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      1 /* Copyright 2017 The TensorFlow Authors. All Rights Reserved.
      2 
      3 Licensed under the Apache License, Version 2.0 (the "License");
      4 you may not use this file except in compliance with the License.
      5 You may obtain a copy of the License at
      6 
      7     http://www.apache.org/licenses/LICENSE-2.0
      8 
      9 Unless required by applicable law or agreed to in writing, software
     10 distributed under the License is distributed on an "AS IS" BASIS,
     11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 See the License for the specific language governing permissions and
     13 limitations under the License.
     14 ==============================================================================*/
     15 
     16 #include "tensorflow/lite/string_util.h"
     17 
     18 #include <stdlib.h>
     19 #include <string.h>
     20 #include <vector>
     21 #include "tensorflow/lite/c/c_api_internal.h"
     22 
     23 namespace tflite {
     24 namespace {
     25 
     26 // Convenient method to get pointer to int32_t.
     27 const int32_t* GetIntPtr(const char* ptr) {
     28   return reinterpret_cast<const int32_t*>(ptr);
     29 }
     30 
     31 }  // namespace
     32 
     33 void DynamicBuffer::AddString(const char* str, size_t len) {
     34   data_.resize(data_.size() + len);
     35   memcpy(data_.data() + offset_.back(), str, len);
     36   offset_.push_back(offset_.back() + len);
     37 }
     38 
     39 void DynamicBuffer::AddString(const StringRef& string) {
     40   AddString(string.str, string.len);
     41 }
     42 
     43 void DynamicBuffer::AddJoinedString(const std::vector<StringRef>& strings,
     44                                     char separator) {
     45   // Resize the data buffer.
     46   int total_len = strings.size() - 1;
     47   for (StringRef ref : strings) {
     48     total_len += ref.len;
     49   }
     50   data_.resize(data_.size() + total_len);
     51 
     52   int current_idx = 0;
     53   for (StringRef ref : strings) {
     54     char* dst = data_.data() + offset_.back() + current_idx;
     55 
     56     // Fill separator if not first string.
     57     if (current_idx != 0) {
     58       *dst = separator;
     59       ++dst;
     60       ++current_idx;
     61     }
     62 
     63     // Fill content of the string.
     64     memcpy(dst, ref.str, ref.len);
     65     current_idx += ref.len;
     66   }
     67   offset_.push_back(offset_.back() + total_len);
     68 }
     69 
     70 int DynamicBuffer::WriteToBuffer(char** buffer) {
     71   // Allocate sufficient memory to tensor buffer.
     72   int32_t num_strings = offset_.size() - 1;
     73   // Total bytes include:
     74   //   * size of content (data_.size)
     75   //   * offset of each tensor (sizeof(int32_t) * num_strings)
     76   //   * length of whole buffer (int32_t)
     77   //   * num of strings (int32_t).
     78   int32_t bytes = data_.size()                            // size of content
     79                   + sizeof(int32_t) * (num_strings + 2);  // size of header
     80 
     81   // Caller will take ownership of buffer.
     82   *buffer = reinterpret_cast<char*>(malloc(bytes));
     83 
     84   // Set num of string
     85   memcpy(*buffer, &num_strings, sizeof(int32_t));
     86 
     87   // Set offset of strings.
     88   int32_t start = sizeof(int32_t) * (num_strings + 2);
     89   for (int i = 0; i < offset_.size(); i++) {
     90     int32_t offset = start + offset_[i];
     91     memcpy(*buffer + sizeof(int32_t) * (i + 1), &offset, sizeof(int32_t));
     92   }
     93 
     94   // Copy data of strings.
     95   memcpy(*buffer + start, data_.data(), data_.size());
     96   return bytes;
     97 }
     98 
     99 void DynamicBuffer::WriteToTensorAsVector(TfLiteTensor* tensor) {
    100   auto dims = TfLiteIntArrayCreate(1);
    101   dims->data[0] = offset_.size() - 1;  // Store number of strings.
    102   WriteToTensor(tensor, dims);
    103 }
    104 
    105 void DynamicBuffer::WriteToTensor(TfLiteTensor* tensor,
    106                                   TfLiteIntArray* new_shape) {
    107   char* tensor_buffer;
    108   int bytes = WriteToBuffer(&tensor_buffer);
    109 
    110   if (new_shape == nullptr) {
    111     new_shape = TfLiteIntArrayCopy(tensor->dims);
    112   }
    113 
    114   // Set tensor content pointer to tensor_buffer, and release original data.
    115   TfLiteTensorReset(tensor->type, tensor->name, new_shape, tensor->params,
    116                     tensor_buffer, bytes, kTfLiteDynamic, tensor->allocation,
    117                     tensor->is_variable, tensor);
    118 }
    119 
    120 int GetStringCount(const char* raw_buffer) {
    121   // The first integers in the raw buffer is the number of strings.
    122   return *GetIntPtr(raw_buffer);
    123 }
    124 
    125 int GetStringCount(const TfLiteTensor* tensor) {
    126   // The first integers in the raw buffer is the number of strings.
    127   return GetStringCount(tensor->data.raw);
    128 }
    129 
    130 StringRef GetString(const char* raw_buffer, int string_index) {
    131   const int32_t* offset =
    132       GetIntPtr(raw_buffer + sizeof(int32_t) * (string_index + 1));
    133   return {
    134       raw_buffer + (*offset),
    135       (*(offset + 1)) - (*offset),
    136   };
    137 }
    138 
    139 StringRef GetString(const TfLiteTensor* tensor, int string_index) {
    140   return GetString(tensor->data.raw, string_index);
    141 }
    142 
    143 }  // namespace tflite
    144