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93065647b8
This adds a function to Endian.h that reads from and updates a pointer into a buffer with endian specific data. This is more convenient for stream-like reading of data than endian::read. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204693 91177308-0d34-0410-b5e6-96231b3b80d8
191 lines
7.3 KiB
C++
191 lines
7.3 KiB
C++
//===- Endian.h - Utilities for IO with endian specific data ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares generic functions to read and write endian specific data.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_ENDIAN_H
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#define LLVM_SUPPORT_ENDIAN_H
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#include "llvm/Support/AlignOf.h"
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#include "llvm/Support/Host.h"
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#include "llvm/Support/SwapByteOrder.h"
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namespace llvm {
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namespace support {
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enum endianness {big, little, native};
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// These are named values for common alignments.
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enum {aligned = 0, unaligned = 1};
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namespace detail {
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/// \brief ::value is either alignment, or alignof(T) if alignment is 0.
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template<class T, int alignment>
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struct PickAlignment {
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enum {value = alignment == 0 ? AlignOf<T>::Alignment : alignment};
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};
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} // end namespace detail
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namespace endian {
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/// Swap the bytes of value to match the given endianness.
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template<typename value_type, endianness endian>
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inline value_type byte_swap(value_type value) {
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if (endian != native && sys::IsBigEndianHost != (endian == big))
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return sys::SwapByteOrder(value);
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return value;
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}
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/// Read a value of a particular endianness from memory.
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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inline value_type read(const void *memory) {
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value_type ret;
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memcpy(&ret,
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LLVM_ASSUME_ALIGNED(memory,
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(detail::PickAlignment<value_type, alignment>::value)),
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sizeof(value_type));
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return byte_swap<value_type, endian>(ret);
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}
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/// Read a value of a particular endianness from a buffer, and increment the
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/// buffer past that value.
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template<typename value_type, endianness endian, std::size_t alignment>
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inline value_type readNext(const unsigned char *&memory) {
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value_type ret = read<value_type, endian, alignment>(memory);
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memory += sizeof(value_type);
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return ret;
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}
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/// Write a value to memory with a particular endianness.
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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inline void write(void *memory, value_type value) {
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value = byte_swap<value_type, endian>(value);
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memcpy(LLVM_ASSUME_ALIGNED(memory,
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(detail::PickAlignment<value_type, alignment>::value)),
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&value,
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sizeof(value_type));
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}
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} // end namespace endian
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namespace detail {
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template<typename value_type,
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endianness endian,
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std::size_t alignment>
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struct packed_endian_specific_integral {
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operator value_type() const {
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return endian::read<value_type, endian, alignment>(
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(const void*)Value.buffer);
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}
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void operator=(value_type newValue) {
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endian::write<value_type, endian, alignment>(
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(void*)Value.buffer, newValue);
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}
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private:
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AlignedCharArray<PickAlignment<value_type, alignment>::value,
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sizeof(value_type)> Value;
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};
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} // end namespace detail
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typedef detail::packed_endian_specific_integral
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<uint8_t, little, unaligned> ulittle8_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, little, unaligned> ulittle16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, little, unaligned> ulittle32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, little, unaligned> ulittle64_t;
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typedef detail::packed_endian_specific_integral
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<int8_t, little, unaligned> little8_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, little, unaligned> little16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, little, unaligned> little32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, little, unaligned> little64_t;
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typedef detail::packed_endian_specific_integral
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<uint8_t, little, aligned> aligned_ulittle8_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, little, aligned> aligned_ulittle16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, little, aligned> aligned_ulittle32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, little, aligned> aligned_ulittle64_t;
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typedef detail::packed_endian_specific_integral
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<int8_t, little, aligned> aligned_little8_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, little, aligned> aligned_little16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, little, aligned> aligned_little32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, little, aligned> aligned_little64_t;
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typedef detail::packed_endian_specific_integral
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<uint8_t, big, unaligned> ubig8_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, big, unaligned> ubig16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, big, unaligned> ubig32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, big, unaligned> ubig64_t;
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typedef detail::packed_endian_specific_integral
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<int8_t, big, unaligned> big8_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, big, unaligned> big16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, big, unaligned> big32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, big, unaligned> big64_t;
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typedef detail::packed_endian_specific_integral
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<uint8_t, big, aligned> aligned_ubig8_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, big, aligned> aligned_ubig16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, big, aligned> aligned_ubig32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, big, aligned> aligned_ubig64_t;
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typedef detail::packed_endian_specific_integral
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<int8_t, big, aligned> aligned_big8_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, big, aligned> aligned_big16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, big, aligned> aligned_big32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, big, aligned> aligned_big64_t;
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typedef detail::packed_endian_specific_integral
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<uint16_t, native, unaligned> unaligned_uint16_t;
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typedef detail::packed_endian_specific_integral
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<uint32_t, native, unaligned> unaligned_uint32_t;
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typedef detail::packed_endian_specific_integral
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<uint64_t, native, unaligned> unaligned_uint64_t;
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typedef detail::packed_endian_specific_integral
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<int16_t, native, unaligned> unaligned_int16_t;
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typedef detail::packed_endian_specific_integral
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<int32_t, native, unaligned> unaligned_int32_t;
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typedef detail::packed_endian_specific_integral
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<int64_t, native, unaligned> unaligned_int64_t;
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} // end namespace llvm
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} // end namespace support
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#endif
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