Imported Upstream version 60upstream/60

3 files changed, 744 insertions, 0 deletions

diff --git a/src/pkg/encoding/binary/Makefile b/src/pkg/encoding/binary/Makefile
new file mode 100644
index 000000000..dc46abe90
--- /dev/null
+++ b/src/pkg/encoding/binary/Makefile
@@ -0,0 +1,11 @@
+# Copyright 2009 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.
+
+include ../../../Make.inc
+
+TARG=encoding/binary
+GOFILES=\
+	binary.go\
+
+include ../../../Make.pkg
diff --git a/src/pkg/encoding/binary/binary.go b/src/pkg/encoding/binary/binary.go
new file mode 100644
index 000000000..8e55cb23b
--- /dev/null
+++ b/src/pkg/encoding/binary/binary.go
@@ -0,0 +1,498 @@
+// Copyright 2009 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 binary implements translation between
+// unsigned integer values and byte sequences
+// and the reading and writing of fixed-size values.
+package binary
+
+import (
+	"math"
+	"io"
+	"os"
+	"reflect"
+)
+
+// A ByteOrder specifies how to convert byte sequences into
+// 16-, 32-, or 64-bit unsigned integers.
+type ByteOrder interface {
+	Uint16(b []byte) uint16
+	Uint32(b []byte) uint32
+	Uint64(b []byte) uint64
+	PutUint16([]byte, uint16)
+	PutUint32([]byte, uint32)
+	PutUint64([]byte, uint64)
+	String() string
+}
+
+// This is byte instead of struct{} so that it can be compared,
+// allowing, e.g., order == binary.LittleEndian.
+type unused byte
+
+// LittleEndian is the little-endian implementation of ByteOrder.
+var LittleEndian littleEndian
+
+// BigEndian is the big-endian implementation of ByteOrder.
+var BigEndian bigEndian
+
+type littleEndian unused
+
+func (littleEndian) Uint16(b []byte) uint16 { return uint16(b[0]) | uint16(b[1])<<8 }
+
+func (littleEndian) PutUint16(b []byte, v uint16) {
+	b[0] = byte(v)
+	b[1] = byte(v >> 8)
+}
+
+func (littleEndian) Uint32(b []byte) uint32 {
+	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+}
+
+func (littleEndian) PutUint32(b []byte, v uint32) {
+	b[0] = byte(v)
+	b[1] = byte(v >> 8)
+	b[2] = byte(v >> 16)
+	b[3] = byte(v >> 24)
+}
+
+func (littleEndian) Uint64(b []byte) uint64 {
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
+		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
+}
+
+func (littleEndian) PutUint64(b []byte, v uint64) {
+	b[0] = byte(v)
+	b[1] = byte(v >> 8)
+	b[2] = byte(v >> 16)
+	b[3] = byte(v >> 24)
+	b[4] = byte(v >> 32)
+	b[5] = byte(v >> 40)
+	b[6] = byte(v >> 48)
+	b[7] = byte(v >> 56)
+}
+
+func (littleEndian) String() string { return "LittleEndian" }
+
+func (littleEndian) GoString() string { return "binary.LittleEndian" }
+
+type bigEndian unused
+
+func (bigEndian) Uint16(b []byte) uint16 { return uint16(b[1]) | uint16(b[0])<<8 }
+
+func (bigEndian) PutUint16(b []byte, v uint16) {
+	b[0] = byte(v >> 8)
+	b[1] = byte(v)
+}
+
+func (bigEndian) Uint32(b []byte) uint32 {
+	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+}
+
+func (bigEndian) PutUint32(b []byte, v uint32) {
+	b[0] = byte(v >> 24)
+	b[1] = byte(v >> 16)
+	b[2] = byte(v >> 8)
+	b[3] = byte(v)
+}
+
+func (bigEndian) Uint64(b []byte) uint64 {
+	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+}
+
+func (bigEndian) PutUint64(b []byte, v uint64) {
+	b[0] = byte(v >> 56)
+	b[1] = byte(v >> 48)
+	b[2] = byte(v >> 40)
+	b[3] = byte(v >> 32)
+	b[4] = byte(v >> 24)
+	b[5] = byte(v >> 16)
+	b[6] = byte(v >> 8)
+	b[7] = byte(v)
+}
+
+func (bigEndian) String() string { return "BigEndian" }
+
+func (bigEndian) GoString() string { return "binary.BigEndian" }
+
+// Read reads structured binary data from r into data.
