Files
mpd/src/util/HexFormat.hxx
2022-03-14 12:18:52 +01:00

116 lines
3.4 KiB
C++

/*
* Copyright 2007-2022 CM4all GmbH
* All rights reserved.
*
* author: Max Kellermann <mk@cm4all.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "ConstBuffer.hxx"
#include "StringBuffer.hxx"
#include <cstddef>
#include <cstdint>
constexpr char hex_digits[] = "0123456789abcdef";
[[gnu::always_inline]]
static constexpr char *
HexFormatUint8Fixed(char dest[2], uint8_t number) noexcept
{
dest[0] = hex_digits[(number >> 4) & 0xf];
dest[1] = hex_digits[number & 0xf];
return dest + 2;
}
[[gnu::always_inline]]
static constexpr char *
HexFormatUint16Fixed(char dest[4], uint16_t number) noexcept
{
dest[0] = hex_digits[(number >> 12) & 0xf];
dest[1] = hex_digits[(number >> 8) & 0xf];
dest[2] = hex_digits[(number >> 4) & 0xf];
dest[3] = hex_digits[number & 0xf];
return dest + 4;
}
[[gnu::always_inline]]
static constexpr char *
HexFormatUint32Fixed(char dest[8], uint32_t number) noexcept
{
dest[0] = hex_digits[(number >> 28) & 0xf];
dest[1] = hex_digits[(number >> 24) & 0xf];
dest[2] = hex_digits[(number >> 20) & 0xf];
dest[3] = hex_digits[(number >> 16) & 0xf];
dest[4] = hex_digits[(number >> 12) & 0xf];
dest[5] = hex_digits[(number >> 8) & 0xf];
dest[6] = hex_digits[(number >> 4) & 0xf];
dest[7] = hex_digits[number & 0xf];
return dest + 8;
}
[[gnu::always_inline]]
static constexpr char *
HexFormatUint64Fixed(char dest[16], uint64_t number) noexcept
{
dest = HexFormatUint32Fixed(dest, number >> 32);
dest = HexFormatUint32Fixed(dest, number);
return dest;
}
/**
* Format the given input buffer of bytes to hex. The caller ensures
* that the output buffer is at least twice as large as the input.
* Does not null-terminate the output buffer.
*
* @return a pointer to one after the last written character
*/
constexpr char *
HexFormat(char *output, ConstBuffer<uint8_t> input) noexcept
{
for (const auto &i : input)
output = HexFormatUint8Fixed(output, i);
return output;
}
/**
* Like HexFormat(), but return a #StringBuffer with exactly the
* required size.
*/
template<size_t size>
[[gnu::pure]]
constexpr auto
HexFormatBuffer(const uint8_t *src) noexcept
{
StringBuffer<size * 2 + 1> dest;
*HexFormat(dest.data(), {src, size}) = 0;
return dest;
}