85 lines
1.8 KiB
C++
85 lines
1.8 KiB
C++
#include "util/hilbert_value.hpp"
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namespace osrm
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{
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namespace util
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{
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namespace
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{
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std::uint64_t bitInterleaving(const std::uint32_t longitude, const std::uint32_t latitude)
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{
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std::uint64_t result = 0;
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for (std::int8_t index = 31; index >= 0; --index)
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{
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result |= (latitude >> index) & 1;
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result <<= 1;
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result |= (longitude >> index) & 1;
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if (0 != index)
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{
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result <<= 1;
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}
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}
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return result;
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}
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void transposeCoordinate(std::uint32_t *x)
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{
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std::uint32_t M = 1u << (32 - 1), P, Q, t;
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int i;
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// Inverse undo
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for (Q = M; Q > 1; Q >>= 1)
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{
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P = Q - 1;
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for (i = 0; i < 2; ++i)
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{
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const bool condition = (x[i] & Q);
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if (condition)
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{
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x[0] ^= P; // invert
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}
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else
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{
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t = (x[0] ^ x[i]) & P;
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x[0] ^= t;
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x[i] ^= t;
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}
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} // exchange
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}
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// Gray encode
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for (i = 1; i < 2; ++i)
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{
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x[i] ^= x[i - 1];
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}
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t = 0;
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for (Q = M; Q > 1; Q >>= 1)
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{
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const bool condition = (x[2 - 1] & Q);
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if (condition)
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{
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t ^= Q - 1;
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}
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} // check if this for loop is wrong
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for (i = 0; i < 2; ++i)
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{
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x[i] ^= t;
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}
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}
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} // anonymous ns
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std::uint64_t hilbertCode(const Coordinate coordinate)
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{
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std::uint32_t location[2];
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location[0] = static_cast<std::int32_t>(coordinate.lon) +
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static_cast<std::int32_t>(180 * COORDINATE_PRECISION);
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location[1] = static_cast<std::int32_t>(coordinate.lat) +
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static_cast<std::int32_t>(90 * COORDINATE_PRECISION);
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transposeCoordinate(location);
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return bitInterleaving(location[0], location[1]);
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}
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}
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}
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