42 lines
816 B
Go
42 lines
816 B
Go
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package bits
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// DecodeZigZag decodes a ZigZag encoded integer and returns it.
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//
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// Examples of ZigZag encoded values on the left and decoded values on the
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// right:
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//
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// 0 => 0
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// 1 => -1
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// 2 => 1
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// 3 => -2
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// 4 => 2
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// 5 => -3
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// 6 => 3
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//
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// ref: https://developers.google.com/protocol-buffers/docs/encoding
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func DecodeZigZag(x uint32) int32 {
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return int32(x>>1) ^ -int32(x&1)
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}
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// EncodeZigZag encodes a given integer to ZigZag-encoding.
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//
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// Examples of integer input on the left and corresponding ZigZag encoded values
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// on the right:
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//
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// 0 => 0
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// -1 => 1
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// 1 => 2
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// -2 => 3
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// 2 => 4
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// -3 => 5
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// 3 => 6
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//
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// ref: https://developers.google.com/protocol-buffers/docs/encoding
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func EncodeZigZag(x int32) uint32 {
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if x < 0 {
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x = -x
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return uint32(x)<<1 - 1
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}
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return uint32(x) << 1
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}
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