1 // Copyright 2020 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 #pragma once 15 16 #include <cstdint> 17 18 namespace pw::i2c { 19 20 // The Address is a helper class which represents I2C addresses which is 21 // used by pw::i2c APIs. 22 // 23 // Example usage: 24 // constexpr Address foo = Address::SevenBit<0x42>(); 25 // uint8_t foo_raw_address = foo.GetSevenBit(); 26 // 27 // const Address bar(0x200); // 10 bit address. 28 // uint16_t bar_raw_address = bar.GetTenBit(); 29 // // Note that bar.GetSevenBit() would assert here. 30 // 31 class Address { 32 public: 33 static constexpr uint8_t kMaxSevenBitAddress = (1 << 7) - 1; 34 static constexpr uint16_t kMaxTenBitAddress = (1 << 10) - 1; 35 36 // Helper constructor to ensure the address fits in the address space at 37 // compile time, skipping the construction time assert. 38 template <uint16_t kAddress> TenBit()39 static constexpr Address TenBit() { 40 static_assert(kAddress <= kMaxTenBitAddress); 41 return Address(kAddress, kAlreadyCheckedAddress); 42 } 43 44 // Helper constructor to ensure the address fits in the address space at 45 // compile time, skipping the construction time assert. 46 template <uint8_t kAddress> SevenBit()47 static constexpr Address SevenBit() { 48 static_assert(kAddress <= kMaxSevenBitAddress); 49 return Address(kAddress, kAlreadyCheckedAddress); 50 } 51 52 // Precondition: The address is at least a valid ten bit address. 53 explicit Address(uint16_t address); 54 55 // Precondition: The address is a valid 7 bit address. 56 uint8_t GetSevenBit() const; 57 GetTenBit()58 uint16_t GetTenBit() const { return address_; } 59 60 private: 61 enum AlreadyCheckedAddress { kAlreadyCheckedAddress }; Address(uint16_t address,AlreadyCheckedAddress)62 constexpr Address(uint16_t address, AlreadyCheckedAddress) 63 : address_(address) {} 64 65 uint16_t address_; 66 }; 67 68 } // namespace pw::i2c 69