dom/base/ZLibHelper.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef DOM_ZLIBHELPER_H_
   8 #define DOM_ZLIBHELPER_H_
   9
  10 #include "js/TypeDecls.h"
  11 #include "zlib.h"
  12
  13 #include "mozilla/dom/CompressionStreamBinding.h"
  14
  15 namespace mozilla::dom {
  16
  17 // From the docs in
  18 // https://searchfox.org/mozilla-central/source/modules/zlib/src/zlib.h
  19 inline int8_t ZLibWindowBits(CompressionFormat format) {
  20   switch (format) {
  21     case CompressionFormat::Deflate:
  22       // The windowBits parameter is the base two logarithm of the window size
  23       // (the size of the history buffer). It should be in the range 8..15 for
  24       // this version of the library. Larger values of this parameter result
  25       // in better compression at the expense of memory usage.
  26       return 15;
  27     case CompressionFormat::Deflate_raw:
  28       // windowBits can also be –8..–15 for raw deflate. In this case,
  29       // -windowBits determines the window size.
  30       return -15;
  31     case CompressionFormat::Gzip:
  32       // windowBits can also be greater than 15 for optional gzip encoding.
  33       // Add 16 to windowBits to write a simple gzip header and trailer around
  34       // the compressed data instead of a zlib wrapper.
  35       return 31;
  36     default:
  37       MOZ_ASSERT_UNREACHABLE("Unknown compression format");
  38       return 0;
  39   }
  40 }
  41
  42 enum ZLibFlush : uint8_t { No = Z_NO_FLUSH, Yes = Z_FINISH };
  43
  44 }  // namespace mozilla::dom
  45
  46 #endif  // DOM_ZLIBHELPER_H_