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
}
// 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)
dims, dataType, err := dimsAndDataTypeOf(val.Type())
if err != nil {
return nil, err
}
// TODO(ashankar): Remove the bytes.Buffer and endcode directly into
// C-memory, avoiding the memcpy and cutting down memory usage in half.
shape := make([]int64, dims)
buf := new(bytes.Buffer)
if err := encodeTensor(buf, shape, val); err != nil {
return nil, err
}
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(buf.Len())),
shape: shape,
}
runtime.SetFinalizer(t, (*Tensor).finalize)
if buf.Len() > 0 {
slice := buf.Bytes() // https://github.com/golang/go/issues/14210
C.memcpy(C.TF_TensorData(t.c), unsafe.Pointer(&slice[0]), C.size_t(buf.Len()))
}
return t, nil
}
// c converts the Tensor to a *C.TF_Tensor. Callers must take ownership of
// the *C.TF_Tensor, either by passing ownership to the C API or explicitly
// calling C.TF_DeleteTensor() on it.
func (t *Tensor) c() *C.TF_Tensor {
var shapePtr *C.int64_t
if len(t.shape) > 0 {
shapePtr = (*C.int64_t)(unsafe.Pointer(&t.shape[0]))
}
tensor := C.TF_AllocateTensor(C.TF_DataType(t.dt), shapePtr, C.int(len(t.shape)), C.size_t(t.buf.Len()))
if t.buf.Len() > 0 {
slice := t.buf.Bytes() // https://github.com/golang/go/issues/14210
C.memcpy(C.TF_TensorData(tensor), unsafe.Pointer(&slice[0]), C.size_t(t.buf.Len()))
}
return tensor
}
// newTensorFromC converts from a C.TF_Tensor to a Tensor.
func newTensorFromC(ct *C.TF_Tensor) *Tensor {
t := &Tensor{dt: DataType(C.TF_TensorType(ct))}
numDims := int(C.TF_NumDims(ct))
for i := 0; i < numDims; i++ {
t.shape = append(t.shape, int64(C.TF_Dim(ct, C.int(i))))
}
b := make([]byte, int(C.TF_TensorByteSize(ct)))
if len(b) > 0 {
C.memcpy(unsafe.Pointer(&b[0]), C.TF_TensorData(ct), C.size_t(len(b)))
}
t.buf = bytes.NewBuffer(b)
return t
}
// 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)
// See: https://github.com/golang/go/wiki/cgo#turning-c-arrays-into-go-slices
cbytes := C.TF_TensorData(t.c)
length := int(C.TF_TensorByteSize(t.c))
slice := (*[1 << 30]byte)(unsafe.Pointer(cbytes))[:length:length]
if err := decodeTensor(bytes.NewReader(slice), t.Shape(), typ, val); err != nil {
panic(err)
}
return reflect.Indirect(val).Interface()
}
