58 lines
2.0 KiB
C++
58 lines
2.0 KiB
C++
|
//===- llvm/BinaryFormat/COFF.cpp - The COFF format -----------------------===//
|
||
|
|
//
|
||
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
||
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
||
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
||
|
|
//
|
||
|
|
//===----------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
#include "llvm/BinaryFormat/COFF.h"
|
||
|
|
#include "llvm/ADT/SmallVector.h"
|
||
|
|
#include "llvm/ADT/Twine.h"
|
||
|
|
|
||
|
|
// Maximum offsets for different string table entry encodings.
|
||
|
|
enum : unsigned { Max7DecimalOffset = 9999999U };
|
||
|
|
enum : uint64_t { MaxBase64Offset = 0xFFFFFFFFFULL }; // 64^6, including 0
|
||
|
|
|
||
|
|
// Encode a string table entry offset in base 64, padded to 6 chars, and
|
||
|
|
// prefixed with a double slash: '//AAAAAA', '//AAAAAB', ...
|
||
|
|
// Buffer must be at least 8 bytes large. No terminating null appended.
|
||
|
|
static void encodeBase64StringEntry(char *Buffer, uint64_t Value) {
|
||
|
|
assert(Value > Max7DecimalOffset && Value <= MaxBase64Offset &&
|
||
|
|
"Illegal section name encoding for value");
|
||
|
|
|
||
|
|
static const char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
|
||
|
|
"abcdefghijklmnopqrstuvwxyz"
|
||
|
|
"0123456789+/";
|
||
|
|
|
||
|
|
Buffer[0] = '/';
|
||
|
|
Buffer[1] = '/';
|
||
|
|
|
||
|
|
char *Ptr = Buffer + 7;
|
||
|
|
for (unsigned i = 0; i < 6; ++i) {
|
||
|
|
unsigned Rem = Value % 64;
|
||
|
|
Value /= 64;
|
||
|
|
*(Ptr--) = Alphabet[Rem];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
bool llvm::COFF::encodeSectionName(char *Out, uint64_t Offset) {
|
||
|
|
if (Offset <= Max7DecimalOffset) {
|
||
|
|
// Offsets of 7 digits or less are encoded in ASCII.
|
||
|
|
SmallVector<char, COFF::NameSize> Buffer;
|
||
|
|
Twine('/').concat(Twine(Offset)).toVector(Buffer);
|
||
|
|
assert(Buffer.size() <= COFF::NameSize && Buffer.size() >= 2);
|
||
|
|
std::memcpy(Out, Buffer.data(), Buffer.size());
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (Offset <= MaxBase64Offset) {
|
||
|
|
// Starting with 10,000,000, offsets are encoded as base64.
|
||
|
|
encodeBase64StringEntry(Out, Offset);
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
|
||
|
|
// The offset is too large to be encoded.
|
||
|
|
return false;
|
||
|
|
}
|