h"
#include "Common/CPUDetect.h"
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#include "Common/CommonFuncs.h"
#include "Common/Intrinsics.h"
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#ifdef _M_ARM_64
#ifdef _MSC_VER
#include <intrin.h>
#else
#include <arm_acle.h>
#endif
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#endif
namespace Common
{
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static u64 (*ptrHashFunction)(const u8* src, u32 len, u32 samples) = nullptr;
// uint32_t
// WARNING - may read one more byte!
// Implementation from Wikipedia.
u32 HashFletcher(const u8* data_u8, size_t length)
{
const u16* data = (const u16*)data_u8; /* Pointer to the data to be summed */
size_t len = (length + 1) / 2; /* Length in 16-bit words */
u32 sum1 = 0xffff, sum2 = 0xffff;
while (len)
{
size_t tlen = len > 360 ? 360 : len;
len -= tlen;
do
{
sum1 += *data++;
sum2 += sum1;
} while (--tlen);
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
}
// Second reduction step to reduce sums to 16 bits
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
return (sum2 << 16 | sum1);
}
// Implementation from Wikipedia
// Slightly slower than Fletcher above, but slightly more reliable.
// data: Pointer to the data to be summed; len is in bytes
u32 HashAdler32(const u8* data, size_t len)
{
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static const u32 MOD_ADLER = 65521;
u32 a = 1, b = 0;
while (len)
{
size_t tlen = len > 5550 ? 5550 : len;
len -= tlen;
do
{
a += *data++;
b += a;
} while (--tlen);
a = (a & 0xffff) + (a >> 16) * (65536 - MOD_ADLER);
b = (b & 0xffff) + (b >> 16) * (65536 - MOD_ADLER);
}
// It can be shown that a <= 0x1013a here, so a single subtract will do.
if (a >= MOD_ADLER)
{
a -= MOD_ADLER;
}
// It can be shown that b can reach 0xfff87 here.
b = (b & 0xffff) + (b >> 16) * (65536 - MOD_ADLER);
if (b >= MOD_ADLER)
{
b -= MOD_ADLER;
}
return ((b << 16) | a);
}
// Stupid hash - but can't go back now :)
// Don't use for new things. At least it's reasonably fast.
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u32 HashEctor(const u8* ptr, size_t length)
{
u32 crc = 0;
for (int i = 0; i < length; i++)
{
crc ^= ptr[i];
crc = (crc << 3) | (crc >> 29);
}
return (crc);
}
#if _ARCH_64
//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here
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static u64 getblock(const u64* p, int i)
{
return p[i];
}
//----------
// Block mix - combine the key bits with the hash bits and scramble everything
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static void bmix64(u64& h1, u64& h2, u64& k1, u64& k2, u64& c1, u64& c2)
{
k1 *= c1;
k1 = Common::RotateLeft(k1, 23);
k1 *= c2;
h1 ^= k1;
h1 += h2;
h2 = Common::RotateLeft(h2, 41);
k2 *= c2;
k2 = Common::RotateLeft(k2, 23);
k2 *= c1;
h2 ^= k2;
h2 += h1;
h1 = h1 * 3 + 0x52dce729;
h2 = h2 * 3 + 0x38495ab5;
c1 = c1 * 5 + 0x7b7d159c;
c2 = c2 * 5 + 0x6bce6396;
}
//----------
// Finalization mix - avalanches all bits to within 0.05% bias
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static u64 fmix64(u64 k)
{
k ^= k >> 33;
k *= 0xff51afd7ed558ccd;
k ^= k >> 33;
k *= 0xc4ceb9fe1a85ec53;
k ^= k >> 33;
return k;
}
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static u64 GetMurmurHash3(const u8* src, u32 len, u32 samples)
{
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const u8* data = (const u8*)src;
const int nblocks = len / 16;
