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llvm-mirror/include/llvm/Support/Endian.h
Zachary Turner 9c3f04dc50 iwyu fixes for lldbCore.
This adjusts header file includes for headers and source files
in Core.  In doing so, one dependency cycle is eliminated
because all the includes from Core to that project were dead
includes anyway.  In places where some files in other projects
were only compiling due to a transitive include from another
header, fixups have been made so that those files also include
the header they need.  Tested on Windows and Linux, and plan
to address failures on OSX and FreeBSD after watching the
bots.

llvm-svn: 299714
2017-04-06 21:28:29 +00:00

402 lines
14 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/Host.h"
#include "llvm/Support/SwapByteOrder.h"
#include <stdint.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 };
};
} // end namespace detail
namespace endian {
constexpr endianness system_endianness() {
return sys::IsBigEndianHost ? big : little;
}
template <typename value_type>
inline value_type byte_swap(value_type value, endianness endian) {
if ((endian != native) && (endian != system_endianness()))
sys::swapByteOrder(value);
return value;
}
/// Swap the bytes of value to match the given endianness.
template<typename value_type, endianness endian>
inline value_type byte_swap(value_type value) {
return byte_swap(value, endian);
}
/// Read a value of a particular endianness from memory.
template <typename value_type, std::size_t alignment>
inline value_type read(const void *memory, endianness endian) {
value_type ret;
memcpy(&ret,
LLVM_ASSUME_ALIGNED(
memory, (detail::PickAlignment<value_type, alignment>::value)),
sizeof(value_type));
return byte_swap<value_type>(ret, endian);
}
template<typename value_type,
endianness endian,
std::size_t alignment>
inline value_type read(const void *memory) {
return read<value_type, alignment>(memory, endian);
}
/// Read a value of a particular endianness from a buffer, and increment the
/// buffer past that value.
template <typename value_type, std::size_t alignment, typename CharT>
inline value_type readNext(const CharT *&memory, endianness endian) {
value_type ret = read<value_type, alignment>(memory, endian);
memory += sizeof(value_type);
return ret;
}
template<typename value_type, endianness endian, std::size_t alignment,
typename CharT>
inline value_type readNext(const CharT *&memory) {
return readNext<value_type, alignment, CharT>(memory, endian);
}
/// Write a value to memory with a particular endianness.
template <typename value_type, std::size_t alignment>
inline void write(void *memory, value_type value, endianness endian) {
value = byte_swap<value_type>(value, endian);
memcpy(LLVM_ASSUME_ALIGNED(
memory, (detail::PickAlignment<value_type, alignment>::value)),
&value, sizeof(value_type));
}
template<typename value_type,
endianness endian,
std::size_t alignment>
inline void write(void *memory, value_type value) {
write<value_type, alignment>(memory, value, endian);
}
template <typename value_type>
using make_unsigned_t = typename std::make_unsigned<value_type>::type;
/// Read a value of a particular endianness from memory, for a location
/// that starts at the given bit offset within the first byte.
template <typename value_type, endianness endian, std::size_t alignment>
inline value_type readAtBitAlignment(const void *memory, uint64_t startBit) {
assert(startBit < 8);
if (startBit == 0)
return read<value_type, endian, alignment>(memory);
else {
// Read two values and compose the result from them.
value_type val[2];
memcpy(&val[0],
LLVM_ASSUME_ALIGNED(
memory, (detail::PickAlignment<value_type, alignment>::value)),
sizeof(value_type) * 2);
val[0] = byte_swap<value_type, endian>(val[0]);
val[1] = byte_swap<value_type, endian>(val[1]);
// Shift bits from the lower value into place.
make_unsigned_t<value_type> lowerVal = val[0] >> startBit;
// Mask off upper bits after right shift in case of signed type.
make_unsigned_t<value_type> numBitsFirstVal =
(sizeof(value_type) * 8) - startBit;
lowerVal &= ((make_unsigned_t<value_type>)1 << numBitsFirstVal) - 1;
// Get the bits from the upper value.
make_unsigned_t<value_type> upperVal =
val[1] & (((make_unsigned_t<value_type>)1 << startBit) - 1);
// Shift them in to place.
upperVal <<= numBitsFirstVal;
return lowerVal | upperVal;
}
}
/// Write a value to memory with a particular endianness, for a location
/// that starts at the given bit offset within the first byte.
template <typename value_type, endianness endian, std::size_t alignment>
inline void writeAtBitAlignment(void *memory, value_type value,
uint64_t startBit) {
assert(startBit < 8);
if (startBit == 0)
write<value_type, endian, alignment>(memory, value);
else {
// Read two values and shift the result into them.
value_type val[2];
memcpy(&val[0],
LLVM_ASSUME_ALIGNED(
memory, (detail::PickAlignment<value_type, alignment>::value)),
sizeof(value_type) * 2);
val[0] = byte_swap<value_type, endian>(val[0]);
val[1] = byte_swap<value_type, endian>(val[1]);
// Mask off any existing bits in the upper part of the lower value that
// we want to replace.