+// Data must be a pointer to a fixed-size value or a slice
+// of fixed-size values.
+// A fixed-size value is either a fixed-size arithmetic
+// type (int8, uint8, int16, float32, complex64, ...)
+// or an array or struct containing only fixed-size values.
+// Bytes read from r are decoded using the specified byte order
+// and written to successive fields of the data.
+func Read(r io.Reader, order ByteOrder, data interface{}) os.Error {
+	// Fast path for basic types.
+	if n := intDestSize(data); n != 0 {
+		var b [8]byte
+		bs := b[:n]
+		if _, err := io.ReadFull(r, bs); err != nil {
+			return err
+		}
+		switch v := data.(type) {
+		case *int8:
+			*v = int8(b[0])
+		case *uint8:
+			*v = b[0]
+		case *int16:
+			*v = int16(order.Uint16(bs))
+		case *uint16:
+			*v = order.Uint16(bs)
+		case *int32:
+			*v = int32(order.Uint32(bs))
+		case *uint32:
+			*v = order.Uint32(bs)
+		case *int64:
+			*v = int64(order.Uint64(bs))
+		case *uint64:
+			*v = order.Uint64(bs)
+		}
+		return nil
+	}
+
+	// Fallback to reflect-based.
+	var v reflect.Value
+	switch d := reflect.ValueOf(data); d.Kind() {
+	case reflect.Ptr:
+		v = d.Elem()
+	case reflect.Slice:
+		v = d
+	default:
+		return os.NewError("binary.Read: invalid type " + d.Type().String())
+	}
+	size := TotalSize(v)
+	if size < 0 {
+		return os.NewError("binary.Read: invalid type " + v.Type().String())
+	}
+	d := &decoder{order: order, buf: make([]byte, size)}
+	if _, err := io.ReadFull(r, d.buf); err != nil {
+		return err
+	}
+	d.value(v)
+	return nil
+}
+
+// Write writes the binary representation of data into w.
+// Data must be a fixed-size value or a pointer to
+// a fixed-size value.
+// A fixed-size value is either a fixed-size arithmetic
+// type (int8, uint8, int16, float32, complex64, ...)
+// or an array or struct containing only fixed-size values.
+// Bytes written to w are encoded using the specified byte order
+// and read from successive fields of the data.
+func Write(w io.Writer, order ByteOrder, data interface{}) os.Error {
+	// Fast path for basic types.
+	var b [8]byte
+	var bs []byte
+	switch v := data.(type) {
+	case *int8:
+		bs = b[:1]
+		b[0] = byte(*v)
+	case int8:
+		bs = b[:1]
+		b[0] = byte(v)
+	case *uint8:
+		bs = b[:1]
+		b[0] = *v
+	case uint8:
+		bs = b[:1]
+		b[0] = byte(v)
+	case *int16:
+		bs = b[:2]
+		order.PutUint16(bs, uint16(*v))
+	case int16:
+		bs = b[:2]
+		order.PutUint16(bs, uint16(v))
+	case *uint16:
+		bs = b[:2]
+		order.PutUint16(bs, *v)
+	case uint16:
+		bs = b[:2]
+		order.PutUint16(bs, v)
+	case *int32:
+		bs = b[:4]
+		order.PutUint32(bs, uint32(*v))
+	case int32:
+		bs = b[:4]
+		order.PutUint32(bs, uint32(v))
+	case *uint32:
+		bs = b[:4]
+		order.PutUint32(bs, *v)
+	case uint32:
+		bs = b[:4]
+		order.PutUint32(bs, v)
