mirror of
https://github.com/superseriousbusiness/gotosocial
synced 2024-12-18 00:33:11 +00:00
129 lines
2.6 KiB
Go
129 lines
2.6 KiB
Go
package xxh3
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import (
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"math/bits"
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"unsafe"
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)
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// Uint128 is a 128 bit value.
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// The actual value can be thought of as u.Hi<<64 | u.Lo.
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type Uint128 struct {
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Hi, Lo uint64
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}
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// Bytes returns the uint128 as an array of bytes in canonical form (big-endian encoded).
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func (u Uint128) Bytes() [16]byte {
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return [16]byte{
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byte(u.Hi >> 0x38), byte(u.Hi >> 0x30), byte(u.Hi >> 0x28), byte(u.Hi >> 0x20),
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byte(u.Hi >> 0x18), byte(u.Hi >> 0x10), byte(u.Hi >> 0x08), byte(u.Hi),
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byte(u.Lo >> 0x38), byte(u.Lo >> 0x30), byte(u.Lo >> 0x28), byte(u.Lo >> 0x20),
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byte(u.Lo >> 0x18), byte(u.Lo >> 0x10), byte(u.Lo >> 0x08), byte(u.Lo),
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}
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}
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type (
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ptr = unsafe.Pointer
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ui = uintptr
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u8 = uint8
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u32 = uint32
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u64 = uint64
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u128 = Uint128
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)
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type str struct {
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p ptr
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l uint
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}
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func readU8(p ptr, o ui) uint8 {
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return *(*uint8)(ptr(ui(p) + o))
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}
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func readU16(p ptr, o ui) uint16 {
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b := (*[2]byte)(ptr(ui(p) + o))
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return uint16(b[0]) | uint16(b[1])<<8
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}
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func readU32(p ptr, o ui) uint32 {
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b := (*[4]byte)(ptr(ui(p) + o))
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return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
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}
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func readU64(p ptr, o ui) uint64 {
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b := (*[8]byte)(ptr(ui(p) + o))
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return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
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uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
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}
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func writeU64(p ptr, o ui, v u64) {
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b := (*[8]byte)(ptr(ui(p) + o))
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b[0] = byte(v)
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b[1] = byte(v >> 8)
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b[2] = byte(v >> 16)
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b[3] = byte(v >> 24)
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b[4] = byte(v >> 32)
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b[5] = byte(v >> 40)
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b[6] = byte(v >> 48)
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b[7] = byte(v >> 56)
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}
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const secretSize = 192
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func initSecret(secret ptr, seed u64) {
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for i := ui(0); i < secretSize/16; i++ {
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lo := readU64(key, 16*i) + seed
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hi := readU64(key, 16*i+8) - seed
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writeU64(secret, 16*i, lo)
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writeU64(secret, 16*i+8, hi)
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}
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}
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func xxh64AvalancheSmall(x u64) u64 {
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// x ^= x >> 33 // x must be < 32 bits
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// x ^= u64(key32_000 ^ key32_004) // caller must do this
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x *= prime64_2
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x ^= x >> 29
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x *= prime64_3
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x ^= x >> 32
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return x
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}
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func xxhAvalancheSmall(x u64) u64 {
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x ^= x >> 33
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x *= prime64_2
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x ^= x >> 29
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x *= prime64_3
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x ^= x >> 32
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return x
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}
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func xxh64AvalancheFull(x u64) u64 {
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x ^= x >> 33
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x *= prime64_2
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x ^= x >> 29
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x *= prime64_3
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x ^= x >> 32
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return x
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}
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func xxh3Avalanche(x u64) u64 {
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x ^= x >> 37
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x *= 0x165667919e3779f9
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x ^= x >> 32
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return x
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}
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func rrmxmx(h64 u64, len u64) u64 {
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h64 ^= bits.RotateLeft64(h64, 49) ^ bits.RotateLeft64(h64, 24)
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h64 *= 0x9fb21c651e98df25
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h64 ^= (h64 >> 35) + len
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h64 *= 0x9fb21c651e98df25
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h64 ^= (h64 >> 28)
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return h64
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}
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func mulFold64(x, y u64) u64 {
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hi, lo := bits.Mul64(x, y)
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return hi ^ lo
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}
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