text: // Copyright 2014 PDFium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
  
  #include <algorithm>
  #include <limits>
  
  #include "core/fxcrt/fx_basic.h"
  #include "core/fxcrt/fx_safe_types.h"
  #include "third_party/base/numerics/safe_conversions.h"
  
  CFX_BinaryBuf::CFX_BinaryBuf()
      : m_AllocStep(0), m_AllocSize(0), m_DataSize(0) {}
  
  CFX_BinaryBuf::CFX_BinaryBuf(FX_STRSIZE size)
      : m_AllocStep(0), m_AllocSize(size), m_DataSize(size) {
    m_pBuffer.reset(FX_Alloc(uint8_t, size));
  }
  
  CFX_BinaryBuf::~CFX_BinaryBuf() {}
  
  void CFX_BinaryBuf::Delete(int start_index, int count) {
    if (!m_pBuffer || start_index < 0 || count < 0 || count > m_DataSize ||
        start_index > m_DataSize - count) {
      return;
    }
    FXSYS_memmove(m_pBuffer.get() + start_index,
                  m_pBuffer.get() + start_index + count,
                  m_DataSize - start_index - count);
    m_DataSize -= count;
  }
  
  void CFX_BinaryBuf::Clear() {
    m_DataSize = 0;
  }
  
  uint8_t* CFX_BinaryBuf::DetachBuffer() {
    m_DataSize = 0;
    m_AllocSize = 0;
    return m_pBuffer.release();
  }
  
  void CFX_BinaryBuf::AttachData(uint8_t* buffer, FX_STRSIZE size) {
    m_pBuffer.reset(buffer);
    m_DataSize = size;
    m_AllocSize = size;
  }
  
  void CFX_BinaryBuf::EstimateSize(FX_STRSIZE size, FX_STRSIZE step) {
    m_AllocStep = step;
    if (m_AllocSize < size)
      ExpandBuf(size - m_DataSize);
  }
  
  void CFX_BinaryBuf::ExpandBuf(FX_STRSIZE add_size) {
    FX_SAFE_STRSIZE new_size = m_DataSize;
    new_size += add_size;
    if (m_AllocSize >= new_size.ValueOrDie())
      return;
  
    int alloc_step = std::max(128, m_AllocStep ? m_AllocStep : m_AllocSize / 4);
    new_size += alloc_step - 1;  // Quantize, don't combine these lines.
    new_size /= alloc_step;
    new_size *= alloc_step;
    m_AllocSize = new_size.ValueOrDie();
    m_pBuffer.reset(m_pBuffer
                        ? FX_Realloc(uint8_t, m_pBuffer.release(), m_AllocSize)
                        : FX_Alloc(uint8_t, m_AllocSize));
  }
  
  void CFX_BinaryBuf::AppendBlock(const void* pBuf, FX_STRSIZE size) {
    if (size <= 0)
      return;
  
    ExpandBuf(size);
    if (pBuf) {
      FXSYS_memcpy(m_pBuffer.get() + m_DataSize, pBuf, size);
    } else {
      FXSYS_memset(m_pBuffer.get() + m_DataSize, 0, size);
    }
    m_DataSize += size;
  }
  
  void CFX_BinaryBuf::InsertBlock(FX_STRSIZE pos,
                                  const void* pBuf,
                                  FX_STRSIZE size) {
    if (size <= 0)
      return;
  
    ExpandBuf(size);
    FXSYS_memmove(m_pBuffer.get() + pos + size, m_pBuffer.get() + pos,
                  m_DataSize - pos);
    if (pBuf) {
      FXSYS_memcpy(m_pBuffer.get() + pos, pBuf, size);
    } else {
      FXSYS_memset(m_pBuffer.get() + pos, 0, size);
    }
    m_DataSize += size;
  }
  
  CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(const CFX_ByteStringC& lpsz) {
    AppendBlock(lpsz.raw_str(), lpsz.GetLength());
    return *this;
  }
  
  CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(int i) {
    char buf[32];
    FXSYS_itoa(i, buf, 10);
    AppendBlock(buf, FXSYS_strlen(buf));
    return *this;
  }
  
  CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(uint32_t i) {
    char buf[32];
    FXSYS_itoa(i, buf, 10);
    AppendBlock(buf, FXSYS_strlen(buf));
    return *this;
  }
  
  CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(double f) {
    char buf[32];
    FX_STRSIZE len = FX_ftoa((FX_FLOAT)f, buf);
    AppendBlock(buf, len);
    return *this;
  }
  
