How to pass vector parameter to OpenCL kernel in C?

Question

I'm having trouble passing a vector type (uint8) parameter to an OpenCL kernel function from the host code in C. In the host I've got the data in an array: ``` cl_uint dataArr[8] = { 1, 2, 3, 4, 5, 6, 7, 8 }; ``` (My real data is more than just [1, 8]; this is just for ease of explanation.) I then transfer the data over to a buffer to be passed to the kernel: ``` cl_mem kernelInputData = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(cl_uint)*8, dataArr, NULL); ``` Next, I pass this buffer into the kernel: ``` clSetKernelArg(kernel, 0, sizeof(cl_mem), &kernelInputData); ``` And the kernel function's signature looks something like this: ``` kernel void kernelFunction(constant uint8 *vectorPtr) ``` However, the kernel doesn't seem to be obtaining the correct input data from the pointer to `kernelInputData`. When I pass values back from within the kernel, I see that `vectorPtr` points to something with this structure: `( 1, 2, 3, 4, 5, ?, ?, ? )` where the questi…

Accepted Answer

You are defining an array of cl_uint of size 8. The creation of the cl_mem and the setting of kernel argument are right. But your kernel argument isn't correct: you try to read an array of cl_uint8 instead of cl_uint.

If you want to use a vector data type, you must declare: cl_uint8 dataArr of size 1. Or if you want to use an array of size 8: `kernel void kernelFunction(constant uint *vectorPtr, uint size):`

Edit:

The kernel parameter for `cl_uint8 dataVector` is not a pointer. So, the correct code is:

```
cl_uint8 dataVector = { 1, 2, 3, 4, 5, 6, 7, 8 };
clSetKernelArg(kernel, 0, sizeof(cl_uint8), &dataVector);
```

and

```
kernel void kernelFunction(constant uint8 vectorPtr)
```

How to pass vector parameter to OpenCL kernel in C?

Solution

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