+	case *int64:
+		bs = b[:8]
+		order.PutUint64(bs, uint64(*v))
+	case int64:
+		bs = b[:8]
+		order.PutUint64(bs, uint64(v))
+	case *uint64:
+		bs = b[:8]
+		order.PutUint64(bs, *v)
+	case uint64:
+		bs = b[:8]
+		order.PutUint64(bs, v)
+	}
+	if bs != nil {
+		_, err := w.Write(bs)
+		return err
+	}
+	v := reflect.Indirect(reflect.ValueOf(data))
+	size := TotalSize(v)
+	if size < 0 {
+		return os.NewError("binary.Write: invalid type " + v.Type().String())
+	}
+	buf := make([]byte, size)
+	e := &encoder{order: order, buf: buf}
+	e.value(v)
+	_, err := w.Write(buf)
+	return err
+}
+
+func TotalSize(v reflect.Value) int {
+	if v.Kind() == reflect.Slice {
+		elem := sizeof(v.Type().Elem())
+		if elem < 0 {
+			return -1
+		}
+		return v.Len() * elem
+	}
+	return sizeof(v.Type())
+}
+
+func sizeof(t reflect.Type) int {
+	switch t.Kind() {
+	case reflect.Array:
+		n := sizeof(t.Elem())
+		if n < 0 {
+			return -1
+		}
+		return t.Len() * n
+
+	case reflect.Struct:
+		sum := 0
+		for i, n := 0, t.NumField(); i < n; i++ {
+			s := sizeof(t.Field(i).Type)
+			if s < 0 {
+				return -1
+			}
+			sum += s
+		}
+		return sum
+
+	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+		reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
+		return int(t.Size())
+	}
+	return -1
+}
+
+type decoder struct {
+	order ByteOrder
+	buf   []byte
+}
+
+type encoder struct {
+	order ByteOrder
+	buf   []byte
+}
+
+func (d *decoder) uint8() uint8 {
+	x := d.buf[0]
+	d.buf = d.buf[1:]
+	return x
+}
+
+func (e *encoder) uint8(x uint8) {
+	e.buf[0] = x
+	e.buf = e.buf[1:]
+}
+
+func (d *decoder) uint16() uint16 {
+	x := d.order.Uint16(d.buf[0:2])
+	d.buf = d.buf[2:]
+	return x
+}
+
+func (e *encoder) uint16(x uint16) {
+	e.order.PutUint16(e.buf[0:2], x)
+	e.buf = e.buf[2:]
+}
+
+func (d *decoder) uint32() uint32 {
+	x := d.order.Uint32(d.buf[0:4])
+	d.buf = d.buf[4:]
+	return x
+}
+
+func (e *encoder) uint32(x uint32) {
+	e.order.PutUint32(e.buf[0:4], x)
+	e.buf = e.buf[4:]
+}
+
+func (d *decoder) uint64() uint64 {
+	x := d.order.Uint64(d.buf[0:8])
+	d.buf = d.buf[8:]
+	return x
+}
+
+func (e *encoder) uint64(x uint64) {
+	e.order.PutUint64(e.buf[0:8], x)
+	e.buf = e.buf[8:]
+}
+
+func (d *decoder) int8() int8 { return int8(d.uint8()) }
+
+func (e *encoder) int8(x int8) { e.uint8(uint8(x)) }
+
+func (d *decoder) int16() int16 { return int16(d.uint16()) }
+
+func (e *encoder) int16(x int16) { e.uint16(uint16(x)) }
+
+func (d *decoder) int32() int32 { return int32(d.uint32()) }
+
+func (e *encoder) int32(x int32) { e.uint32(uint32(x)) }
+
+func (d *decoder) int64() int64 { return int64(d.uint64()) }
+
+func (e *encoder) int64(x int64) { e.uint64(uint64(x)) }
+
+func (d *decoder) value(v reflect.Value) {
+	switch v.Kind() {
+	case reflect.Array:
