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// Copyright 2016 The TensorFlow Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package tensorflow
// #include <string.h>
// #include "tensorflow/c/c_api.h"
import "C"
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"reflect"
"runtime"
"unsafe"
)
// DataType holds the type for a scalar value. E.g., one slot in a tensor.
type DataType C.TF_DataType
// Types of scalar values in the TensorFlow type system.
const (
Float DataType = C.TF_FLOAT
Double DataType = C.TF_DOUBLE
Int32 DataType = C.TF_INT32
Uint8 DataType = C.TF_UINT8
Int16 DataType = C.TF_INT16
Int8 DataType = C.TF_INT8
String DataType = C.TF_STRING
Complex64 DataType = C.TF_COMPLEX64
Complex DataType = C.TF_COMPLEX
Int64 DataType = C.TF_INT64
Bool DataType = C.TF_BOOL
Qint8 DataType = C.TF_QINT8
Quint8 DataType = C.TF_QUINT8
Qint32 DataType = C.TF_QINT32
Bfloat16 DataType = C.TF_BFLOAT16
Qint16 DataType = C.TF_QINT16
Quint16 DataType = C.TF_QUINT16
Uint16 DataType = C.TF_UINT16
Complex128 DataType = C.TF_COMPLEX128
Half DataType = C.TF_HALF
)
// Tensor holds a multi-dimensional array of elements of a single data type.
type Tensor struct {
c *C.TF_Tensor
shape []int64
}
// NewTensor converts from a Go value to a Tensor. Valid values are scalars,
// slices, and arrays. Every element of a slice must have the same length so
// that the resulting Tensor has a valid shape.
func NewTensor(value interface{}) (*Tensor, error) {
val := reflect.ValueOf(value)
shape, dataType, err := shapeAndDataTypeOf(val)
if err != nil {
return nil, err
}
if dataType == String {
// TODO(ashankar): Handle this
return nil, fmt.Errorf("String Tensors are not currently supported")
}
nbytes := byteSizeOf(dataType, shape)
var shapePtr *C.int64_t
if len(shape) > 0 {
shapePtr = (*C.int64_t)(unsafe.Pointer(&shape[0]))
}
t := &Tensor{
c: C.TF_AllocateTensor(C.TF_DataType(dataType), shapePtr, C.int(len(shape)), C.size_t(nbytes)),
shape: shape,
}
runtime.SetFinalizer(t, (*Tensor).finalize)
raw := tensorData(t.c)
buf := bytes.NewBuffer(raw[:0:len(raw)])
if err := encodeTensor(buf, val); err != nil {
return nil, err
}
if uintptr(buf.Len()) != nbytes {
return nil, fmt.Errorf("BUG: Please report at https://github.com/tensorflow/tensorflow/issues with the note: NewTensor incorrectly calculated the size of a tensor with type %v and shape %v as %v bytes instead of %v bytes, version %v", dataType, shape, nbytes, buf.Len(), Version())
}
return t, nil
}
// newTensorFromC takes ownership of c and returns the owning Tensor.
func newTensorFromC(c *C.TF_Tensor) *Tensor {
var shape []int64
if ndims := int(C.TF_NumDims(c)); ndims > 0 {
shape = make([]int64, ndims)
}
for i := range shape {
shape[i] = int64(C.TF_Dim(c, C.int(i)))
}
t := &Tensor{c: c, shape: shape}
runtime.SetFinalizer(t, (*Tensor).finalize)
return t
}
func (t *Tensor) finalize() { C.TF_DeleteTensor(t.c) }
// DataType returns the scalar datatype of the Tensor.
func (t *Tensor) DataType() DataType { return DataType(C.TF_TensorType(t.c)) }
// Shape returns the shape of the Tensor.
func (t *Tensor) Shape() []int64 { return t.shape }
// Value converts the Tensor to a Go value. For now, not all Tensor types are
// supported, and this function may panic if it encounters an unsupported
// DataType.
//
// The type of the output depends on the Tensor type and dimensions.
// For example:
// Tensor(int64, 0): int64
// Tensor(float64, 3): [][][]float64
func (t *Tensor) Value() interface{} {
typ, err := typeOf(t.DataType(), t.Shape())
if err != nil {
panic(err)
}
val := reflect.New(typ)
if err := decodeTensor(bytes.NewReader(tensorData(t.c)), t.Shape(), typ, val); err != nil {
panic(err)
}
return reflect.Indirect(val).Interface()
}
func tensorData(c *C.TF_Tensor) []byte {
// See: https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
cbytes := C.TF_TensorData(c)
length := int(C.TF_TensorByteSize(c))
slice := (*[1 << 30]byte)(unsafe.Pointer(cbytes))[:length:length]
return slice
}
var types = []struct {
typ reflect.Type
dataType C.TF_DataType
}{
{reflect.TypeOf(float32(0)), C.TF_FLOAT},
{reflect.TypeOf(float64(0)), C.TF_DOUBLE},
{reflect.TypeOf(int32(0)), C.TF_INT32},
{reflect.TypeOf(uint8(0)), C.TF_UINT8},
{reflect.TypeOf(int16(0)), C.TF_INT16},
{reflect.TypeOf(int8(0)), C.TF_INT8},
{reflect.TypeOf(""), C.TF_STRING},
{reflect.TypeOf(complex(float32(0), float32(0))), C.TF_COMPLEX64},
{reflect.TypeOf(int64(0)), C.TF_INT64},
{reflect.TypeOf(false), C.TF_BOOL},
{reflect.TypeOf(uint16(0)), C.TF_UINT16},
{reflect.TypeOf(complex(float64(0), float64(0))), C.TF_COMPLEX128},
// TODO(apassos): support DT_RESOURCE representation in go.
