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util/ByteOrder: add classes PackedBE16, PackedLE16, PackedLE32

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This commit is contained in:
Max Kellermann 2021-02-16 17:37:00 +01:00
parent f679961564
commit 75c8d2235b
1 changed files with 147 additions and 1 deletions
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148
src/util/ByteOrder.hxx
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@ -1,5 +1,5 @@
/*
* Copyright (C) 2011-2015 Max Kellermann <max.kellermann@gmail.com>,
* Copyright 2011-2021 Max Kellermann <max.kellermann@gmail.com>,
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@ -254,4 +254,150 @@ FromLE16S(uint16_t value) noexcept
return static_cast<int16_t>(FromLE16(value));
}
/**
* A packed big-endian 16 bit integer.
*/
class PackedBE16 {
uint8_t hi, lo;
public:
PackedBE16() = default;
constexpr PackedBE16(uint16_t src) noexcept
:hi(uint8_t(src >> 8)),
lo(uint8_t(src)) {}
/**
* Construct an instance from an integer which is already
* big-endian.
*/
static constexpr auto FromBE(uint16_t src) noexcept {
union {
uint16_t in;
PackedBE16 out;
} u{src};
return u.out;
}
constexpr operator uint16_t() const noexcept {
return (uint16_t(hi) << 8) | uint16_t(lo);
}
/**
* Reads the raw, big-endian value.
*/
constexpr uint16_t raw() const noexcept {
uint16_t x = *this;
if (IsLittleEndian())
x = ByteSwap16(x);
return x;
}
};
static_assert(sizeof(PackedBE16) == sizeof(uint16_t), "Wrong size");
static_assert(alignof(PackedBE16) == 1, "Wrong alignment");
/**
* A packed little-endian 16 bit integer.
*/
class PackedLE16 {
uint8_t lo, hi;
public:
PackedLE16() = default;
constexpr PackedLE16(uint16_t src) noexcept
:lo(uint8_t(src)),
hi(uint8_t(src >> 8)) {}
/**
* Construct an instance from an integer which is already
* little-endian.
*/
static constexpr auto FromLE(uint16_t src) noexcept {
union {
uint16_t in;
PackedLE16 out;
} u{src};
return u.out;
}
constexpr operator uint16_t() const noexcept {
return (uint16_t(hi) << 8) | uint16_t(lo);
}
PackedLE16 &operator=(uint16_t new_value) noexcept {
lo = uint8_t(new_value);
hi = uint8_t(new_value >> 8);
return *this;
}
/**
* Reads the raw, little-endian value.
*/
constexpr uint16_t raw() const noexcept {
uint16_t x = *this;
if (IsBigEndian())
x = ByteSwap16(x);
return x;
}
};
static_assert(sizeof(PackedLE16) == sizeof(uint16_t), "Wrong size");
static_assert(alignof(PackedLE16) == 1, "Wrong alignment");
/**
* A packed little-endian 32 bit integer.
*/
class PackedLE32 {
uint8_t a, b, c, d;
public:
PackedLE32() = default;
constexpr PackedLE32(uint32_t src) noexcept
:a(uint8_t(src)),
b(uint8_t(src >> 8)),
c(uint8_t(src >> 16)),
d(uint8_t(src >> 24)) {}
/**
* Construct an instance from an integer which is already
* little-endian.
*/
static constexpr auto FromLE(uint32_t src) noexcept {
union {
uint32_t in;
PackedLE32 out;
} u{src};
return u.out;
}
constexpr operator uint32_t() const noexcept {
return uint32_t(a) | (uint32_t(b) << 8) |
(uint32_t(c) << 16) | (uint32_t(d) << 24);
}
PackedLE32 &operator=(uint32_t new_value) noexcept {
a = uint8_t(new_value);
b = uint8_t(new_value >> 8);
c = uint8_t(new_value >> 16);
d = uint8_t(new_value >> 24);
return *this;
}
/**
* Reads the raw, little-endian value.
*/
constexpr uint32_t raw() const noexcept {
uint32_t x = *this;
if (IsBigEndian())
x = ByteSwap32(x);
return x;
}
};
static_assert(sizeof(PackedLE32) == sizeof(uint32_t), "Wrong size");
static_assert(alignof(PackedLE32) == 1, "Wrong alignment");
#endif