+		l := v.Len()
+		for i := 0; i < l; i++ {
+			d.value(v.Index(i))
+		}
+	case reflect.Struct:
+		l := v.NumField()
+		for i := 0; i < l; i++ {
+			d.value(v.Field(i))
+		}
+
+	case reflect.Slice:
+		l := v.Len()
+		for i := 0; i < l; i++ {
+			d.value(v.Index(i))
+		}
+
+	case reflect.Int8:
+		v.SetInt(int64(d.int8()))
+	case reflect.Int16:
+		v.SetInt(int64(d.int16()))
+	case reflect.Int32:
+		v.SetInt(int64(d.int32()))
+	case reflect.Int64:
+		v.SetInt(d.int64())
+
+	case reflect.Uint8:
+		v.SetUint(uint64(d.uint8()))
+	case reflect.Uint16:
+		v.SetUint(uint64(d.uint16()))
+	case reflect.Uint32:
+		v.SetUint(uint64(d.uint32()))
+	case reflect.Uint64:
+		v.SetUint(d.uint64())
+
+	case reflect.Float32:
+		v.SetFloat(float64(math.Float32frombits(d.uint32())))
+	case reflect.Float64:
+		v.SetFloat(math.Float64frombits(d.uint64()))
+
+	case reflect.Complex64:
+		v.SetComplex(complex(
+			float64(math.Float32frombits(d.uint32())),
+			float64(math.Float32frombits(d.uint32())),
+		))
+	case reflect.Complex128:
+		v.SetComplex(complex(
+			math.Float64frombits(d.uint64()),
+			math.Float64frombits(d.uint64()),
+		))
+	}
+}
+
+func (e *encoder) value(v reflect.Value) {
+	switch v.Kind() {
+	case reflect.Array:
+		l := v.Len()
+		for i := 0; i < l; i++ {
+			e.value(v.Index(i))
+		}
+	case reflect.Struct:
+		l := v.NumField()
+		for i := 0; i < l; i++ {
+			e.value(v.Field(i))
+		}
+	case reflect.Slice:
+		l := v.Len()
+		for i := 0; i < l; i++ {
+			e.value(v.Index(i))
+		}
+
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		switch v.Type().Kind() {
+		case reflect.Int8:
+			e.int8(int8(v.Int()))
+		case reflect.Int16:
+			e.int16(int16(v.Int()))
+		case reflect.Int32:
+			e.int32(int32(v.Int()))
+		case reflect.Int64:
+			e.int64(v.Int())
+		}
+
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
+		switch v.Type().Kind() {
+		case reflect.Uint8:
+			e.uint8(uint8(v.Uint()))
+		case reflect.Uint16:
+			e.uint16(uint16(v.Uint()))
+		case reflect.Uint32:
+			e.uint32(uint32(v.Uint()))
+		case reflect.Uint64:
+			e.uint64(v.Uint())
+		}
+
+	case reflect.Float32, reflect.Float64:
+		switch v.Type().Kind() {
+		case reflect.Float32:
+			e.uint32(math.Float32bits(float32(v.Float())))
+		case reflect.Float64:
+			e.uint64(math.Float64bits(v.Float()))
+		}
+
+	case reflect.Complex64, reflect.Complex128:
+		switch v.Type().Kind() {
+		case reflect.Complex64:
+			x := v.Complex()
+			e.uint32(math.Float32bits(float32(real(x))))
+			e.uint32(math.Float32bits(float32(imag(x))))
+		case reflect.Complex128:
+			x := v.Complex()
+			e.uint64(math.Float64bits(real(x)))
+			e.uint64(math.Float64bits(imag(x)))
+		}
+	}
+}
+
+// intDestSize returns the size of the integer that ptrType points to,
+// or 0 if the type is not supported.
