1 /*
2  * Copyright 2018 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #pragma once
18 
19 #include <iterator>
20 #include <memory>
21 
22 namespace bluetooth {
23 
24 // Forward declare Packet class
25 class Packet;
26 
27 // std::iterator is deprecated in C++17 onwards. Instead, you must declare all
28 // 5 aliases that the iterator needs for the std library.
29 #if __cplusplus >= 201703L
30 struct IteratorTraits {
31   using iterator_category = std::random_access_iterator_tag;
32   using value_type = uint8_t;
33   using difference_type = std::ptrdiff_t;
34   using pointer = uint8_t*;
35   using reference = uint8_t&;
36 };
37 #else
38 struct IteratorTraits : public std::iterator<std::random_access_iterator_tag, uint8_t> {};
39 #endif
40 
41 // Iterator is a custom iterator class for Packets.
42 class Iterator : public IteratorTraits {
43 public:
44   Iterator(std::shared_ptr<const Packet> packet, size_t i);
45   Iterator(const Iterator& itr);
46 
47   // All addition and subtraction operators are bounded from 0 to the length of
48   // the packet.
49   Iterator operator+(size_t offset);
50   Iterator& operator+=(size_t offset);
51   Iterator operator++(int);
52   Iterator& operator++();
53 
54   Iterator operator-(size_t offset);
55   int operator-(const Iterator& itr);
56   Iterator& operator-=(size_t offset);
57   Iterator operator--(int);
58   Iterator& operator--();
59 
60   Iterator& operator=(const Iterator& itr);
61 
62   bool operator!=(const Iterator& itr) const;
63   bool operator==(const Iterator& itr) const;
64 
65   bool operator<(const Iterator& itr) const;
66   bool operator>(const Iterator& itr) const;
67 
68   bool operator<=(const Iterator& itr) const;
69   bool operator>=(const Iterator& itr) const;
70 
71   uint8_t operator*() const;
72 
73   template <typename FixedWidthIntegerType>
extract()74   FixedWidthIntegerType extract() {
75     static_assert(std::is_integral<FixedWidthIntegerType>::value,
76                   "Iterator::extract requires an integral type.");
77 
78     FixedWidthIntegerType extracted_value = 0;
79     for (size_t i = 0; i < sizeof(FixedWidthIntegerType); i++) {
80       extracted_value |= static_cast<FixedWidthIntegerType>(**this) << i * 8;
81       (*this)++;
82     }
83 
84     return extracted_value;
85   }
86 
87   // Extract in Little Endian Format
88   template <typename FixedWidthIntegerType>
extractBE()89   FixedWidthIntegerType extractBE() {
90     static_assert(std::is_integral<FixedWidthIntegerType>::value,
91                   "Iterator::extract requires an integral type.");
92 
93     FixedWidthIntegerType extracted_value = 0;
94     for (size_t i = 0; i < sizeof(FixedWidthIntegerType); i++) {
95       extracted_value |= static_cast<FixedWidthIntegerType>(**this)
96                          << (sizeof(FixedWidthIntegerType) - 1 - i) * 8;
97       (*this)++;
98     }
99 
100     return extracted_value;
101   }
102 
extract8()103   uint8_t extract8() { return extract<uint8_t>(); }
extract16()104   uint16_t extract16() { return extract<uint16_t>(); }
extract32()105   uint32_t extract32() { return extract<uint32_t>(); }
extract64()106   uint64_t extract64() { return extract<uint64_t>(); }
107 
108 private:
109   std::shared_ptr<const Packet> packet_;
110   size_t index_;
111 };  // Iterator
112 
113 }  // namespace bluetooth
114