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Commit c18af467 authored by Rob Pike's avatar Rob Pike
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encoding/binary: make Write work like Read 

Use the fast path calculation to shorten the code.
No effect on benchmarks.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/12696046
parent c32a8830
Hide whitespace changes
Inline Side-by-side
Showing with 97 additions and 101 deletions
src/pkg/encoding/binary/binary.go
View file @ c18af467
......@@ -135,7 +135,7 @@ func (bigEndian) GoString() string { return "binary.BigEndian" }
// may be used for padding.
func Read(r io.Reader, order ByteOrder, data interface{}) error {
// Fast path for basic types and slices.
if n := intReadSize(data); n != 0 {
if n := intDataSize(data); n != 0 {
var b [8]byte
var bs []byte
if n > len(b) {
......@@ -164,13 +164,11 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
case *uint64:
*data = order.Uint64(bs)
case []int8:
for i, x := range bs { // Easier to loop over the input for 8-bit cases.
for i, x := range bs { // Easier to loop over the input for 8-bit values.
data[i] = int8(x)
}
case []uint8:
for i, x := range bs { // Easier to loop over the input for 8-bit cases.
data[i] = x
}
copy(data, bs)
case []int16:
for i := range data {
data[i] = int16(order.Uint16(bs[2*i:]))
......@@ -229,97 +227,95 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
// When writing structs, zero values are written for fields
// with blank (_) field names.
func Write(w io.Writer, order ByteOrder, data interface{}) 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 []int8:
bs = make([]byte, len(v))
for i, x := range v {
bs[i] = byte(x)
}
case *uint8:
bs = b[:1]
b[0] = *v
case uint8:
bs = b[:1]
b[0] = byte(v)
case []uint8:
bs = v
case *int16:
bs = b[:2]
order.PutUint16(bs, uint16(*v))
case int16:
bs = b[:2]
order.PutUint16(bs, uint16(v))
case []int16:
bs = make([]byte, 2*len(v))
for i, x := range v {
order.PutUint16(bs[2*i:], uint16(x))
}
case *uint16:
bs = b[:2]
order.PutUint16(bs, *v)
case uint16:
bs = b[:2]
order.PutUint16(bs, v)
case []uint16:
bs = make([]byte, 2*len(v))
for i, x := range v {
order.PutUint16(bs[2*i:], x)
}
case *int32:
bs = b[:4]
order.PutUint32(bs, uint32(*v))
case int32:
bs = b[:4]
order.PutUint32(bs, uint32(v))
case []int32:
bs = make([]byte, 4*len(v))
for i, x := range v {
order.PutUint32(bs[4*i:], uint32(x))
}
case *uint32:
bs = b[:4]
order.PutUint32(bs, *v)
case uint32:
bs = b[:4]
order.PutUint32(bs, v)
case []uint32:
bs = make([]byte, 4*len(v))
for i, x := range v {
order.PutUint32(bs[4*i:], x)
}
case *int64:
bs = b[:8]
order.PutUint64(bs, uint64(*v))
case int64:
bs = b[:8]
order.PutUint64(bs, uint64(v))
case []int64:
bs = make([]byte, 8*len(v))
for i, x := range v {
order.PutUint64(bs[8*i:], uint64(x))
// Fast path for basic types and slices.
if n := intDataSize(data); n != 0 {
var b [8]byte
var bs []byte
if n > len(b) {
bs = make([]byte, n)
} else {
bs = b[:n]
}
case *uint64:
bs = b[:8]
order.PutUint64(bs, *v)
case uint64:
bs = b[:8]
order.PutUint64(bs, v)
case []uint64:
bs = make([]byte, 8*len(v))
for i, x := range v {
order.PutUint64(bs[8*i:], x)
switch v := data.(type) {
case *int8:
bs = b[:1]
b[0] = byte(*v)
case int8:
bs = b[:1]
b[0] = byte(v)
case []int8:
for i, x := range v {
bs[i] = byte(x)
}
case *uint8:
bs = b[:1]
b[0] = *v
case uint8:
bs = b[:1]
b[0] = byte(v)
case []uint8:
bs = v
case *int16:
bs = b[:2]
order.PutUint16(bs, uint16(*v))
case int16:
bs = b[:2]
order.PutUint16(bs, uint16(v))
case []int16:
for i, x := range v {
order.PutUint16(bs[2*i:], uint16(x))
}
case *uint16:
bs = b[:2]
order.PutUint16(bs, *v)
case uint16:
bs = b[:2]
order.PutUint16(bs, v)
case []uint16:
for i, x := range v {
order.PutUint16(bs[2*i:], x)
}
case *int32:
bs = b[:4]
order.PutUint32(bs, uint32(*v))
case int32:
bs = b[:4]
order.PutUint32(bs, uint32(v))
case []int32:
for i, x := range v {
order.PutUint32(bs[4*i:], uint32(x))
}
case *uint32:
bs = b[:4]
order.PutUint32(bs, *v)
case uint32:
bs = b[:4]
order.PutUint32(bs, v)
case []uint32:
for i, x := range v {
order.PutUint32(bs[4*i:], x)
}
case *int64:
bs = b[:8]
order.PutUint64(bs, uint64(*v))
case int64:
bs = b[:8]
order.PutUint64(bs, uint64(v))
case []int64:
for i, x := range v {
order.PutUint64(bs[8*i:], uint64(x))
}
case *uint64:
bs = b[:8]
order.PutUint64(bs, *v)
case uint64:
bs = b[:8]
order.PutUint64(bs, v)
case []uint64:
for i, x := range v {
order.PutUint64(bs[8*i:], x)
}
}
}
if bs != nil {
_, err := w.Write(bs)
return err
}
......@@ -609,29 +605,29 @@ func (e *encoder) skip(v reflect.Value) {
e.buf = e.buf[n:]
}
// intReadSize returns the size of the data required to represent the data when encoded.
// It returns zero if the type cannot be implemented by the fast path in Read.
func intReadSize(data interface{}) int {
// intDataSize returns the size of the data required to represent the data when encoded.
// It returns zero if the type cannot be implemented by the fast path in Read or Write.
func intDataSize(data interface{}) int {
switch data := data.(type) {
case *int8, *uint8:
case int8, *int8, *uint8:
return 1
case []int8:
return len(data)
case []uint8:
return len(data)
case *int16, *uint16:
case int16, *int16, *uint16:
return 2
case []int16:
return 2 * len(data)
case []uint16:
return 2 * len(data)
case *int32, *uint32:
case int32, *int32, *uint32:
return 4
case []int32:
return 4 * len(data)
case []uint32:
return 4 * len(data)
case *int64, *uint64:
case int64, *int64, *uint64:
return 8
case []int64:
return 8 * len(data)
......
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