Merge pull request #7 from fxamacker/fxamacker/add-hash64uint64x2

Add Hash64Uint64x2 and rename HashString64

Author: fxamacker

circlehash64.go

@@ -14,12 +14,24 @@
 
 package circlehash
 
+import (
+	"unsafe"
+)
+
 // Hash64 returns a 64-bit digest of data.
+// Digest is compatible with CircleHash64f.
 func Hash64(b []byte, seed uint64) uint64 {
-	return uint64(circle64f(*(*ptr)(ptr(&b)), seed, uint64(len(b))))
+	return uint64(circle64f(*(*unsafe.Pointer)(unsafe.Pointer(&b)), seed, uint64(len(b))))
+}
+
+// Hash64String returns a 64-bit digest of s.
+// Digest is compatible with Hash64.
+func Hash64String(s string, seed uint64) uint64 {
+	return uint64(circle64f(*(*unsafe.Pointer)(unsafe.Pointer(&s)), seed, uint64(len(s))))
 }
 
-// HashString64 returns a 64-bit digest of string s.
-func HashString64(s string, seed uint64) uint64 {
-	return uint64(circle64f(*(*ptr)(ptr(&s)), seed, uint64(len(s))))
+// Hash64Uint64x2 returns a 64-bit digest of a and b.
+// Digest is compatible with Hash64 with byte slice of len 16.
+func Hash64Uint64x2(a uint64, b uint64, seed uint64) uint64 {
+	return circle64fUint64x2(a, b, seed)
 }

circlehash64_test.go

@@ -302,9 +302,18 @@ func nonUniformBytes16KiB() []byte {
 // countedCircleHash64 calls Hash64 and increments countCircleHash64.
 func countedCircleHash64(t *testing.T, data []byte, seed uint64) uint64 {
 	digest := Hash64(data, seed)
-	digest2 := HashString64(string(data), seed)
+	digest2 := Hash64String(string(data), seed)
 	if digest != digest2 {
-		t.Errorf("Hash64() 0x%x != HashString64() 0x%x", digest, digest2)
+		t.Errorf("Hash64() 0x%x != Hash64String() 0x%x", digest, digest2)
+	}
+
+	if len(data) == 16 {
+		a := binary.LittleEndian.Uint64(data)
+		b := binary.LittleEndian.Uint64(data[8:])
+		digest3 := Hash64Uint64x2(a, b, seed)
+		if digest != digest3 {
+			t.Errorf("Hash64() 0x%x != Hash64Uint64x2() 0x%x", digest, digest3)
+		}
 	}
 
 	collisions[digest]++

circlehash64f.go

@@ -96,3 +96,13 @@ func circle64f(p unsafe.Pointer, seed uint64, dlen uint64) uint64 {
 	z := pi4 ^ startingLength // wyhash reuses salt1 here, but CircleHash64 (like Go 1.17) avoids reusing it here
 	return mix64(w, z)
 }
+
+// circle64fUint64x2 produces a 64-bit digest from a, b, and seed.
+// Digest is compatible with circlehash64f with byte slice of len 16.
+func circle64fUint64x2(a uint64, b uint64, seed uint64) uint64 {
+	const dataLen = uint64(16)
+	currentState := seed ^ pi0
+	w := mix64(a^pi1, b^currentState)
+	z := pi4 ^ dataLen
+	return mix64(w, z)
+}

utils.go

@@ -19,10 +19,6 @@ import (
 	"unsafe"
 )
 
-type (
-	ptr = unsafe.Pointer
-)
-
 func add(p unsafe.Pointer, x uintptr) unsafe.Pointer {
 	return unsafe.Pointer(uintptr(p) + x)
 }