+func intDestSize(ptrType interface{}) int {
+	switch ptrType.(type) {
+	case *int8, *uint8:
+		return 1
+	case *int16, *uint16:
+		return 2
+	case *int32, *uint32:
+		return 4
+	case *int64, *uint64:
+		return 8
+	}
+	return 0
+}
diff --git a/src/pkg/encoding/binary/binary_test.go b/src/pkg/encoding/binary/binary_test.go
new file mode 100644
index 000000000..b266996f6
--- /dev/null
+++ b/src/pkg/encoding/binary/binary_test.go
@@ -0,0 +1,235 @@
+// Copyright 2009 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 binary
+
+import (
+	"io"
+	"os"
+	"bytes"
+	"math"
+	"reflect"
+	"testing"
+)
+
+type Struct struct {
+	Int8       int8
+	Int16      int16
+	Int32      int32
+	Int64      int64
+	Uint8      uint8
+	Uint16     uint16
+	Uint32     uint32
+	Uint64     uint64
+	Float32    float32
+	Float64    float64
+	Complex64  complex64
+	Complex128 complex128
+	Array      [4]uint8
+}
+
+type T struct {
+	Int     int
+	Uint    uint
+	Uintptr uintptr
+	Array   [4]int
+}
+
+var s = Struct{
+	0x01,
+	0x0203,
+	0x04050607,
+	0x08090a0b0c0d0e0f,
+	0x10,
+	0x1112,
+	0x13141516,
+	0x1718191a1b1c1d1e,
+
+	math.Float32frombits(0x1f202122),
+	math.Float64frombits(0x232425262728292a),
+	complex(
+		math.Float32frombits(0x2b2c2d2e),
+		math.Float32frombits(0x2f303132),
+	),
+	complex(
+		math.Float64frombits(0x333435363738393a),
+		math.Float64frombits(0x3b3c3d3e3f404142),
+	),
+
+	[4]uint8{0x43, 0x44, 0x45, 0x46},
+}
+
+var big = []byte{
+	1,
+	2, 3,
+	4, 5, 6, 7,
+	8, 9, 10, 11, 12, 13, 14, 15,
+	16,
+	17, 18,
+	19, 20, 21, 22,
+	23, 24, 25, 26, 27, 28, 29, 30,
+
+	31, 32, 33, 34,
+	35, 36, 37, 38, 39, 40, 41, 42,
+	43, 44, 45, 46, 47, 48, 49, 50,
+	51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66,
+
+	67, 68, 69, 70,
+}
+
+var little = []byte{
+	1,
+	3, 2,
+	7, 6, 5, 4,
+	15, 14, 13, 12, 11, 10, 9, 8,
+	16,
+	18, 17,
+	22, 21, 20, 19,
+	30, 29, 28, 27, 26, 25, 24, 23,
+
+	34, 33, 32, 31,
+	42, 41, 40, 39, 38, 37, 36, 35,
+	46, 45, 44, 43, 50, 49, 48, 47,
+	58, 57, 56, 55, 54, 53, 52, 51, 66, 65, 64, 63, 62, 61, 60, 59,
+
+	67, 68, 69, 70,
+}
+
+var src = []byte{1, 2, 3, 4, 5, 6, 7, 8}
+var res = []int32{0x01020304, 0x05060708}
+
+func checkResult(t *testing.T, dir string, order, err os.Error, have, want interface{}) {
+	if err != nil {
+		t.Errorf("%v %v: %v", dir, order, err)
+		return
+	}
+	if !reflect.DeepEqual(have, want) {
+		t.Errorf("%v %v:\n\thave %+v\n\twant %+v", dir, order, have, want)
+	}
+}
+
+func testRead(t *testing.T, order ByteOrder, b []byte, s1 interface{}) {
+	var s2 Struct
+	err := Read(bytes.NewBuffer(b), order, &s2)
+	checkResult(t, "Read", order, err, s2, s1)
+}
+
+func testWrite(t *testing.T, order ByteOrder, b []byte, s1 interface{}) {
+	buf := new(bytes.Buffer)
+	err := Write(buf, order, s1)
+	checkResult(t, "Write", order, err, buf.Bytes(), b)
+}
+
+func TestBigEndianRead(t *testing.T) { testRead(t, BigEndian, big, s) }
