Merge 783a341 into 538d003

.travis.yml

@@ -13,7 +13,9 @@ before_install:
   - go get github.com/axw/gocov/gocov
   - go get github.com/mattn/goveralls
   - go get golang.org/x/tools/cmd/cover
+  - go get github.com/klauspost/asmfmt/cmd/asmfmt
 script:
+  - test -z "$(asmfmt -l *.s)"
   - go test -v -covermode=count -coverprofile=profile.cov
 after_success:
   - goveralls -coverprofile=profile.cov -service=travis-ci

asm_x86.s

@@ -0,0 +1,56 @@
+// +build amd64,go1.6
+
+#include "textflag.h"
+
+// func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+TEXT ·cpuid(SB), NOSPLIT, $0-24
+	MOVL eaxArg+0(FP), AX
+	MOVL ecxArg+4(FP), CX
+	CPUID
+	MOVL AX, eax+8(FP)
+	MOVL BX, ebx+12(FP)
+	MOVL CX, ecx+16(FP)
+	MOVL DX, edx+20(FP)
+	RET
+
+// func EncodeInt(lat, lng float64) uint64
+TEXT ·EncodeInt(SB), NOSPLIT, $0
+	CMPB ·useAsm(SB), $1
+	JNE  fallback
+
+#define LATF	X0
+#define LATI	R8
+#define LNGF	X1
+#define LNGI	R9
+#define TEMP	R10
+#define GHSH	R11
+#define MASK	BX
+
+	MOVSD lat+0(FP), LATF
+	MOVSD lng+8(FP), LNGF
+
+	MOVQ $0x5555555555555555, MASK
+
+	MULSD $(0.005555555555555556), LATF
+	ADDSD $(1.5), LATF
+
+	MULSD $(0.002777777777777778), LNGF
+	ADDSD $(1.5), LNGF
+
+	MOVQ LNGF, LNGI
+	SHRQ $20, LNGI
+
+	MOVQ  LATF, LATI
+	SHRQ  $20, LATI
+	PDEPQ MASK, LATI, GHSH
+
+	PDEPQ MASK, LNGI, TEMP
+
+	SHLQ $1, TEMP
+	XORQ TEMP, GHSH
+
+	MOVQ GHSH, ret+16(FP)
+	RET
+
+fallback:
+	JMP ·encodeInt(SB)

benchmark_test.go

@@ -1,28 +1,19 @@
 package geohash
 
-import "testing"
+import (
+	"testing"
+)
 
-func randomPoints(n int) [][2]float64 {
-	var points [][2]float64
-	for i := 0; i < n; i++ {
-		lat, lon := RandomPoint()
-		points = append(points, [2]float64{lat, lon})
-	}
-	return points
-}
+const lat, lng = 33.0, -72.0
 
 func BenchmarkEncode(b *testing.B) {
-	points := randomPoints(b.N)
-	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		Encode(points[i][0], points[i][1])
+		_ = Encode(lat, lng)
 	}
 }
 
 func BenchmarkEncodeInt(b *testing.B) {
-	points := randomPoints(b.N)
-	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		EncodeInt(points[i][0], points[i][1])
+		_ = EncodeInt(lat, lng)
 	}
 }

geohash.go

@@ -2,7 +2,9 @@
 // geohashes.
 package geohash
 
-import "math"
+import (
+	"math"
+)
 
 // Encode the point (lat, lng) as a string geohash with the standard 12
 // characters of precision.
@@ -20,7 +22,12 @@ func EncodeWithPrecision(lat, lng float64, chars uint) string {
 }
 
 // EncodeInt encodes the point (lat, lng) to a 64-bit integer geohash.
-func EncodeInt(lat, lng float64) uint64 {
+func EncodeInt(lat, lng float64) uint64
+
+// encodeInt provides a Go implementation of integer geohash. This is the
+// default implementation of EncodeInt, but optimized versions are provided
+// for certain architectures.
+func encodeInt(lat, lng float64) uint64 {
 	latInt := encodeRange(lat, 90)
 	lngInt := encodeRange(lng, 180)
 	return interleave(latInt, lngInt)

geohash_x86.go

@@ -0,0 +1,24 @@
+// +build amd64,go1.6
+
+package geohash
+
+// useAsm flag determines whether the assembly version of EncodeInt will be
+// used. By Default we fall back to encodeInt.
+var useAsm bool
+
+// cpuid executes the CPUID instruction to obtain processor identification and
+// feature information.
+func cpuid(eaxArg, ecxArg uint32) (eax, ebx, ecx, edx uint32)
+
+// hasBMI2 returns whether the CPU supports Bit Manipulation Instruction Set
+// 2.
+func hasBMI2() bool {
+	_, ebx, _, _ := cpuid(7, 0)
+	return ebx&(1<<8) != 0
+}
+
+// init determines whether to use assembly version by performing CPU feature
+// check.
+func init() {
+	useAsm = hasBMI2()
+}

stubs.s

@@ -0,0 +1,7 @@
+// +build !amd64 !go1.6
+
+// Define NOSPLIT ourselves since "textflag.h" is missing in old Go versions.
+#define NOSPLIT	4
+
+TEXT ·EncodeInt(SB), NOSPLIT, $0
+	JMP ·encodeInt(SB)