llvm-6502/include/llvm/Support/Endian.h
Rafael Espindola 21a01d1ea8 Make the host endianness check an integer constant expression.
I will remove the isBigEndianHost function once I update clang.

The ifdef logic is designed to
* not use configure/cmake to avoid breaking -arch i686 -arch ppc.
* default to little endian
* be as small as possible

It looks like sys/endian.h is the preferred header on most modern BSD systems,
but it is better to change this in a followup patch as machine/endian.h is
available on FreeBSD, OpenBSD, NetBSD and OS X.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179527 91177308-0d34-0410-b5e6-96231b3b80d8
2013-04-15 14:44:24 +00:00

180 lines
6.8 KiB
C++

//===- Endian.h - Utilities for IO with endian specific data ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares generic functions to read and write endian specific data.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_ENDIAN_H
#define LLVM_SUPPORT_ENDIAN_H
#include "llvm/Support/AlignOf.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/SwapByteOrder.h"
#include "llvm/Support/type_traits.h"
namespace llvm {
namespace support {
enum endianness {big, little, native};
// These are named values for common alignments.
enum {aligned = 0, unaligned = 1};
namespace detail {
/// \brief ::value is either alignment, or alignof(T) if alignment is 0.
template<class T, int alignment>
struct PickAlignment {
enum {value = alignment == 0 ? AlignOf<T>::Alignment : alignment};
};
} // end namespace detail
namespace endian {
template<typename value_type, endianness endian>
inline value_type byte_swap(value_type value) {
if (endian != native && sys::IsBigEndianHost != (endian == big))
return sys::SwapByteOrder(value);
return value;
}
template<typename value_type,
endianness endian,
std::size_t alignment>
inline value_type read(const void *memory) {
value_type ret;
memcpy(&ret,
LLVM_ASSUME_ALIGNED(memory,
(detail::PickAlignment<value_type, alignment>::value)),
sizeof(value_type));
return byte_swap<value_type, endian>(ret);
}
template<typename value_type,
endianness endian,
std::size_t alignment>
inline void write(void *memory, value_type value) {
value = byte_swap<value_type, endian>(value);
memcpy(LLVM_ASSUME_ALIGNED(memory,
(detail::PickAlignment<value_type, alignment>::value)),
&value,
sizeof(value_type));
}
} // end namespace endian
namespace detail {
template<typename value_type,
endianness endian,
std::size_t alignment>
struct packed_endian_specific_integral {
operator value_type() const {
return endian::read<value_type, endian, alignment>(
(const void*)Value.buffer);
}
void operator=(value_type newValue) {
endian::write<value_type, endian, alignment>(
(void*)Value.buffer, newValue);
}
private:
AlignedCharArray<PickAlignment<value_type, alignment>::value,
sizeof(value_type)> Value;
};
} // end namespace detail
typedef detail::packed_endian_specific_integral
<uint8_t, little, unaligned> ulittle8_t;
typedef detail::packed_endian_specific_integral
<uint16_t, little, unaligned> ulittle16_t;
typedef detail::packed_endian_specific_integral
<uint32_t, little, unaligned> ulittle32_t;
typedef detail::packed_endian_specific_integral
<uint64_t, little, unaligned> ulittle64_t;
typedef detail::packed_endian_specific_integral
<int8_t, little, unaligned> little8_t;
typedef detail::packed_endian_specific_integral
<int16_t, little, unaligned> little16_t;
typedef detail::packed_endian_specific_integral
<int32_t, little, unaligned> little32_t;
typedef detail::packed_endian_specific_integral
<int64_t, little, unaligned> little64_t;
typedef detail::packed_endian_specific_integral
<uint8_t, little, aligned> aligned_ulittle8_t;
typedef detail::packed_endian_specific_integral
<uint16_t, little, aligned> aligned_ulittle16_t;
typedef detail::packed_endian_specific_integral
<uint32_t, little, aligned> aligned_ulittle32_t;
typedef detail::packed_endian_specific_integral
<uint64_t, little, aligned> aligned_ulittle64_t;
typedef detail::packed_endian_specific_integral
<int8_t, little, aligned> aligned_little8_t;
typedef detail::packed_endian_specific_integral
<int16_t, little, aligned> aligned_little16_t;
typedef detail::packed_endian_specific_integral
<int32_t, little, aligned> aligned_little32_t;
typedef detail::packed_endian_specific_integral
<int64_t, little, aligned> aligned_little64_t;
typedef detail::packed_endian_specific_integral
<uint8_t, big, unaligned> ubig8_t;
typedef detail::packed_endian_specific_integral
<uint16_t, big, unaligned> ubig16_t;
typedef detail::packed_endian_specific_integral
<uint32_t, big, unaligned> ubig32_t;
typedef detail::packed_endian_specific_integral
<uint64_t, big, unaligned> ubig64_t;
typedef detail::packed_endian_specific_integral
<int8_t, big, unaligned> big8_t;
typedef detail::packed_endian_specific_integral
<int16_t, big, unaligned> big16_t;
typedef detail::packed_endian_specific_integral
<int32_t, big, unaligned> big32_t;
typedef detail::packed_endian_specific_integral
<int64_t, big, unaligned> big64_t;
typedef detail::packed_endian_specific_integral
<uint8_t, big, aligned> aligned_ubig8_t;
typedef detail::packed_endian_specific_integral
<uint16_t, big, aligned> aligned_ubig16_t;
typedef detail::packed_endian_specific_integral
<uint32_t, big, aligned> aligned_ubig32_t;
typedef detail::packed_endian_specific_integral
<uint64_t, big, aligned> aligned_ubig64_t;
typedef detail::packed_endian_specific_integral
<int8_t, big, aligned> aligned_big8_t;
typedef detail::packed_endian_specific_integral
<int16_t, big, aligned> aligned_big16_t;
typedef detail::packed_endian_specific_integral
<int32_t, big, aligned> aligned_big32_t;
typedef detail::packed_endian_specific_integral
<int64_t, big, aligned> aligned_big64_t;
typedef detail::packed_endian_specific_integral
<uint16_t, native, unaligned> unaligned_uint16_t;
typedef detail::packed_endian_specific_integral
<uint32_t, native, unaligned> unaligned_uint32_t;
typedef detail::packed_endian_specific_integral
<uint64_t, native, unaligned> unaligned_uint64_t;
typedef detail::packed_endian_specific_integral
<int16_t, native, unaligned> unaligned_int16_t;
typedef detail::packed_endian_specific_integral
<int32_t, native, unaligned> unaligned_int32_t;
typedef detail::packed_endian_specific_integral
<int64_t, native, unaligned> unaligned_int64_t;
} // end namespace llvm
} // end namespace support
#endif