code/avo

Files

Michael McLoughlin 9c70781236 all: go 1.17 (#197 )

Bump CI Go versions to 1.16 and 1.17.
Update build tags with `go:build` equivalents.
Upgrade asmfmt tool for new `go:build` support.

Updates #183

2021-10-29 01:18:34 -07:00

asm.go

all: go 1.17 (#197 )

2021-10-29 01:18:34 -07:00

doc.go

doc: add package-level doc comments (#9 )

2019-01-05 17:23:56 -08:00

geohash_test.go

examples: cpu feature checks (#171 )

2021-04-06 22:24:58 -07:00

geohash.s

pass,printer: display required ISA features (#120 )

2020-01-19 16:45:09 -08:00

README.md

doc: forgot to regenerate on last commit

2019-01-06 20:16:26 -08:00

stub.go

examples: add most docstrings

2018-12-27 23:09:44 -08:00

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()
}