| 1 | // int_encoding.h -- variable length and unaligned integers -*- C++ -*- |
| 2 | |
| 3 | // Copyright (C) 2009-2018 Free Software Foundation, Inc. |
| 4 | // Written by Doug Kwan <dougkwan@google.com> by refactoring scattered |
| 5 | // contents from other files in gold. Original code written by Ian |
| 6 | // Lance Taylor <iant@google.com> and Caleb Howe <cshowe@google.com>. |
| 7 | |
| 8 | // This file is part of gold. |
| 9 | |
| 10 | // This program is free software; you can redistribute it and/or modify |
| 11 | // it under the terms of the GNU General Public License as published by |
| 12 | // the Free Software Foundation; either version 3 of the License, or |
| 13 | // (at your option) any later version. |
| 14 | |
| 15 | // This program is distributed in the hope that it will be useful, |
| 16 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 17 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 18 | // GNU General Public License for more details. |
| 19 | |
| 20 | // You should have received a copy of the GNU General Public License |
| 21 | // along with this program; if not, write to the Free Software |
| 22 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 23 | // MA 02110-1301, USA. |
| 24 | |
| 25 | #ifndef GOLD_INT_ENCODING_H |
| 26 | #define GOLD_INT_ENCODING_H |
| 27 | |
| 28 | #include <vector> |
| 29 | #include "elfcpp.h" |
| 30 | #include "target.h" |
| 31 | #include "parameters.h" |
| 32 | |
| 33 | namespace gold |
| 34 | { |
| 35 | |
| 36 | // |
| 37 | // LEB 128 encoding support. |
| 38 | // |
| 39 | |
| 40 | // Read a ULEB 128 encoded integer from BUFFER. Return the length of the |
| 41 | // encoded integer at the location PLEN. The common case of a single-byte |
| 42 | // value is handled inline, and multi-byte values are processed by the _x |
| 43 | // routine, where BYTE is the first byte of the value. |
| 44 | |
| 45 | uint64_t |
| 46 | read_unsigned_LEB_128_x(const unsigned char* buffer, size_t* plen, |
| 47 | unsigned char byte); |
| 48 | |
| 49 | inline uint64_t |
| 50 | read_unsigned_LEB_128(const unsigned char* buffer, size_t* plen) |
| 51 | { |
| 52 | unsigned char byte = *buffer++; |
| 53 | |
| 54 | if ((byte & 0x80) != 0) |
| 55 | return read_unsigned_LEB_128_x(buffer, plen, byte); |
| 56 | |
| 57 | *plen = 1; |
| 58 | return static_cast<uint64_t>(byte); |
| 59 | } |
| 60 | |
| 61 | // Read an SLEB 128 encoded integer from BUFFER. Return the length of the |
| 62 | // encoded integer at the location PLEN. The common case of a single-byte |
| 63 | // value is handled inline, and multi-byte values are processed by the _x |
| 64 | // routine, where BYTE is the first byte of the value. |
| 65 | |
| 66 | int64_t |
| 67 | read_signed_LEB_128_x(const unsigned char* buffer, size_t* plen, |
| 68 | unsigned char byte); |
| 69 | |
| 70 | inline int64_t |
| 71 | read_signed_LEB_128(const unsigned char* buffer, size_t* plen) |
| 72 | { |
| 73 | unsigned char byte = *buffer++; |
| 74 | |
| 75 | if ((byte & 0x80) != 0) |
| 76 | return read_signed_LEB_128_x(buffer, plen, byte); |
| 77 | |
| 78 | *plen = 1; |
| 79 | if (byte & 0x40) |
| 80 | return -(static_cast<int64_t>(1) << 7) | static_cast<int64_t>(byte); |
| 81 | return static_cast<int64_t>(byte); |
| 82 | } |
| 83 | |
| 84 | // Write a ULEB 128 encoded VALUE to BUFFER. |
| 85 | |
| 86 | void |
| 87 | write_unsigned_LEB_128(std::vector<unsigned char>* buffer, uint64_t value); |
| 88 | |
| 89 | // Return the ULEB 128 encoded size of VALUE. |
| 90 | |
| 91 | size_t |
| 92 | get_length_as_unsigned_LEB_128(uint64_t value); |
| 93 | |
| 94 | // |
| 95 | // Unaligned integer encoding support. |
| 96 | // |
| 97 | |
| 98 | // Insert VALSIZE-bit integer VALUE into DESTINATION. |
| 99 | |
| 100 | template <int valsize> |
| 101 | void insert_into_vector(std::vector<unsigned char>* destination, |
| 102 | typename elfcpp::Valtype_base<valsize>::Valtype value) |
| 103 | { |
| 104 | unsigned char buffer[valsize / 8]; |
| 105 | if (parameters->target().is_big_endian()) |
| 106 | elfcpp::Swap_unaligned<valsize, true>::writeval(buffer, value); |
| 107 | else |
| 108 | elfcpp::Swap_unaligned<valsize, false>::writeval(buffer, value); |
| 109 | destination->insert(destination->end(), buffer, buffer + valsize / 8); |
| 110 | } |
| 111 | |
| 112 | // Read a possibly unaligned integer of SIZE from SOURCE. |
| 113 | |
| 114 | template <int valsize> |
| 115 | typename elfcpp::Valtype_base<valsize>::Valtype |
| 116 | read_from_pointer(const unsigned char* source) |
| 117 | { |
| 118 | typename elfcpp::Valtype_base<valsize>::Valtype return_value; |
| 119 | if (parameters->target().is_big_endian()) |
| 120 | return_value = elfcpp::Swap_unaligned<valsize, true>::readval(source); |
| 121 | else |
| 122 | return_value = elfcpp::Swap_unaligned<valsize, false>::readval(source); |
| 123 | return return_value; |
| 124 | } |
| 125 | |
| 126 | // Read a possibly unaligned integer of SIZE. Update SOURCE after read. |
| 127 | |
| 128 | template <int valsize> |
| 129 | typename elfcpp::Valtype_base<valsize>::Valtype |
| 130 | read_from_pointer(unsigned char** source) |
| 131 | { |
| 132 | typename elfcpp::Valtype_base<valsize>::Valtype return_value; |
| 133 | if (parameters->target().is_big_endian()) |
| 134 | return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source); |
| 135 | else |
| 136 | return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source); |
| 137 | *source += valsize / 8; |
| 138 | return return_value; |
| 139 | } |
| 140 | |
| 141 | // Same as the above except for use with const unsigned char data. |
| 142 | |
| 143 | template <int valsize> |
| 144 | typename elfcpp::Valtype_base<valsize>::Valtype |
| 145 | read_from_pointer(const unsigned char** source) |
| 146 | { |
| 147 | typename elfcpp::Valtype_base<valsize>::Valtype return_value; |
| 148 | if (parameters->target().is_big_endian()) |
| 149 | return_value = elfcpp::Swap_unaligned<valsize, true>::readval(*source); |
| 150 | else |
| 151 | return_value = elfcpp::Swap_unaligned<valsize, false>::readval(*source); |
| 152 | *source += valsize / 8; |
| 153 | return return_value; |
| 154 | } |
| 155 | |
| 156 | } // End namespace gold. |
| 157 | |
| 158 | #endif // !defined(GOLD_INT_ENCODING_H) |