97 lines
1.9 KiB
Go
97 lines
1.9 KiB
Go
package ecs
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import (
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"golang.org/x/exp/constraints"
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"math/bits"
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"unsafe"
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)
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const uintsize = uint(unsafe.Sizeof(BitSet{}.values[0]))
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type BitSet struct {
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// TODO: this is not a BitSet, I'm just testing
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values []uint
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}
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func (b *BitSet) Set(i Index) (old bool) {
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index := uint(i) / uintsize
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offset := uint(i) % uintsize
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if index >= uint(len(b.values)) {
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if index < uint(cap(b.values)) {
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b.values = b.values[:index]
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} else {
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newValues := make([]uint, index+1)
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copy(newValues, b.values)
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b.values = newValues
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}
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}
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v := &b.values[index]
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mask := uint(1 << offset)
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old = *v&mask != 0
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*v |= mask
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return
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}
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func (b *BitSet) Unset(i Index) (old bool) {
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index := uint(i) / uintsize
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offset := uint(i) % uintsize
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if index < uint(len(b.values)) {
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v := &b.values[index]
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mask := uint(1 << offset)
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old = *v&mask != 0
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*v &= ^mask
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}
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return
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}
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func (b *BitSet) Contains(i Index) bool {
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index := uint(i) / uintsize
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offset := uint(i) % uintsize
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return index < uint(len(b.values)) && b.values[index]&(1<<offset) != 0
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}
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func (b *BitSet) And(other *BitSet) *BitSet {
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result := BitSet{values: make([]uint, min(len(b.values), len(other.values)))}
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for i := range b.values {
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result.values[i] = b.values[i] & other.values[i]
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}
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return &result
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}
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func (b *BitSet) AndNot(other BitSet) *BitSet {
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result := BitSet{values: make([]uint, len(b.values))}
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for i := range b.values {
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if i < len(other.values) {
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result.values[i] = b.values[i] & ^other.values[i]
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} else {
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result.values[i] = b.values[i]
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}
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}
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return &result
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}
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func (b *BitSet) Range(f func(eid Index)) {
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for i, v := range b.values {
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base := int(unsafe.Sizeof(v)) * i
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for v != 0 {
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p := bits.TrailingZeros(v)
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f(Index(base + p))
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v ^= 1 << p
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}
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}
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}
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func max[T constraints.Integer](a, b T) T {
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if a > b {
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return a
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}
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return b
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}
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func min[T constraints.Integer](a, b T) T {
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if a < b {
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return a
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}
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return b
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}
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