core/fxcrt/cfx_utf8encoder.cpp

// Copyright 2018 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 "core/fxcrt/cfx_utf8encoder.h"

CFX_UTF8Encoder::CFX_UTF8Encoder() = default;

CFX_UTF8Encoder::~CFX_UTF8Encoder() = default;

void CFX_UTF8Encoder::Input(wchar_t unicodeAsWchar) {
  uint32_t unicode = static_cast<uint32_t>(unicodeAsWchar);
  if (unicode < 0x80) {
    m_Buffer.push_back(unicode);
  } else {
    if (unicode >= 0x80000000)
      return;

    int nbytes = 0;
    if (unicode < 0x800)
      nbytes = 2;
    else if (unicode < 0x10000)
      nbytes = 3;
    else if (unicode < 0x200000)
      nbytes = 4;
    else if (unicode < 0x4000000)
      nbytes = 5;
    else
      nbytes = 6;

    static const uint8_t prefix[] = {0xc0, 0xe0, 0xf0, 0xf8, 0xfc};
    int order = 1 << ((nbytes - 1) * 6);
    int code = unicodeAsWchar;
    m_Buffer.push_back(prefix[nbytes - 2] | (code / order));
    for (int i = 0; i < nbytes - 1; i++) {
      code = code % order;
      order >>= 6;
      m_Buffer.push_back(0x80 | (code / order));
    }
  }
}