42 lines
990 B
Markdown
42 lines
990 B
Markdown
# geohash
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Integer [geohash](https://en.wikipedia.org/wiki/Geohash) encoding.
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Refer to ["Geohash in Golang Assembly"](https://mmcloughlin.com/posts/geohash-assembly) for implementation details.
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[embedmd]:# (asm.go /func main/ $)
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```go
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func main() {
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TEXT("EncodeInt", "func(lat, lng float64) uint64")
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Doc("EncodeInt computes the 64-bit integer geohash of (lat, lng).")
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lat := Load(Param("lat"), Xv())
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lng := Load(Param("lng"), Xv())
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MULSD(ConstData("reciprocal180", F64(1/180.0)), lat)
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onepointfive := ConstData("onepointfive", F64(1.5))
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ADDSD(onepointfive, lat)
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MULSD(ConstData("reciprocal360", F64(1/360.0)), lng)
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ADDSD(onepointfive, lng)
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lngi, lati := GP64v(), GP64v()
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MOVQ(lat, lati)
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SHRQ(U8(20), lati)
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MOVQ(lng, lngi)
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SHRQ(U8(20), lngi)
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mask := ConstData("mask", U64(0x5555555555555555))
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ghsh := GP64v()
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PDEPQ(mask, lati, ghsh)
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temp := GP64v()
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PDEPQ(mask, lngi, temp)
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SHLQ(U8(1), temp)
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XORQ(temp, ghsh)
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Store(ghsh, ReturnIndex(0))
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RET()
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Generate()
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}
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```
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