u32 Step = (len / 8);
if (samples == 0)
samples = std::max(Step, 1u);
Step = Step / samples;
if (Step < 1)
Step = 1;
u64 h1 = 0x9368e53c2f6af274;
u64 h2 = 0x586dcd208f7cd3fd;
u64 c1 = 0x87c37b91114253d5;
u64 c2 = 0x4cf5ad432745937f;
//----------
// body
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const u64* blocks = (const u64*)(data);
for (int i = 0; i < nblocks; i += Step)
{
u64 k1 = getblock(blocks, i * 2 + 0);
u64 k2 = getblock(blocks, i * 2 + 1);
bmix64(h1, h2, k1, k2, c1, c2);
}
//----------
// tail
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const u8* tail = (const u8*)(data + nblocks * 16);
u64 k1 = 0;
u64 k2 = 0;
switch (len & 15)
{
case 15:
k2 ^= u64(tail[14]) << 48;
case 14:
k2 ^= u64(tail[13]) << 40;
case 13:
k2 ^= u64(tail[12]) << 32;
case 12:
k2 ^= u64(tail[11]) << 24;
case 11:
k2 ^= u64(tail[10]) << 16;
case 10:
k2 ^= u64(tail[9]) << 8;
case 9:
k2 ^= u64(tail[8]) << 0;
case 8:
k1 ^= u64(tail[7]) << 56;
case 7:
k1 ^= u64(tail[6]) << 48;
case 6:
k1 ^= u64(tail[5]) << 40;
case 5:
k1 ^= u64(tail[4]) << 32;
case 4:
k1 ^= u64(tail[3]) << 24;
case 3:
k1 ^= u64(tail[2]) << 16;
case 2:
k1 ^= u64(tail[1]) << 8;
case 1:
k1 ^= u64(tail[0]) << 0;
bmix64(h1, h2, k1, k2, c1, c2);
};
//----------
// finalization
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix64(h1);
h2 = fmix64(h2);
h1 += h2;
return h1;
}
// CRC32 hash using the SSE4.2 instruction
#if defined(_M_X86_64)
FUNCTION_TARGET_SSE42
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static u64 GetCRC32(const u8* src, u32 len, u32 samples)
{
u64 h[4] = {len, 0, 0, 0};
u32 Step = (len / 8);
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const u64* data = (const u64*)src;
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const u64* end = data + Step;
if (samples == 0)
samples = std::max(Step, 1u);
Step = Step / samples;
if (Step < 1)
Step = 1;
while (data < end - Step * 3)
{
h[0] = _mm_crc32_u64(h[0], data[Step * 0]);
h[1] = _mm_crc32_u64(h[1], data[Step * 1]);
h[2] = _mm_crc32_u64(h[2], data[Step * 2]);
h[3] = _mm_crc32_u64(h[3], data[Step * 3]);
data += Step * 4;
}
if (data < end - Step * 0)
h[0] = _mm_crc32_u64(h[0], data[Step * 0]);
if (data < end - Step * 1)
h[1] = _mm_crc32_u64(h[1], data[Step * 1]);
if (data < end - Step * 2)
h[2] = _mm_crc32_u64(h[2], data[Step * 2]);
if (len & 7)
{
u64 temp = 0;
memcpy(&temp, end, len & 7);
h[0] = _mm_crc32_u64(h[0], temp);
}
// FIXME: is there a better way to combine these partial hashes?
return h[0] + (h[1] << 10) + (h[2] << 21) + (h[3] << 32);
}
#elif defined(_M_ARM_64)
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static u64 GetCRC32(const u8* src, u32 len, u32 samples)
{
u64 h[4] = {len, 0, 0, 0};
u32 Step = (len / 8);
const u64* data = (const u64*)src;
const u64* end = data + Step;
if (samples == 0)
samples = std::max(Step, 1u);
Step = Step / samples;
if (Step < 1)
Step = 1;
while (data < end - Step * 3)
{
h[0] = __crc32d(h[0], data[Step * 0]);
h[1] = __crc32d(h[1], data[Step * 1]);
h[2] = __crc32d(h[2], data[Step * 2]);
h[3] = __crc32d(h[3], data[Step * 3]);
data += Step * 4;
}
if (data < end - Step * 0)
h[0] = __crc32d(h[0], data[Step * 0]);
if (data < end - Step * 1)
h[1] = __crc32d(h[1], data[Step * 1]);
if (data < end - Step * 2)
h[2] = __crc32d(h[2], data[Step * 2]);
if (len & 7)
{
u64 temp = 0;
memcpy(&temp, end, len & 7);
h[0] = __crc32d(h[0], temp);
}
// FIXME: is there a better way to combine these partial hashes?
