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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef DOM_COMPRESSION_STREAM_HELPER_H_
#define DOM_COMPRESSION_STREAM_HELPER_H_
#include "js/TypeDecls.h"
#include "mozilla/dom/CompressionStreamBinding.h"
#include "zlib.h"
namespace mozilla::dom::compression {
// A top-level, library-agnostic flush enum that should be converted
// into the native flush values for a given (de)compression library
// with a function defined below.
enum class Flush : bool { No, Yes };
inline uint8_t intoZLibFlush(Flush aFlush) {
switch (aFlush) {
case Flush::No: {
return Z_NO_FLUSH;
}
case Flush::Yes: {
return Z_FINISH;
}
default: {
MOZ_ASSERT_UNREACHABLE("Unknown flush mode");
return Z_NO_FLUSH;
}
}
}
// From the docs in
// https://searchfox.org/mozilla-central/source/modules/zlib/src/zlib.h
inline int8_t ZLibWindowBits(CompressionFormat format) {
switch (format) {
case CompressionFormat::Deflate:
// The windowBits parameter is the base two logarithm of the window size
// (the size of the history buffer). It should be in the range 8..15 for
// this version of the library. Larger values of this parameter result
// in better compression at the expense of memory usage.
return 15;
case CompressionFormat::Deflate_raw:
// windowBits can also be –8..–15 for raw deflate. In this case,
// -windowBits determines the window size.
return -15;
case CompressionFormat::Gzip:
// windowBits can also be greater than 15 for optional gzip encoding.
// Add 16 to windowBits to write a simple gzip header and trailer around
// the compressed data instead of a zlib wrapper.
return 31;
default:
MOZ_ASSERT_UNREACHABLE("Unknown compression format");
return 0;
}
}
} // namespace mozilla::dom::compression
#endif // DOM_COMPRESSION_STREAM_HELPER_H_
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