mirror of
https://github.com/XTLS/Xray-core.git
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302 lines
6.9 KiB
Go
302 lines
6.9 KiB
Go
package strmatcher
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import (
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"math/bits"
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"regexp"
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"sort"
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"strings"
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"unsafe"
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)
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// PrimeRK is the prime base used in Rabin-Karp algorithm.
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const PrimeRK = 16777619
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// calculate the rolling murmurHash of given string
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func RollingHash(s string) uint32 {
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h := uint32(0)
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for i := len(s) - 1; i >= 0; i-- {
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h = h*PrimeRK + uint32(s[i])
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}
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return h
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}
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// A MphMatcherGroup is divided into three parts:
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// 1. `full` and `domain` patterns are matched by Rabin-Karp algorithm and minimal perfect hash table;
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// 2. `substr` patterns are matched by ac automaton;
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// 3. `regex` patterns are matched with the regex library.
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type MphMatcherGroup struct {
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ac *ACAutomaton
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otherMatchers []matcherEntry
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rules []string
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level0 []uint32
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level0Mask int
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level1 []uint32
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level1Mask int
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count uint32
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ruleMap *map[string]uint32
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}
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func (g *MphMatcherGroup) AddFullOrDomainPattern(pattern string, t Type) {
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h := RollingHash(pattern)
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switch t {
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case Domain:
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(*g.ruleMap)["."+pattern] = h*PrimeRK + uint32('.')
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fallthrough
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case Full:
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(*g.ruleMap)[pattern] = h
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default:
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}
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}
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func NewMphMatcherGroup() *MphMatcherGroup {
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return &MphMatcherGroup{
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ac: nil,
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otherMatchers: nil,
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rules: nil,
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level0: nil,
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level0Mask: 0,
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level1: nil,
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level1Mask: 0,
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count: 1,
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ruleMap: &map[string]uint32{},
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}
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}
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// AddPattern adds a pattern to MphMatcherGroup
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func (g *MphMatcherGroup) AddPattern(pattern string, t Type) (uint32, error) {
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switch t {
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case Substr:
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if g.ac == nil {
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g.ac = NewACAutomaton()
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}
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g.ac.Add(pattern, t)
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case Full, Domain:
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pattern = strings.ToLower(pattern)
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g.AddFullOrDomainPattern(pattern, t)
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case Regex:
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r, err := regexp.Compile(pattern)
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if err != nil {
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return 0, err
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}
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g.otherMatchers = append(g.otherMatchers, matcherEntry{
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m: ®exMatcher{pattern: r},
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id: g.count,
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})
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default:
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panic("Unknown type")
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}
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return g.count, nil
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}
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// Build builds a minimal perfect hash table and ac automaton from insert rules
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func (g *MphMatcherGroup) Build() {
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if g.ac != nil {
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g.ac.Build()
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}
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keyLen := len(*g.ruleMap)
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if keyLen == 0 {
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keyLen = 1
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(*g.ruleMap)["empty___"] = RollingHash("empty___")
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}
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g.level0 = make([]uint32, nextPow2(keyLen/4))
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g.level0Mask = len(g.level0) - 1
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g.level1 = make([]uint32, nextPow2(keyLen))
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g.level1Mask = len(g.level1) - 1
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var sparseBuckets = make([][]int, len(g.level0))
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var ruleIdx int
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for rule, hash := range *g.ruleMap {
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n := int(hash) & g.level0Mask
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g.rules = append(g.rules, rule)
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sparseBuckets[n] = append(sparseBuckets[n], ruleIdx)
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ruleIdx++
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}
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g.ruleMap = nil
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var buckets []indexBucket
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for n, vals := range sparseBuckets {
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if len(vals) > 0 {
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buckets = append(buckets, indexBucket{n, vals})
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}
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}
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sort.Sort(bySize(buckets))
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occ := make([]bool, len(g.level1))
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var tmpOcc []int
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for _, bucket := range buckets {
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var seed = uint32(0)
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for {
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findSeed := true
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tmpOcc = tmpOcc[:0]
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for _, i := range bucket.vals {
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n := int(strhashFallback(unsafe.Pointer(&g.rules[i]), uintptr(seed))) & g.level1Mask
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if occ[n] {
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for _, n := range tmpOcc {
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occ[n] = false
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}
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seed++
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findSeed = false
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break
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}
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occ[n] = true
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tmpOcc = append(tmpOcc, n)
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g.level1[n] = uint32(i)
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}
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if findSeed {
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g.level0[bucket.n] = seed
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break
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}
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}
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}
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}
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func nextPow2(v int) int {
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if v <= 1 {
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return 1
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}
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const MaxUInt = ^uint(0)
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n := (MaxUInt >> bits.LeadingZeros(uint(v))) + 1
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return int(n)
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}
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// Lookup searches for s in t and returns its index and whether it was found.
