Find file History
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Type Name Latest commit message Commit time
..
Failed to load latest commit information.
README.md
asm.go
doc.go
geohash.s
geohash_test.go
stub.go

README.md

geohash

Integer geohash encoding.

Refer to "Geohash in Golang Assembly" for implementation details.

func main() {
	TEXT("EncodeInt", NOSPLIT, "func(lat, lng float64) uint64")
	Doc("EncodeInt computes the 64-bit integer geohash of (lat, lng).")
	lat := Load(Param("lat"), XMM())
	lng := Load(Param("lng"), XMM())

	MULSD(ConstData("reciprocal180", F64(1/180.0)), lat)
	onepointfive := ConstData("onepointfive", F64(1.5))
	ADDSD(onepointfive, lat)

	MULSD(ConstData("reciprocal360", F64(1/360.0)), lng)
	ADDSD(onepointfive, lng)

	lngi, lati := GP64(), GP64()
	MOVQ(lat, lati)
	SHRQ(U8(20), lati)
	MOVQ(lng, lngi)
	SHRQ(U8(20), lngi)

	mask := ConstData("mask", U64(0x5555555555555555))
	ghsh := GP64()
	PDEPQ(mask, lati, ghsh)
	temp := GP64()
	PDEPQ(mask, lngi, temp)
	SHLQ(U8(1), temp)
	XORQ(temp, ghsh)

	Store(ghsh, ReturnIndex(0))
	RET()

	Generate()
}