Inspect the Host Code - 2022.2 English

Vitis Tutorials: Hardware Acceleration (XD099)

Document ID

XD099

Release Date

2022-12-01

Version

2022.2 English

While the emulation run is executing, in another terminal, open the src/host/host.cpp file.

Inspect lines 234-236. You can see that the Filter function is called three times for the Y, U, and V channels.

request[xx*3+0] = Filter(coeff.data(), y_src.data(), width, height, stride, y_dst.data());
request[xx*3+1] = Filter(coeff.data(), u_src.data(), width, height, stride, u_dst.data());
request[xx*3+2] = Filter(coeff.data(), v_src.data(), width, height, stride, v_dst.data());

This function is described from line 78. Here, you can see kernel arguments are set, and the kernel is executed by the clEnqueueTask command.

 // Set the kernel arguments
 clSetKernelArg(mKernel, 0, sizeof(cl_mem),       &mSrcBuf[0]);
 clSetKernelArg(mKernel, 1, sizeof(cl_mem),       &mSrcBuf[1]);
 clSetKernelArg(mKernel, 2, sizeof(unsigned int), &width);
 clSetKernelArg(mKernel, 3, sizeof(unsigned int), &height);
 clSetKernelArg(mKernel, 4, sizeof(unsigned int), &stride);
 clSetKernelArg(mKernel, 5, sizeof(cl_mem),       &mDstBuf[0]);

// Schedule the writing of the inputs
clEnqueueMigrateMemObjects(mQueue, 2, mSrcBuf, 0, 0, nullptr,  &req->mEvent[0]);

// Schedule the execution of the kernel
clEnqueueTask(mQueue, mKernel, 1,  &req->mEvent[0], &req->mEvent[1]);

All three clEnqueueTask commands are enqueued using a single in-order command queue (line 73). As a result, all the commands are executed sequentially in the order they are added to the queue.

Filter2DDispatcher(
        cl_device_id     &Device,
        cl_context       &Context,
        cl_program       &Program )
  {
        mKernel  = clCreateKernel(Program, "Filter2DKernel", &mErr);
        mQueue   = clCreateCommandQueue(Context, Device, CL_QUEUE_PROFILING_ENABLE, &mErr);
        mContext = Context;
        mCounter = 0;
  }