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func (g *MphMatcherGroup) Lookup(h uint32, s string) bool {
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i0 := int(h) & g.level0Mask
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seed := g.level0[i0]
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i1 := int(strhashFallback(unsafe.Pointer(&s), uintptr(seed))) & g.level1Mask
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n := g.level1[i1]
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return s == g.rules[int(n)]
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}
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// Match implements IndexMatcher.Match.
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func (g *MphMatcherGroup) Match(pattern string) []uint32 {
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result := []uint32{}
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hash := uint32(0)
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for i := len(pattern) - 1; i >= 0; i-- {
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hash = hash*PrimeRK + uint32(pattern[i])
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if pattern[i] == '.' {
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if g.Lookup(hash, pattern[i:]) {
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result = append(result, 1)
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return result
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}
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}
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}
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if g.Lookup(hash, pattern) {
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result = append(result, 1)
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return result
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}
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if g.ac != nil && g.ac.Match(pattern) {
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result = append(result, 1)
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return result
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}
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for _, e := range g.otherMatchers {
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if e.m.Match(pattern) {
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result = append(result, e.id)
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return result
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}
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}
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return nil
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}
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type indexBucket struct {
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n int
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vals []int
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}
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type bySize []indexBucket
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func (s bySize) Len() int { return len(s) }
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func (s bySize) Less(i, j int) bool { return len(s[i].vals) > len(s[j].vals) }
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func (s bySize) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
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type stringStruct struct {
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str unsafe.Pointer
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len int
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}
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func strhashFallback(a unsafe.Pointer, h uintptr) uintptr {
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x := (*stringStruct)(a)
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return memhashFallback(x.str, h, uintptr(x.len))
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}
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const (
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// Constants for multiplication: four random odd 64-bit numbers.
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m1 = 16877499708836156737
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m2 = 2820277070424839065
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m3 = 9497967016996688599
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m4 = 15839092249703872147
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)
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var hashkey = [4]uintptr{1, 1, 1, 1}
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func memhashFallback(p unsafe.Pointer, seed, s uintptr) uintptr {
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h := uint64(seed + s*hashkey[0])
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tail:
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switch {
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case s == 0:
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case s < 4:
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h ^= uint64(*(*byte)(p))
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h ^= uint64(*(*byte)(add(p, s>>1))) << 8
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h ^= uint64(*(*byte)(add(p, s-1))) << 16
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h = rotl31(h*m1) * m2
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case s <= 8:
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h ^= uint64(readUnaligned32(p))
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h ^= uint64(readUnaligned32(add(p, s-4))) << 32
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h = rotl31(h*m1) * m2
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case s <= 16:
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h ^= readUnaligned64(p)
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h = rotl31(h*m1) * m2
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h ^= readUnaligned64(add(p, s-8))
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h = rotl31(h*m1) * m2
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case s <= 32:
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h ^= readUnaligned64(p)
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h = rotl31(h*m1) * m2
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h ^= readUnaligned64(add(p, 8))
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h = rotl31(h*m1) * m2
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h ^= readUnaligned64(add(p, s-16))
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h = rotl31(h*m1) * m2
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h ^= readUnaligned64(add(p, s-8))
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h = rotl31(h*m1) * m2
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default:
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v1 := h
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v2 := uint64(seed * hashkey[1])
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v3 := uint64(seed * hashkey[2])
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v4 := uint64(seed * hashkey[3])
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for s >= 32 {
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v1 ^= readUnaligned64(p)
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v1 = rotl31(v1*m1) * m2
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p = add(p, 8)
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v2 ^= readUnaligned64(p)
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v2 = rotl31(v2*m2) * m3
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p = add(p, 8)
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v3 ^= readUnaligned64(p)
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v3 = rotl31(v3*m3) * m4
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p = add(p, 8)
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v4 ^= readUnaligned64(p)
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v4 = rotl31(v4*m4) * m1
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p = add(p, 8)
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s -= 32
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}
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h = v1 ^ v2 ^ v3 ^ v4
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goto tail
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}
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h ^= h >> 29
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h *= m3
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h ^= h >> 32
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return uintptr(h)
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}
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func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
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return unsafe.Pointer(uintptr(p) + x)
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}
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func readUnaligned32(p unsafe.Pointer) uint32 {
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q := (*[4]byte)(p)
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return uint32(q[0]) | uint32(q[1])<<8 | uint32(q[2])<<16 | uint32(q[3])<<24
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}
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func rotl31(x uint64) uint64 {
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return (x << 31) | (x >> (64 - 31))
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}
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func readUnaligned64(p unsafe.Pointer) uint64 {
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q := (*[8]byte)(p)
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return uint64(q[0]) | uint64(q[1])<<8 | uint64(q[2])<<16 | uint64(q[3])<<24 | uint64(q[4])<<32 | uint64(q[5])<<40 | uint64(q[6])<<48 | uint64(q[7])<<56
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}
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