}
// shapeAndDataTypeOf returns the data type and shape of the Tensor
// corresponding to a Go type.
func shapeAndDataTypeOf(val reflect.Value) (shape []int64, dt DataType, err error) {
typ := val.Type()
for typ.Kind() == reflect.Array || typ.Kind() == reflect.Slice {
shape = append(shape, int64(val.Len()))
// If slice elements are slices, verify that all of them have the same size.
// Go's type system makes that guarantee for arrays.
if val.Len() > 0 {
if val.Type().Elem().Kind() == reflect.Slice {
expected := val.Index(0).Len()
for i := 1; i < val.Len(); i++ {
if val.Index(i).Len() != expected {
return shape, dt, fmt.Errorf("mismatched slice lengths: %d and %d", val.Index(i).Len(), expected)
}
}
}
val = val.Index(0)
}
typ = typ.Elem()
}
for _, t := range types {
if typ.Kind() == t.typ.Kind() {
return shape, DataType(t.dataType), nil
}
}
return shape, dt, fmt.Errorf("unsupported type %v", typ)
}
// typeOf converts from a DataType and Shape to the equivalent Go type.
func typeOf(dt DataType, shape []int64) (reflect.Type, error) {
var ret reflect.Type
for _, t := range types {
if dt == DataType(t.dataType) {
ret = t.typ
break
}
}
if ret == nil {
return nil, fmt.Errorf("DataType %v unsupported", dt)
}
for _ = range shape {
ret = reflect.SliceOf(ret)
}
return ret, nil
}
// byteSizeOf returns the size (in bytes) of the raw encoding of a tensor with
// the given shape and DataType. Only meant for non-String tensors.
func byteSizeOf(dt DataType, shape []int64) uintptr {
var size uintptr
for _, t := range types {
if DataType(t.dataType) == dt {
size = t.typ.Size()
break
}
}
for _, d := range shape {
size *= uintptr(d)
}
return size
}
// encodeTensor writes v to the specified buffer using the format specified in
// c_api.h.
func encodeTensor(w io.Writer, v reflect.Value) error {
switch v.Kind() {
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint8, reflect.Uint16, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
if err := binary.Write(w, nativeEndian, v.Interface()); err != nil {
return err
}
case reflect.Array, reflect.Slice:
// If slice elements are slices, verify that all of them have the same size.
// Go's type system makes that guarantee for arrays.
if v.Len() > 0 && v.Type().Elem().Kind() == reflect.Slice {
expected := v.Index(0).Len()
for i := 1; i < v.Len(); i++ {
if v.Index(i).Len() != expected {
return fmt.Errorf("mismatched slice lengths: %d and %d", v.Index(i).Len(), expected)
}
}
}
for i := 0; i < v.Len(); i++ {
err := encodeTensor(w, v.Index(i))
if err != nil {
return err
}
}
default:
return fmt.Errorf("unsupported type %v", v.Type())
}
return nil
}
// decodeTensor decodes the Tensor from the buffer to ptr using the format
// specified in c_api.h
func decodeTensor(r io.Reader, shape []int64, typ reflect.Type, ptr reflect.Value) error {
switch typ.Kind() {
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint8, reflect.Uint16, reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
if err := binary.Read(r, nativeEndian, ptr.Interface()); err != nil {
return err
}
case reflect.Slice:
val := reflect.Indirect(ptr)
val.Set(reflect.MakeSlice(typ, int(shape[0]), int(shape[0])))
for i := 0; i < val.Len(); i++ {
if err := decodeTensor(r, shape[1:], typ.Elem(), val.Index(i).Addr()); err != nil {
return err
}
}
default:
return fmt.Errorf("unsupported type %v", typ)
}
return nil
}
// nativeEndian is the byte order for the local platform. Used to send back and
// forth Tensors with the C API. We test for endianness at runtime because
// some architectures can be booted into different endian modes.
var nativeEndian binary.ByteOrder
func init() {
buf := [2]byte{}
*(*uint16)(unsafe.Pointer(&buf[0])) = uint16(0xABCD)
switch buf {
case [2]byte{0xCD, 0xAB}:
nativeEndian = binary.LittleEndian
case [2]byte{0xAB, 0xCD}:
nativeEndian = binary.BigEndian
default:
panic("Could not determine native endianness.")
}
}
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