  CFX_ByteTextBuf& CFX_ByteTextBuf::operator<<(const CFX_ByteTextBuf& buf) {
    AppendBlock(buf.m_pBuffer.get(), buf.m_DataSize);
    return *this;
  }
  
  void CFX_WideTextBuf::AppendChar(FX_WCHAR ch) {
    ExpandBuf(sizeof(FX_WCHAR));
    *(FX_WCHAR*)(m_pBuffer.get() + m_DataSize) = ch;
    m_DataSize += sizeof(FX_WCHAR);
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideStringC& str) {
    AppendBlock(str.c_str(), str.GetLength() * sizeof(FX_WCHAR));
    return *this;
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideString& str) {
    AppendBlock(str.c_str(), str.GetLength() * sizeof(FX_WCHAR));
    return *this;
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(int i) {
    char buf[32];
    FXSYS_itoa(i, buf, 10);
    FX_STRSIZE len = FXSYS_strlen(buf);
    ExpandBuf(len * sizeof(FX_WCHAR));
    FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer.get() + m_DataSize);
    for (FX_STRSIZE j = 0; j < len; j++) {
      *str++ = buf[j];
    }
    m_DataSize += len * sizeof(FX_WCHAR);
    return *this;
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(double f) {
    char buf[32];
    FX_STRSIZE len = FX_ftoa((FX_FLOAT)f, buf);
    ExpandBuf(len * sizeof(FX_WCHAR));
    FX_WCHAR* str = (FX_WCHAR*)(m_pBuffer.get() + m_DataSize);
    for (FX_STRSIZE i = 0; i < len; i++) {
      *str++ = buf[i];
    }
    m_DataSize += len * sizeof(FX_WCHAR);
    return *this;
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const FX_WCHAR* lpsz) {
    AppendBlock(lpsz, FXSYS_wcslen(lpsz) * sizeof(FX_WCHAR));
    return *this;
  }
  
  CFX_WideTextBuf& CFX_WideTextBuf::operator<<(const CFX_WideTextBuf& buf) {
    AppendBlock(buf.m_pBuffer.get(), buf.m_DataSize);
    return *this;
  }
  
  void CFX_BitStream::Init(const uint8_t* pData, uint32_t dwSize) {
    m_pData = pData;
    m_BitSize = dwSize * 8;
    m_BitPos = 0;
  }
  
  void CFX_BitStream::ByteAlign() {
    m_BitPos = (m_BitPos + 7) & ~7;
  }
  
  uint32_t CFX_BitStream::GetBits(uint32_t nBits) {
    if (nBits > m_BitSize || m_BitPos + nBits > m_BitSize)
      return 0;
  
    if (nBits == 1) {
      int bit = (m_pData[m_BitPos / 8] & (1 << (7 - m_BitPos % 8))) ? 1 : 0;
      m_BitPos++;
      return bit;
    }
  
    uint32_t byte_pos = m_BitPos / 8;
    uint32_t bit_pos = m_BitPos % 8;
    uint32_t bit_left = nBits;
    uint32_t result = 0;
    if (bit_pos) {
      if (8 - bit_pos >= bit_left) {
        result =
            (m_pData[byte_pos] & (0xff >> bit_pos)) >> (8 - bit_pos - bit_left);
        m_BitPos += bit_left;
        return result;
      }
      bit_left -= 8 - bit_pos;
      result = (m_pData[byte_pos++] & ((1 << (8 - bit_pos)) - 1)) << bit_left;
    }
    while (bit_left >= 8) {
      bit_left -= 8;
      result |= m_pData[byte_pos++] << bit_left;
    }
    if (bit_left)
      result |= m_pData[byte_pos] >> (8 - bit_left);
    m_BitPos += nBits;
    return result;
  }
  
  CFX_FileBufferArchive::CFX_FileBufferArchive()
      : m_Length(0), m_pFile(nullptr) {}
  
  CFX_FileBufferArchive::~CFX_FileBufferArchive() {}
  
  void CFX_FileBufferArchive::Clear() {
    m_Length = 0;
    m_pBuffer.reset();
    m_pFile = nullptr;
  }
  
  bool CFX_FileBufferArchive::Flush() {
    size_t nRemaining = m_Length;
    m_Length = 0;
    if (!m_pFile)
      return false;
    if (!m_pBuffer || !nRemaining)
      return true;
    return m_pFile->WriteBlock(m_pBuffer.get(), nRemaining) > 0;
  }
  
  int32_t CFX_FileBufferArchive::AppendBlock(const void* pBuf, size_t size) {
    if (!pBuf || size < 1)
      return 0;
  
    if (!m_pBuffer)
      m_pBuffer.reset(FX_Alloc(uint8_t, kBufSize));
  
    const uint8_t* buffer = reinterpret_cast<const uint8_t*>(pBuf);
    size_t temp_size = size;
    while (temp_size) {
      size_t buf_size = std::min(kBufSize - m_Length, temp_size);
      FXSYS_memcpy(m_pBuffer.get() + m_Length, buffer, buf_size);
      m_Length += buf_size;
      if (m_Length == kBufSize) {
        if (!Flush()) {
          return -1;
        }
      }
      temp_size -= buf_size;
      buffer += buf_size;
    }
    return pdfium::base::checked_cast<int32_t>(size);
  }
  
  int32_t CFX_FileBufferArchive::AppendByte(uint8_t byte) {
    return AppendBlock(&byte, 1);
  }
  
  int32_t CFX_FileBufferArchive::AppendDWord(uint32_t i) {
    char buf[32];
    FXSYS_itoa(i, buf, 10);
    return AppendBlock(buf, (size_t)FXSYS_strlen(buf));
  }
  
  int32_t CFX_FileBufferArchive::AppendString(const CFX_ByteStringC& lpsz) {
    return AppendBlock(lpsz.raw_str(), lpsz.GetLength());
  }
  
  void CFX_FileBufferArchive::AttachFile(IFX_StreamWrite* pFile) {
    ASSERT(pFile);
    m_pFile = pFile;
  }
  