add cast from uint8 to float, test=develop (#2080)

* add cast from uint8 to float, test=develop

lite/kernels/arm/cast_compute.cc

@@ -53,6 +53,12 @@ void CastCompute::Run() {
     // float>);
     // todo: the input type actually is float.
     memcpy(out_data, x_data_begin, sizeof(float) * param.X->numel());
+  } else if (param.in_dtype == 20 && param.out_dtype == 5) {  // uint8->float32
+    const unsigned char* x_data_begin = param.X->data<unsigned char>();
+    const unsigned char* x_data_end = x_data_begin + param.X->numel();
+    float* out_data = param.Out->mutable_data<float>();
+    std::transform(
+        x_data_begin, x_data_end, out_data, TransOp<unsigned char, float>);
   } else {
     LOG(FATAL) << "other has not been implemented";
   }

lite/tests/kernels/cast_compute_test.cc

@@ -27,7 +27,7 @@ class CastComputeTester : public arena::TestCase {
   std::string output_ = "out";
   int in_dtype_;
   int out_dtype_;
-  DDim x_dims_{{2, 2, 2, 2}};
+  DDim x_dims_{{2, 2}};
 
  public:
   CastComputeTester(const Place& place,
@@ -41,27 +41,32 @@ class CastComputeTester : public arena::TestCase {
     CHECK(out);
     out->Resize(x_dims_);
 
-    if (out_dtype_ == 5 && in_dtype_ == 21) {
+    if (out_dtype_ == 5 && in_dtype_ == 20) {
+      auto* x = scope->FindTensor(input_);
+      auto* x_data = x->data<unsigned char>();
+      auto* output_data = out->mutable_data<float>();
+      for (int i = 0; i < x_dims_.production(); i++) {
+        *output_data = static_cast<float>(*x_data);
+        output_data++;
+        x_data++;
+      }
+    } else if (out_dtype_ == 5 && in_dtype_ == 21) {
       auto* output_data = out->mutable_data<float>();
       auto* x = scope->FindTensor(input_);
       auto* x_data = x->data<char>();
-      auto* output_data_tmp = output_data;
-      auto* x_data_tmp = x_data;
       for (int i = 0; i < x_dims_.production(); i++) {
-        *output_data_tmp = static_cast<float>(*x_data_tmp);
-        output_data_tmp++;
-        x_data_tmp++;
+        *output_data = static_cast<float>(*x_data);
+        output_data++;
+        x_data++;
       }
     } else if (out_dtype_ == 5 && in_dtype_ == 2) {
       auto* output_data = out->mutable_data<float>();
       auto* x = scope->FindTensor(input_);
       auto* x_data = x->data<int32_t>();
-      auto* output_data_tmp = output_data;
-      auto* x_data_tmp = x_data;
       for (int i = 0; i < x_dims_.production(); i++) {
-        *output_data_tmp = static_cast<float>(*x_data_tmp);
-        output_data_tmp++;
-        x_data_tmp++;
+        *output_data = static_cast<float>(*x_data);
+        output_data++;
+        x_data++;
       }
     }
   }
@@ -75,7 +80,13 @@ class CastComputeTester : public arena::TestCase {
   }
 
   void PrepareData() override {
-    if (in_dtype_ == 21) {
+    if (in_dtype_ == 20) {
+      std::vector<unsigned char> x_data(x_dims_.production());
+      for (int i = 0; i < x_dims_.production(); i++) {
+        x_data[i] = static_cast<unsigned char>(i % 128);
+      }
+      SetCommonTensor(input_, x_dims_, x_data.data());
+    } else if (in_dtype_ == 21) {
       std::vector<char> x_data(x_dims_.production());
       for (int i = 0; i < x_dims_.production(); i++) {
         float sign = i % 3 == 0 ? -1.0f : 1.0f;
@@ -101,7 +112,7 @@ TEST(Cast, precision) {
   Place place(TARGET(kARM));
 
   std::unique_ptr<arena::TestCase> tester(
-      new CastComputeTester(place, "def", 21, 5));
+      new CastComputeTester(place, "def", 20, 5));
   arena::Arena arena(std::move(tester), place, 2e-5);
   arena.TestPrecision();