libcruft-util/endian.cpp

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2011-08-29 14:36:03 +10:00
/*
* This file is part of libgim.
*
* libgim is free software: you can redistribute it and/or modify it under the
* terms of the GNU General Public License as published by the Free Software
* Foundation, either version 3 of the License, or (at your option) any later
* version.
*
* libgim is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
2012-04-23 13:06:41 +10:00
* Copyright 2010 Danny Robson <danny@nerdcruft.net>
2011-08-29 14:36:03 +10:00
*/
#include "endian.hpp"
#include <cstdio>
#include <type_traits>
using std::is_fundamental;
using std::is_unsigned;
#ifdef WORDS_BIGENDIAN
/* Big endian doesn't need swapping */
template <typename T>
T hton (T val) {
static_assert (is_fundamental <T>(), "hton implementation assumes fundamental types");
static_assert (is_unsigned <T>(), "hton implementation does not handle signed");
return val;
}
template <typename T>
T ntoh (T val) {
static_assert (is_fundamental <T>(), "ntoh implementation assumes fundamental types");
static_assert (is_unsigned <T>(), "ntoh implementation does not handle signed");
return val;
}
template <> uint8_t hton ( uint8_t);
template <> uint16_t hton (uint16_t);
template <> uint32_t hton (uint32_t);
template <> uint64_t hton (uint64_t);
template <> uint8_t ntoh ( uint8_t);
template <> uint16_t ntoh (uint16_t);
template <> uint32_t ntoh (uint32_t);
template <> uint64_t ntoh (uint64_t);
#else
static void
byte_swap (uint8_t *restrict dst, uint8_t *restrict src, size_t len) {
for (unsigned int i = 0; i < len; ++i)
dst[len - i - 1] = src[i];
}
template <typename T>
T
hton (T i) {
// Unsure if this will really be sensible for non-intrinsic types, or types larger than 8 bytes.
static_assert (is_fundamental <T>::value, "hton implementation assumes fundamental types");
static_assert (is_unsigned <T>::value, "hton implementation does not handle signed");
T swapped;
byte_swap (reinterpret_cast <uint8_t*>(&swapped),
reinterpret_cast <uint8_t*>(&i),
sizeof (T));
return swapped;
}
template <typename T>
T
ntoh (T i) {
// Unsure if this will really be sensible for non-intrinsic types, or types larger than 8 bytes.
static_assert (is_fundamental <T>::value, "ntoh implementation assumes fundamental types");
static_assert (is_unsigned <T>::value, "ntoh implementation does not handle signed");
T swapped;
byte_swap (reinterpret_cast <uint8_t*>(&swapped),
reinterpret_cast <uint8_t*>(&i),
sizeof (T));
return swapped;
}
template <> uint8_t hton (uint8_t i) { return i; }
template <> uint8_t ntoh (uint8_t i) { return i; }
template uint16_t ntoh<uint16_t> (uint16_t);
template uint32_t ntoh<uint32_t> (uint32_t);
template uint64_t ntoh<uint64_t> (uint64_t);
template uint16_t hton<uint16_t> (uint16_t);
template uint32_t hton<uint32_t> (uint32_t);
template uint64_t hton<uint64_t> (uint64_t);
#endif