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vcmi/lib/vcmi_endian.h

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/*
* vcmi_endian.h, part of VCMI engine
*
* Authors: listed in file AUTHORS in main folder
*
* License: GNU General Public License v2.0 or later
* Full text of license available in license.txt file, in main folder
*
*/
#pragma once
#include <boost/endian/conversion.hpp> //FIXME: use std::byteswap in C++23
VCMI_LIB_NAMESPACE_BEGIN
/* Reading values from memory.
*
* read_le_u16, read_le_u32 : read a little endian value from
* memory. On big endian machines, the value will be byteswapped.
*/
#if defined(__clang__) || defined(__GNUC__) || defined(_MSC_VER)
#if defined(_MSC_VER)
#define PACKED_STRUCT_BEGIN __pragma( pack(push, 1) )
#define PACKED_STRUCT_END __pragma( pack(pop) )
#else
#define PACKED_STRUCT_BEGIN
#define PACKED_STRUCT_END __attribute__(( packed ))
#endif
PACKED_STRUCT_BEGIN struct unaligned_Uint16 { ui16 val; } PACKED_STRUCT_END;
PACKED_STRUCT_BEGIN struct unaligned_Uint32 { ui32 val; } PACKED_STRUCT_END;
static inline ui16 read_unaligned_u16(const void *p)
{
const struct unaligned_Uint16 *v = reinterpret_cast<const struct unaligned_Uint16 *>(p);
return v->val;
}
static inline ui32 read_unaligned_u32(const void *p)
{
const struct unaligned_Uint32 *v = reinterpret_cast<const struct unaligned_Uint32 *>(p);
return v->val;
}
#define read_le_u16(p) (boost::endian::native_to_little(read_unaligned_u16(p)))
#define read_le_u32(p) (boost::endian::native_to_little(read_unaligned_u32(p)))
#else
#warning UB: unaligned memory access
#define read_le_u16(p) (boost::endian::native_to_little(* reinterpret_cast<const ui16 *>(p)))
#define read_le_u32(p) (boost::endian::native_to_little(* reinterpret_cast<const ui32 *>(p)))
#define PACKED_STRUCT_BEGIN
#define PACKED_STRUCT_END
#endif
static inline char readChar(const ui8 * buffer, int & i)
{
return buffer[i++];
}
static inline std::string readString(const ui8 * buffer, int & i)
{
int len = read_le_u32(buffer + i);
i += 4;
assert(len >= 0 && len <= 500000); //not too long
std::string ret;
ret.reserve(len);
for(int gg = 0; gg < len; ++gg)
{
ret += buffer[i++];
}
return ret;
}
VCMI_LIB_NAMESPACE_END