OpenCL enqueueNDRangeKernel causes Access Violation error - opencl

Question

I am continuously getting an Access Violation Error with a all my kernels which I am trying to build. Other kernels which I take from books seem to work fine.
https://github.com/ssarangi/VideoCL - This is where the code is.
Something seems to be missing in this. Could someone help me with this.
Thanks so much.
[James] - Thanks for the suggestion and you are right. I am doing it on Win 7 with a AMD Redwood card. I have the Catalyst 11.7 drivers with AMD APP SDK 2.5. I am posting the code below.
#include <iostream>
#include "bmpfuncs.h"
#include "CLManager.h"
void main()
{
float theta = 3.14159f/6.0f;
int W ;
int H ;
const char* inputFile = "input.bmp";
const char* outputFile = "output.bmp";
float* ip = readImage(inputFile, &W, &H);
float *op = new float[W*H];
//We assume that the input image is the array “ip”
//and the angle of rotation is theta
float cos_theta = cos(theta);
float sin_theta = sin(theta);
try
{
CLManager* clMgr = new CLManager();
// Build the Source
unsigned int pgmID = clMgr->buildSource("rotation.cl");
// Create the kernel
cl::Kernel* kernel = clMgr->makeKernel(pgmID, "img_rotate");
// Create the memory Buffers
cl::Buffer* clIp = clMgr->createBuffer(CL_MEM_READ_ONLY, W*H*sizeof(float));
cl::Buffer* clOp = clMgr->createBuffer(CL_MEM_READ_WRITE, W*H*sizeof(float));
// Get the command Queue
cl::CommandQueue* queue = clMgr->getCmdQueue();
queue->enqueueWriteBuffer(*clIp, CL_TRUE, 0, W*H*sizeof(float), ip);
// Set the arguments to the kernel
kernel->setArg(0, clOp);
kernel->setArg(1, clIp);
kernel->setArg(2, W);
kernel->setArg(3, H);
kernel->setArg(4, sin_theta);
kernel->setArg(5, cos_theta);
// Run the kernel on specific NDRange
cl::NDRange globalws(W, H);
queue->enqueueNDRangeKernel(*kernel, cl::NullRange, globalws, cl::NullRange);
queue->enqueueReadBuffer(*clOp, CL_TRUE, 0, W*H*sizeof(float), op);
storeImage(op, outputFile, H, W, inputFile);
}
catch(cl::Error error)
{
std::cout << error.what() << "(" << error.err() << ")" << std::endl;
}
}
I am getting the error at the queue->enqueueNDRangeKernel line.
I have the queue and the kernel stored in a class.
CLManager::CLManager()
: m_programIDs(-1)
{
// Initialize the Platform
cl::Platform::get(&m_platforms);
// Create a Context
cl_context_properties cps[3] = {
CL_CONTEXT_PLATFORM,
(cl_context_properties)(m_platforms[0])(),
0
};
m_context = cl::Context(CL_DEVICE_TYPE_GPU, cps);
// Get a list of devices on this platform
m_devices = m_context.getInfo<CL_CONTEXT_DEVICES>();
cl_int err;
m_queue = new cl::CommandQueue(m_context, m_devices[0], 0, &err);
}
cl::Kernel* CLManager::makeKernel(unsigned int programID, std::string kernelName)
{
cl::CommandQueue queue = cl::CommandQueue(m_context, m_devices[0]);
cl::Kernel* kernel = new cl::Kernel(*(m_programs[programID]), kernelName.c_str());
m_kernels.push_back(kernel);
return kernel;
}

Answer 1

I checked your code. I'm on Linux though. At runtime I'm getting Error -38, which means CL_INVALID_MEM_OBJECT. So I went and checked your buffers.
cl::Buffer* clIp = clMgr->createBuffer(CL_MEM_READ_ONLY, W*H*sizeof(float));
cl::Buffer* clOp = clMgr->createBuffer(CL_MEM_READ_WRITE, W*H*sizeof(float));
Then you pass the buffers as a Pointer:
kernel->setArg(0, clOp);
kernel->setArg(1, clIp);
But setArg is expecting a value, so the buffer pointers should be dereferenced:
kernel->setArg(0, *clOp);
kernel->setArg(1, *clIp);
After those changes the cat rotates ;)