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util/ByteOrder: add class PackedBE64

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Max Kellermann 2022-05-17 09:26:14 +02:00 committed by Max Kellermann
parent 60a3aae35f
commit 81afb47cd0
1 changed files with 52 additions and 0 deletions
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52
src/util/ByteOrder.hxx
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@ -351,6 +351,58 @@ public:
static_assert(sizeof(PackedBE32) == sizeof(uint32_t), "Wrong size");
static_assert(alignof(PackedBE32) == 1, "Wrong alignment");
/**
* A packed big-endian 64 bit integer.
*/
class PackedBE64 {
uint8_t a, b, c, d, e, f, g, h;
public:
PackedBE64() = default;
constexpr PackedBE64(uint64_t src) noexcept
:a(uint8_t(src >> 56)),
b(uint8_t(src >> 48)),
c(uint8_t(src >> 40)),
d(uint8_t(src >> 32)),
e(uint8_t(src >> 24)),
f(uint8_t(src >> 16)),
g(uint8_t(src >> 8)),
h(uint8_t(src)) {}
/**
* Construct an instance from an integer which is already
* big-endian.
*/
static constexpr auto FromBE(uint64_t src) noexcept {
union {
uint64_t in;
PackedBE64 out;
} u{src};
return u.out;
}
constexpr operator uint64_t() const noexcept {
return (uint64_t(a) << 56) | (uint64_t(b) << 48) |
(uint64_t(c) << 40) | (uint64_t(d) << 32) |
(uint64_t(e) << 24) | (uint64_t(f) << 16) |
(uint64_t(g) << 8) | uint64_t(h);
}
/**
* Reads the raw, big-endian value.
*/
constexpr uint64_t raw() const noexcept {
uint64_t x = *this;
if (IsLittleEndian())
x = ByteSwap64(x);
return x;
}
};
static_assert(sizeof(PackedBE64) == sizeof(uint64_t), "Wrong size");
static_assert(alignof(PackedBE64) == 1, "Wrong alignment");
/**
* A packed little-endian 16 bit integer.
*/