return h[0] + (h[1] << 10) + (h[2] << 21) + (h[3] << 32);
}
#else
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static u64 GetCRC32(const u8* src, u32 len, u32 samples)
{
return 0;
}
#endif
#else
// CRC32 hash using the SSE4.2 instruction
#if defined(_M_X86)
FUNCTION_TARGET_SSE42
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static u64 GetCRC32(const u8* src, u32 len, u32 samples)
{
u32 h = len;
u32 Step = (len / 4);
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const u32* data = (const u32*)src;
const u32* end = data + Step;
if (samples == 0)
samples = std::max(Step, 1u);
Step = Step / samples;
if (Step < 1)
Step = 1;
while (data < end)
{
h = _mm_crc32_u32(h, data[0]);
data += Step;
}
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const u8* data2 = (const u8*)end;
return (u64)_mm_crc32_u32(h, u32(data2[0]));
}
#else
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static u64 GetCRC32(const u8* src, u32 len, u32 samples)
{
return 0;
}
#endif
//-----------------------------------------------------------------------------
// Block read - if your platform needs to do endian-swapping or can only
// handle aligned reads, do the conversion here
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static u32 getblock(const u32* p, int i)
{
return p[i];
}
//----------
// Finalization mix - force all bits of a hash block to avalanche
// avalanches all bits to within 0.25% bias
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static u32 fmix32(u32 h)
{
h ^= h >> 16;
h *= 0x85ebca6b;
h ^= h >> 13;
h *= 0xc2b2ae35;
h ^= h >> 16;
return h;
}
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static void bmix32(u32& h1, u32& h2, u32& k1, u32& k2, u32& c1, u32& c2)
{
k1 *= c1;
k1 = Common::RotateLeft(k1, 11);
k1 *= c2;
h1 ^= k1;
h1 += h2;
h2 = Common::RotateLeft(h2, 17);
k2 *= c2;
k2 = Common::RotateLeft(k2, 11);
k2 *= c1;
h2 ^= k2;
h2 += h1;
h1 = h1 * 3 + 0x52dce729;
h2 = h2 * 3 + 0x38495ab5;
c1 = c1 * 5 + 0x7b7d159c;
c2 = c2 * 5 + 0x6bce6396;
}
//----------
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static u64 GetMurmurHash3(const u8* src, u32 len, u32 samples)
{
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const u8* data = (const u8*)src;
u32 out[2];
const int nblocks = len / 8;
u32 Step = (len / 4);
if (samples == 0)
samples = std::max(Step, 1u);
Step = Step / samples;
if (Step < 1)
Step = 1;
u32 h1 = 0x8de1c3ac;
u32 h2 = 0xbab98226;
u32 c1 = 0x95543787;
u32 c2 = 0x2ad7eb25;
//----------
// body
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const u32* blocks = (const u32*)(data + nblocks * 8);
for (int i = -nblocks; i < 0; i += Step)
{
u32 k1 = getblock(blocks, i * 2 + 0);
u32 k2 = getblock(blocks, i * 2 + 1);
bmix32(h1, h2, k1, k2, c1, c2);
}
//----------
// tail
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const u8* tail = (const u8*)(data + nblocks * 8);
u32 k1 = 0;
u32 k2 = 0;
switch (len & 7)
{
case 7:
k2 ^= tail[6] << 16;
case 6:
k2 ^= tail[5] << 8;
case 5:
k2 ^= tail[4] << 0;
case 4:
k1 ^= tail[3] << 24;
case 3:
k1 ^= tail[2] << 16;
case 2:
k1 ^= tail[1] << 8;
case 1:
k1 ^= tail[0] << 0;
bmix32(h1, h2, k1, k2, c1, c2);
};
//----------
// finalization
h2 ^= len;
h1 += h2;
h2 += h1;
h1 = fmix32(h1);
h2 = fmix32(h2);
h1 += h2;
h2 += h1;
out[0] = h1;
out[1] = h2;
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return *((u64*)&out);
}
#endif
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u64 GetHash64(const u8* src, u32 len, u32 samples)
{
return ptrHashFunction(src, len, samples);
}
// sets the hash function used for the texture cache
void SetHash64Function()
{
#if defined(_M_X86_64) || defined(_M_X86)
if (cpu_info.bSSE4_2) // sse crc32 version
{
ptrHashFunction = &GetCRC32;
}
else
#elif defined(_M_ARM_64)
if (cpu_info.bCRC32)
{
ptrHashFunction = &GetCRC32;
}
else
#endif
{
ptrHashFunction = &GetMurmurHash3;
}
}
} // namespace Common