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Date: Mon, 8 Jul 2013 00:36:14 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: String pass to GPU and get back
Just looking at your code I think you miss an enqueueReadBuffer() of bufferA before running the kernel.
magnum
On 7 Jul, 2013, at 22:08 , marcus.desto <marcus.desto@...pl> wrote:
> Hi,
>
> I have troubles with setting up a program to use some of your opencl implementations.
> Therefore I try to understand how to pass a string to the GPU and get it back to the host program to print it.
> I did it with a uint array without problems. But using uchar for passing a string I stuck.
>
> OpenCL:
> __kernel void same_in_same_out_char(__global uchar * out, __constant uchar * in){
> for (unsigned int ui=0; ui<3; ui++) out[ui]=in[ui];
> }
>
> C++
> #define __CL_ENABLE_EXCEPTIONS
>
> #include <fstream>
> #include <iostream>
> #include <iterator>
> #include <CL/cl.hpp>
> #include <CL/opencl.h>
>
>
> using namespace std;
> int main () {
>
> vector<cl::Platform> platforms;
> vector<cl::Device> devices;
> vector<cl::Kernel> kernels;
>
> try {
>
> // create platform
> cl::Platform::get(&platforms);
> platforms[0].getDevices(CL_DEVICE_TYPE_GPU, &devices);
>
> // create context
> cl::Context context(devices);
>
> // create command queue
> cl::CommandQueue queue(context, devices[0]);
>
> // load opencl source
> ifstream cl_file("inout.cl");
> string cl_string(istreambuf_iterator<char>(cl_file), (istreambuf_iterator<char>()));
> cl::Program::Sources source(1, make_pair(cl_string.c_str(),
> cl_string.length() + 1));
>
> // create program
> cl::Program program(context, source);
>
> // compile opencl source
> program.build(devices);
>
> // load named kernel from opencl source
> cl::Kernel kernel(program, "same_in_same_out_char");
>
> // create a message to send to kernel ----------------------------------------------------------------
> const char pwd[] = "MAX";
> cout << "char pwd[] : " << pwd << endl;
> cl_uchar * password = (cl_uchar*) &pwd;
> int bufferA_size = 3; // array size is 3
>
> int bufferC_size = 3; // array size is 3
> cout << " -- OpenCL -- " << endl;
> // ---------------------------------------------------------------------------------------------------
> // allocate device buffer to hold message
> cl::Buffer bufferA(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(cl_uchar) * bufferA_size, password);
> cl::Buffer bufferC(context, CL_MEM_WRITE_ONLY, sizeof(cl_uchar) * bufferC_size);
>
> // set message as kernel argument
> kernel.setArg(0, bufferC);
> kernel.setArg(1, bufferA);
>
> // execute kernel
> queue.enqueueTask(kernel);
>
> // wait for completion
> queue.finish();
> // ----------------------
>
> cl_uint out_global[bufferC_size];
> queue.enqueueReadBuffer(bufferC, CL_TRUE, 0, bufferC_size*sizeof(cl_uchar), &out_global);
>
> cout << "Output \t\t:" << *out_global << endl << "Output[1..n] \t:";
> for (unsigned int i=0; i<bufferC_size; i ++) cout << out_global[i] << " " ;
>
> cout << endl;
> } catch (cl::Error e) {
> cout << endl << e.what() << " : " << e.err() << endl;
> }
>
> return 0;
>
> }
>
> Any ideas?
>
> (Thanks)
> Regards
> Marcus
>
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