runtime: missed a file in alg checkin

TBR=dvyukov
CC=golang-codereviews
https://golang.org/cl/122740044

src/pkg/runtime/alg.go

@@ -0,0 +1,153 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import "unsafe"
+
+const (
+	c0 = uintptr((8-uint64(ptrSize))/4*2860486313 + (uint64(ptrSize)-4)/4*33054211828000289)
+	c1 = uintptr((8-uint64(ptrSize))/4*3267000013 + (uint64(ptrSize)-4)/4*23344194077549503)
+)
+
+const (
+	alg_MEM = iota
+	alg_MEM0
+	alg_MEM8
+	alg_MEM16
+	alg_MEM32
+	alg_MEM64
+	alg_MEM128
+	alg_NOEQ
+	alg_NOEQ0
+	alg_NOEQ8
+	alg_NOEQ16
+	alg_NOEQ32
+	alg_NOEQ64
+	alg_NOEQ128
+	alg_STRING
+	alg_INTER
+	alg_NILINTER
+	alg_SLICE
+	alg_FLOAT32
+	alg_FLOAT64
+	alg_CPLX64
+	alg_CPLX128
+	alg_max
+)
+
+var use_aeshash bool
+
+// in asm_*.s
+func aeshash(p unsafe.Pointer, s uintptr, h uintptr) uintptr
+
+func memhash(p unsafe.Pointer, s uintptr, h uintptr) uintptr {
+	if use_aeshash {
+		return aeshash(p, s, h)
+	}
+
+	h ^= c0
+	for s > 0 {
+		h = (h ^ uintptr(*(*byte)(p))) * c1
+		p = add(p, 1)
+		s--
+	}
+	return h
+}
+
+func strhash(a *string, s uintptr, h uintptr) uintptr {
+	return memhash((*stringStruct)(unsafe.Pointer(a)).str, uintptr(len(*a)), h)
+}
+
+// NOTE: Because NaN != NaN, a map can contain any
+// number of (mostly useless) entries keyed with NaNs.
+// To avoid long hash chains, we assign a random number
+// as the hash value for a NaN.
+
+func f32hash(a *float32, s uintptr, h uintptr) uintptr {
+	f := *a
+	switch {
+	case f == 0:
+		return c1 * (c0 ^ h) // +0, -0
+	case f != f:
+		return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN
+	default:
+		return c1 * (c0 ^ h ^ uintptr(*(*uint32)(unsafe.Pointer(a))))
+	}
+}
+
+func f64hash(a *float64, s uintptr, h uintptr) uintptr {
+	f := *a
+	switch {
+	case f == 0:
+		return c1 * (c0 ^ h) // +0, -0
+	case f != f:
+		return c1 * (c0 ^ h ^ uintptr(fastrand2())) // any kind of NaN
+	case ptrSize == 4:
+		x := (*[2]uintptr)(unsafe.Pointer(a))
+		return c1 * (c0 ^ h ^ (x[1] * c1) ^ x[0])
+	default:
+		return c1 * (c0 ^ h ^ *(*uintptr)(unsafe.Pointer(a)))
+	}
+}
+
+func c64hash(a *complex64, s uintptr, h uintptr) uintptr {
+	x := (*[2]float32)(unsafe.Pointer(a))
+	return f32hash(&x[1], 4, f32hash(&x[0], 4, h))
+}
+
+func c128hash(a *complex128, s uintptr, h uintptr) uintptr {
+	x := (*[2]float64)(unsafe.Pointer(a))
+	return f64hash(&x[1], 4, f64hash(&x[0], 4, h))
+}
+
+func nohash(a unsafe.Pointer, s uintptr, h uintptr) uintptr {
+	panic(errorString("hash of unhashable type"))
+}
+
+func interhash(a *interface {
+	f()
+}, s uintptr, h uintptr) uintptr {
+	return 0
+}
+
+func nilinterhash(a *interface{}, s uintptr, h uintptr) uintptr {
+	t := (*eface)(unsafe.Pointer(a))._type
+	if t == nil {
+		return h
+	}
+	fn := goalg(t.alg).hash
+	if **(**uintptr)(unsafe.Pointer(&fn)) == nohashcode {
+		// calling nohash will panic too,
+		// but we can print a better error.
+		panic(errorString("hash of unhashable type " + *t._string))
+	}
+	if uintptr(t.size) <= ptrSize {
+		return c1 * fn(unsafe.Pointer(&(*eface)(unsafe.Pointer(a)).data), uintptr(t.size), h^c0)
+	} else {
+		return c1 * fn((*eface)(unsafe.Pointer(a)).data, uintptr(t.size), h^c0)
+	}
+}
+
+// Testing adapters for hash quality tests (see hash_test.go)
+func haveGoodHash() bool {
+	return use_aeshash
+}
+
+func stringHash(s string, seed uintptr) uintptr {
+	return goalg(&algarray[alg_STRING]).hash(noescape(unsafe.Pointer(&s)), unsafe.Sizeof(s), seed)
+}
+
+func bytesHash(b []byte, seed uintptr) uintptr {
+	// TODO: use sliceStruct
+	return goalg(&algarray[alg_MEM]).hash(*(*unsafe.Pointer)(unsafe.Pointer(&b)), uintptr(len(b)), seed)
+}
+
+func int32Hash(i uint32, seed uintptr) uintptr {
+	return goalg(&algarray[alg_MEM32]).hash(noescape(unsafe.Pointer(&i)), 4, seed)
+}
+
+func int64Hash(i uint64, seed uintptr) uintptr {
+	return goalg(&algarray[alg_MEM64]).hash(noescape(unsafe.Pointer(&i)), 8, seed)
+}