Hein
41 lines
969 B
Go
41 lines
969 B
Go
package keyset
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import (
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"bytes"
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"github.com/segmentio/asm/cpu"
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"github.com/segmentio/asm/cpu/arm64"
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"github.com/segmentio/asm/cpu/x86"
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)
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// New prepares a set of keys for use with Lookup.
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//
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// An optimized routine is used if the processor supports AVX instructions and
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// the maximum length of any of the keys is less than or equal to 16. If New
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// returns nil, this indicates that an optimized routine is not available, and
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// the caller should use a fallback.
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func New(keys [][]byte) []byte {
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maxWidth, hasNullByte := checkKeys(keys)
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if hasNullByte || maxWidth > 16 || !(cpu.X86.Has(x86.AVX) || cpu.ARM64.Has(arm64.ASIMD)) {
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return nil
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}
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set := make([]byte, len(keys)*16)
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for i, k := range keys {
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copy(set[i*16:], k)
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}
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return set
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}
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func checkKeys(keys [][]byte) (maxWidth int, hasNullByte bool) {
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for _, k := range keys {
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if len(k) > maxWidth {
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maxWidth = len(k)
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}
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if bytes.IndexByte(k, 0) >= 0 {
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hasNullByte = true
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}
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}
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return
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}
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