+
+func TestLittleEndianRead(t *testing.T) { testRead(t, LittleEndian, little, s) }
+
+func TestBigEndianWrite(t *testing.T) { testWrite(t, BigEndian, big, s) }
+
+func TestLittleEndianWrite(t *testing.T) { testWrite(t, LittleEndian, little, s) }
+
+func TestBigEndianPtrWrite(t *testing.T) { testWrite(t, BigEndian, big, &s) }
+
+func TestLittleEndianPtrWrite(t *testing.T) { testWrite(t, LittleEndian, little, &s) }
+
+func TestReadSlice(t *testing.T) {
+	slice := make([]int32, 2)
+	err := Read(bytes.NewBuffer(src), BigEndian, slice)
+	checkResult(t, "ReadSlice", BigEndian, err, slice, res)
+}
+
+func TestWriteSlice(t *testing.T) {
+	buf := new(bytes.Buffer)
+	err := Write(buf, BigEndian, res)
+	checkResult(t, "WriteSlice", BigEndian, err, buf.Bytes(), src)
+}
+
+func TestWriteT(t *testing.T) {
+	buf := new(bytes.Buffer)
+	ts := T{}
+	err := Write(buf, BigEndian, ts)
+	if err == nil {
+		t.Errorf("WriteT: have nil, want non-nil")
+	}
+
+	tv := reflect.Indirect(reflect.ValueOf(ts))
+	for i, n := 0, tv.NumField(); i < n; i++ {
+		err = Write(buf, BigEndian, tv.Field(i).Interface())
+		if err == nil {
+			t.Errorf("WriteT.%v: have nil, want non-nil", tv.Field(i).Type())
+		}
+	}
+}
+
+type byteSliceReader struct {
+	remain []byte
+}
+
+func (br *byteSliceReader) Read(p []byte) (int, os.Error) {
+	n := copy(p, br.remain)
+	br.remain = br.remain[n:]
+	return n, nil
+}
+
+func BenchmarkRead(b *testing.B) {
+	var ls Struct
+	bsr := &byteSliceReader{}
+	var r io.Reader = bsr
+
+	for i := 0; i < b.N; i++ {
+		bsr.remain = big
+		Read(r, BigEndian, &ls.Int8)
+		Read(r, BigEndian, &ls.Int16)
+		Read(r, BigEndian, &ls.Int32)
+		Read(r, BigEndian, &ls.Int64)
+		Read(r, BigEndian, &ls.Uint8)
+		Read(r, BigEndian, &ls.Uint16)
+		Read(r, BigEndian, &ls.Uint32)
+		Read(r, BigEndian, &ls.Uint64)
+	}
+
+	want := s
+	want.Float32 = 0
+	want.Float64 = 0
+	want.Complex64 = 0
+	want.Complex128 = 0
+	for i := range want.Array {
+		want.Array[i] = 0
+	}
+	if !reflect.DeepEqual(ls, want) {
+		panic("no match")
+	}
+}
+
+func BenchmarkWrite(b *testing.B) {
+	buf := new(bytes.Buffer)
+	var w io.Writer = buf
+
+	for i := 0; i < b.N; i++ {
+		buf.Reset()
+		Write(w, BigEndian, &s.Int8)
+		Write(w, BigEndian, &s.Int16)
+		Write(w, BigEndian, &s.Int32)
+		Write(w, BigEndian, &s.Int64)
+		Write(w, BigEndian, &s.Uint8)
+		Write(w, BigEndian, &s.Uint16)
+		Write(w, BigEndian, &s.Uint32)
+		Write(w, BigEndian, &s.Uint64)
+		Write(w, BigEndian, s.Int8)
+		Write(w, BigEndian, s.Int16)
+		Write(w, BigEndian, s.Int32)
+		Write(w, BigEndian, s.Int64)
+		Write(w, BigEndian, s.Uint8)
+		Write(w, BigEndian, s.Uint16)
+		Write(w, BigEndian, s.Uint32)
+		Write(w, BigEndian, s.Uint64)
+	}
+
+	if !bytes.Equal(buf.Bytes()[:30], big[:30]) {
+		panic("first half doesn't match")
+	}
+	if !bytes.Equal(buf.Bytes()[30:], big[:30]) {
+		panic("second half doesn't match")
+	}
+}