GCC Code Coverage Report

Line	Branch	Decision	Exec	Source
1				/**
2				* @file scaled_channel.h
3				*/
4
5				#pragma once
6
7				#include <cmath>
8				#include <cstdint>
9				#include <type_traits>
10
11				struct scaled_channel_base { };
12
13				template <typename TTest>
14				static constexpr bool is_scaled_channel = std::is_base_of_v<scaled_channel_base, TTest>;
15
16				// This class lets us transparently store something at a ratio inside an integer type
17				// Just use it like a float - you can read and write to it, like this:
18				// scaled_channel<uint8_t, 10> myVar;
19				// myVar = 2.4f; // converts to an int, stores 24
20				// float x = myVar; // converts back to float, returns 2.4f
21				template <typename T, int mul = 1, int div = 1>
22				class scaled_channel : scaled_channel_base {
23				using TSelf = scaled_channel<T, mul, div>;
24
25				public:
26				struct IncompleteType;
27
28			54454	constexpr scaled_channel() : m_value(static_cast<T>(0)) { }
29
30				// Only allow conversion directly to T when mul/div are both 1, otherwise this constructor doesn't exist and the float conversion is used.
31			36126	constexpr scaled_channel(std::conditional_t<mul == 1 && div == 1, T, IncompleteType> val) {
32			36126	m_value = val;
33			36126	}
34
35				// Scale the float in to our scaled channel
36			54286911	constexpr scaled_channel(std::conditional_t<mul != 1 || div != 1, float, IncompleteType> val) {
37			54286911	m_value = std::roundf(val * float(mul) / div);
38			54286911	}
39
40				// Only allow conversion directly to T when mul/div are both 1, otherwise this operator doesn't exist and the float conversion is used.
41			516876	constexpr operator typename std::conditional_t<mul == 1 && div == 1, T, IncompleteType>() const {
42			516876	return m_value;
43				}
44
45				// Allow reading back out as a float (note: this may be lossy!)
46			3369164	constexpr operator typename std::conditional_t<mul != 1 || div != 1, float, IncompleteType>() const {
47			3369164	return m_value * (float(div) / mul);
48				}
49
50				// Postfix increment operator
51				// only enable if:
52				// - base type T is an integral type (integer)
53				// - multiplier is equal to 1
54				void operator++(int) {
55				static_assert(mul == 1 && div == 1,
56				"Increment operator only supported for non-scaled integer types");
57				static_assert(std::is_integral_v<T>, "Increment operator only supported for non-scaled integer types");
58
59				m_value++;
60				}
61
62			232	constexpr const char* getFirstByteAddr() const {
63			232	return &m_firstByte;
64				}
65
66				private:
67				union {
68				T m_value;
69				char m_firstByte;
70				};
71				};
72
73				// We need to guarantee that scaled values containing some type are the same size
74				// as that underlying type. We rely on the class only having a single member for
75				// this trick to work.
76				static_assert(sizeof(scaled_channel<uint8_t>) == 1);
77				static_assert(sizeof(scaled_channel<uint16_t>) == 2);
78				static_assert(sizeof(scaled_channel<uint32_t>) == 4);
79				static_assert(sizeof(scaled_channel<float>) == 4);
80
81				// make sure the scaled channel detector works
82				static_assert(!is_scaled_channel<int>);
83				static_assert(is_scaled_channel<scaled_channel<int, 5>>);
84