cl image & half

src/framework/cl/cl_half.h

+/* Copyright (c) 2018 PaddlePaddle 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. */
+
+#pragma once
+#include <cstdint>
+
+typedef uint16_t half_t;
+
+half_t float2half(float f);
+float half2float(half_t h);
\ No newline at end of file

src/framework/cl/cl_image.h

@@ -17,6 +17,7 @@ limitations under the License. */
 #include "framework/ddim.h"
 #include "framework/tensor.h"
 #include "CL/cl.h"
+#include "cl_half.h"
 
 namespace paddle_mobile {
 namespace framework {
@@ -26,10 +27,56 @@ class CLImage {
   CLImage() = default;
 
   void Init(cl_context context, float *tensorInput, DDim ddim) {
+    cl_image_format cf = {
+      .image_channel_order = CL_RGBA,
+      .image_channel_data_type = CL_HALF_FLOAT
+    };
+    // NCHW -> [W * (C+3)/4, H * N]
+    size_t N = tensorDims_[0];
+    size_t C = tensorDims_[1];
+    size_t H = tensorDims_[2];
+    size_t W = tensorDims_[3];
+    size_t width = W * ((C + 3) / 4);
+    size_t height = H * N;
+    std::unique_ptr<half_t[]> imageData();
+    if (tensorInput != nullptr) {
+      imageData.reset(new half_t[width * height * 4]);
+      float *p = tensorInput;
+      size_t i0 = 0;
+      for (int n = 0; n < N; n++) {
+        for (int c = 0; c < C; c++) {
+          size_t i1 = i0;
+          for (int h = 0; h < H; h++) {
+            size_t i2 = i1 << 2 + c % 4;
+            for (int w = 0; w < W; w++) {
+              imageData[i2] = float2half(*p);
+              i2 += 4;
+              p++;
+            }
+            i1 += width;
+          }
+        }
+        i0 += width * H;
+      }
+    }
+    cl_int err;
+    cl_image_ = clCreateImage2D(
+      context, // cl_context context
+      CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, // cl_mem_flags flags
+      &cf, // const cl_image_format *image_format
+      width, // size_t image_width
+      height, // size_t image_height
+      0, // size_t image_row_pitch
+      reinterpret_cast<void*>(imageData.get()), // void *host_ptr
+      &err // cl_int *errcode_ret
+    );
+    if (err != CL_SUCCESS) {
+      // TODO: error handling
+    }
   }
 
   void Init(cl_context context, DDim ddim) {
-
+    Init(cl_context context, nullptr, DDim ddim);
   }
 
   inline CLImage &Resize(const DDim &dims) {