val[0] &= ((make_unsigned_t<value_type>)1 << startBit) - 1;
make_unsigned_t<value_type> numBitsFirstVal =
(sizeof(value_type) * 8) - startBit;
make_unsigned_t<value_type> lowerVal = value;
if (startBit > 0) {
// Mask off the upper bits in the new value that are not going to go into
// the lower value. This avoids a left shift of a negative value, which
// is undefined behavior.
lowerVal &= (((make_unsigned_t<value_type>)1 << numBitsFirstVal) - 1);
// Now shift the new bits into place
lowerVal <<= startBit;
}
val[0] |= lowerVal;
// Mask off any existing bits in the lower part of the upper value that
// we want to replace.
val[1] &= ~(((make_unsigned_t<value_type>)1 << startBit) - 1);
// Next shift the bits that go into the upper value into position.
make_unsigned_t<value_type> upperVal = value >> numBitsFirstVal;
// Mask off upper bits after right shift in case of signed type.
upperVal &= ((make_unsigned_t<value_type>)1 << startBit) - 1;
val[1] |= upperVal;
// Finally, rewrite values.
val[0] = byte_swap<value_type, endian>(val[0]);
val[1] = byte_swap<value_type, endian>(val[1]);
memcpy(LLVM_ASSUME_ALIGNED(
memory, (detail::PickAlignment<value_type, alignment>::value)),
&val[0], sizeof(value_type) * 2);
}
}
} // end namespace endian
namespace detail {
template<typename value_type,
endianness endian,
std::size_t alignment>
struct packed_endian_specific_integral {
packed_endian_specific_integral() = default;
explicit packed_endian_specific_integral(value_type val) { *this = val; }
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);
}
packed_endian_specific_integral &operator+=(value_type newValue) {
*this = *this + newValue;
return *this;
}
packed_endian_specific_integral &operator-=(value_type newValue) {
*this = *this - newValue;
return *this;
}
packed_endian_specific_integral &operator|=(value_type newValue) {
*this = *this | newValue;
return *this;
}
packed_endian_specific_integral &operator&=(value_type newValue) {
*this = *this & newValue;
return *this;
}
private:
AlignedCharArray<PickAlignment<value_type, alignment>::value,
sizeof(value_type)> Value;
public:
struct ref {
explicit ref(void *Ptr) : Ptr(Ptr) {}
operator value_type() const {
return endian::read<value_type, endian, alignment>(Ptr);
}
void operator=(value_type NewValue) {
endian::write<value_type, endian, alignment>(Ptr, NewValue);
}
private:
void *Ptr;
};
};
} // end namespace detail
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
<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
<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
<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
<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
<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
<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
<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;
namespace endian {
template <typename T> inline T read(const void *P, endianness E) {
return read<T, unaligned>(P, E);
}
template <typename T, endianness E> inline T read(const void *P) {
return *(const detail::packed_endian_specific_integral<T, E, unaligned> *)P;
}
inline uint16_t read16(const void *P, endianness E) {
return read<uint16_t>(P, E);
}
inline uint32_t read32(const void *P, endianness E) {
return read<uint32_t>(P, E);
}
inline uint64_t read64(const void *P, endianness E) {
return read<uint64_t>(P, E);
}
template <endianness E> inline uint16_t read16(const void *P) {
return read<uint16_t, E>(P);
}
template <endianness E> inline uint32_t read32(const void *P) {
return read<uint32_t, E>(P);
}
template <endianness E> inline uint64_t read64(const void *P) {
return read<uint64_t, E>(P);
}
inline uint16_t read16le(const void *P) { return read16<little>(P); }
inline uint32_t read32le(const void *P) { return read32<little>(P); }
inline uint64_t read64le(const void *P) { return read64<little>(P); }
inline uint16_t read16be(const void *P) { return read16<big>(P); }
inline uint32_t read32be(const void *P) { return read32<big>(P); }
inline uint64_t read64be(const void *P) { return read64<big>(P); }
template <typename T> inline void write(void *P, T V, endianness E) {
write<T, unaligned>(P, V, E);
}
template <typename T, endianness E> inline void write(void *P, T V) {
*(detail::packed_endian_specific_integral<T, E, unaligned> *)P = V;
}
inline void write16(void *P, uint16_t V, endianness E) {
write<uint16_t>(P, V, E);
}
inline void write32(void *P, uint32_t V, endianness E) {
write<uint32_t>(P, V, E);
}
inline void write64(void *P, uint64_t V, endianness E) {
write<uint64_t>(P, V, E);
}
template <endianness E> inline void write16(void *P, uint16_t V) {
write<uint16_t, E>(P, V);
}
template <endianness E> inline void write32(void *P, uint32_t V) {
write<uint32_t, E>(P, V);
}
template <endianness E> inline void write64(void *P, uint64_t V) {
write<uint64_t, E>(P, V);
}
inline void write16le(void *P, uint16_t V) { write16<little>(P, V); }
inline void write32le(void *P, uint32_t V) { write32<little>(P, V); }
inline void write64le(void *P, uint64_t V) { write64<little>(P, V); }
inline void write16be(void *P, uint16_t V) { write16<big>(P, V); }
inline void write32be(void *P, uint32_t V) { write32<big>(P, V); }
inline void write64be(void *P, uint64_t V) { write64<big>(P, V); }
} // end namespace endian
} // end namespace support
} // end namespace llvm
#endif