55 lines
1.4 KiB
Plaintext
55 lines
1.4 KiB
Plaintext
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#include <thrust/copy.h>
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#include <thrust/device_vector.h>
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#include <thrust/reduce.h>
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#include <cuda/iterator>
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#include <iostream>
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#include <iterator>
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// This example computes a run-length code [1] for an array of characters.
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//
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// [1] http://en.wikipedia.org/wiki/Run-length_encoding
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int main()
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{
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// input data on the host
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const char data[] = "aaabbbbbcddeeeeeeeeeff";
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const size_t N = (sizeof(data) / sizeof(char)) - 1;
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// copy input data to the device
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thrust::device_vector<char> input(data, data + N);
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// allocate storage for output data and run lengths
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thrust::device_vector<char> output(N);
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thrust::device_vector<int> lengths(N);
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// print the initial data
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std::cout << "input data:" << '\n';
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thrust::copy(input.begin(), input.end(), std::ostream_iterator<char>(std::cout, ""));
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std::cout << '\n' << '\n';
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// compute run lengths
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size_t num_runs =
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thrust::reduce_by_key(
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input.begin(),
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input.end(), // input key sequence
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cuda::constant_iterator<int>(1), // input value sequence
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output.begin(), // output key sequence
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lengths.begin() // output value sequence
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)
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.first
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- output.begin(); // compute the output size
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// print the output
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std::cout << "run-length encoded output:" << '\n';
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for (size_t i = 0; i < num_runs; i++)
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{
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std::cout << "(" << output[i] << "," << lengths[i] << ")";
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}
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std::cout << '\n';
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return 0;
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}
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