lsst.sphgeom  21.0.0-1-g8760c09+9bc468e83a
codec.h
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1 /*
2  * LSST Data Management System
3  * Copyright 2016 AURA/LSST.
4  *
5  * This product includes software developed by the
6  * LSST Project (http://www.lsst.org/).
7  *
8  * This program is free software: you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation, either version 3 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the LSST License Statement and
19  * the GNU General Public License along with this program. If not,
20  * see <https://www.lsstcorp.org/LegalNotices/>.
21  */
22 
23 #ifndef LSST_SPHGEOM_CODEC_H_
24 #define LSST_SPHGEOM_CODEC_H_
25 
26 // Optimized path requires little endian arch and support for unaligned loads.
27 #if defined(__x86_64__) or (defined(__aarch64__) and defined(__LITTLE_ENDIAN__))
28 #define OPTIMIZED_LITTLE_ENDIAN
29 #endif
30 
31 #ifdef NO_OPTIMIZED_PATHS
32 #undef OPTIMIZED_LITTLE_ENDIAN
33 #endif
34 
38 
39 #include <vector>
40 
41 namespace lsst {
42 namespace sphgeom {
43 
46 inline void encodeDouble(double item, std::vector<uint8_t> & buffer) {
47 #ifdef OPTIMIZED_LITTLE_ENDIAN
48  auto ptr = reinterpret_cast<uint8_t const *>(&item);
49  buffer.insert(buffer.end(), ptr, ptr + 8);
50 #else
51  union { uint64_t u; double d; };
52  d = item;
53  buffer.push_back(static_cast<uint8_t>(u));
54  buffer.push_back(static_cast<uint8_t>(u >> 8));
55  buffer.push_back(static_cast<uint8_t>(u >> 16));
56  buffer.push_back(static_cast<uint8_t>(u >> 24));
57  buffer.push_back(static_cast<uint8_t>(u >> 32));
58  buffer.push_back(static_cast<uint8_t>(u >> 40));
59  buffer.push_back(static_cast<uint8_t>(u >> 48));
60  buffer.push_back(static_cast<uint8_t>(u >> 56));
61 #endif
62 }
63 
66 inline double decodeDouble(uint8_t const * buffer) {
67 #ifdef OPTIMIZED_LITTLE_ENDIAN
68  return *reinterpret_cast<double const *>(buffer);
69 #else
70  union { uint64_t u; double d; };
71  u = static_cast<uint64_t>(buffer[0]) +
72  (static_cast<uint64_t>(buffer[1]) << 8) +
73  (static_cast<uint64_t>(buffer[2]) << 16) +
74  (static_cast<uint64_t>(buffer[3]) << 24) +
75  (static_cast<uint64_t>(buffer[4]) << 32) +
76  (static_cast<uint64_t>(buffer[5]) << 40) +
77  (static_cast<uint64_t>(buffer[6]) << 48) +
78  (static_cast<uint64_t>(buffer[7]) << 56);
79  return d;
80 #endif
81 }
82 
83 }} // namespace lsst::sphgeom
84 
85 #endif // LSST_SPHGEOM_CODEC_H_
void encodeDouble(double item, std::vector< uint8_t > &buffer)
Definition: codec.h:46
double decodeDouble(uint8_t const *buffer)
Definition: codec.h:66