contrib/llvm/lib/Support/BinaryStreamWriter.cpp

   1 //===- BinaryStreamWriter.cpp - Writes objects to a BinaryStream ----------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #include "llvm/Support/BinaryStreamWriter.h"
  11
  12 #include "llvm/Support/BinaryStreamError.h"
  13 #include "llvm/Support/BinaryStreamReader.h"
  14 #include "llvm/Support/BinaryStreamRef.h"
  15
  16 using namespace llvm;
  17
  18 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStreamRef Ref)
  19     : Stream(Ref) {}
  20
  21 BinaryStreamWriter::BinaryStreamWriter(WritableBinaryStream &Stream)
  22     : Stream(Stream) {}
  23
  24 BinaryStreamWriter::BinaryStreamWriter(MutableArrayRef<uint8_t> Data,
  25                                        llvm::support::endianness Endian)
  26     : Stream(Data, Endian) {}
  27
  28 Error BinaryStreamWriter::writeBytes(ArrayRef<uint8_t> Buffer) {
  29   if (auto EC = Stream.writeBytes(Offset, Buffer))
  30     return EC;
  31   Offset += Buffer.size();
  32   return Error::success();
  33 }
  34
  35 Error BinaryStreamWriter::writeCString(StringRef Str) {
  36   if (auto EC = writeFixedString(Str))
  37     return EC;
  38   if (auto EC = writeObject('\0'))
  39     return EC;
  40
  41   return Error::success();
  42 }
  43
  44 Error BinaryStreamWriter::writeFixedString(StringRef Str) {
  45   return writeBytes(ArrayRef<uint8_t>(Str.bytes_begin(), Str.bytes_end()));
  46 }
  47
  48 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref) {
  49   return writeStreamRef(Ref, Ref.getLength());
  50 }
  51
  52 Error BinaryStreamWriter::writeStreamRef(BinaryStreamRef Ref, uint32_t Length) {
  53   BinaryStreamReader SrcReader(Ref.slice(0, Length));
  54   // This is a bit tricky.  If we just call readBytes, we are requiring that it
  55   // return us the entire stream as a contiguous buffer.  There is no guarantee
  56   // this can be satisfied by returning a reference straight from the buffer, as
  57   // an implementation may not store all data in a single contiguous buffer.  So
  58   // we iterate over each contiguous chunk, writing each one in succession.
  59   while (SrcReader.bytesRemaining() > 0) {
  60     ArrayRef<uint8_t> Chunk;
  61     if (auto EC = SrcReader.readLongestContiguousChunk(Chunk))
  62       return EC;
  63     if (auto EC = writeBytes(Chunk))
  64       return EC;
  65   }
  66   return Error::success();
  67 }
  68
  69 std::pair<BinaryStreamWriter, BinaryStreamWriter>
  70 BinaryStreamWriter::split(uint32_t Off) const {
  71   assert(getLength() >= Off);
  72
  73   WritableBinaryStreamRef First = Stream.drop_front(Offset);
  74
  75   WritableBinaryStreamRef Second = First.drop_front(Off);
  76   First = First.keep_front(Off);
  77   BinaryStreamWriter W1{First};
  78   BinaryStreamWriter W2{Second};
  79   return std::make_pair(W1, W2);
  80 }
  81
  82 Error BinaryStreamWriter::padToAlignment(uint32_t Align) {
  83   uint32_t NewOffset = alignTo(Offset, Align);
  84   if (NewOffset > getLength())
  85     return make_error<BinaryStreamError>(stream_error_code::stream_too_short);
  86   while (Offset < NewOffset)
  87     if (auto EC = writeInteger('\0'))
  88       return EC;
  89   return Error::success();
  90 }