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16d9576e42
Renames ZLibHelper.h to be CompressionStreamHelper.h and attempts to make shared functionality between various implementations of CompressionStreamAlgorithms and DecompressionStreamAlgorithms as easily shared as possible. Differential Revision: https://phabricator.services.mozilla.com/D239148
64 lines
2.1 KiB
C++
64 lines
2.1 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef DOM_COMPRESSION_STREAM_HELPER_H_
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#define DOM_COMPRESSION_STREAM_HELPER_H_
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#include "js/TypeDecls.h"
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#include "zlib.h"
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#include "mozilla/dom/CompressionStreamBinding.h"
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namespace mozilla::dom::compression {
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// A top-level, library-agnostic flush enum that should be converted
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// into the native flush values for a given (de)compression library
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// with a function defined below.
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enum class Flush : bool { No, Yes };
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inline uint8_t intoZLibFlush(Flush aFlush) {
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switch (aFlush) {
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case Flush::No: {
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return Z_NO_FLUSH;
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}
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case Flush::Yes: {
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return Z_FINISH;
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}
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default: {
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MOZ_ASSERT_UNREACHABLE("Unknown flush mode");
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return Z_NO_FLUSH;
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}
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}
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}
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// From the docs in
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// https://searchfox.org/mozilla-central/source/modules/zlib/src/zlib.h
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inline int8_t ZLibWindowBits(CompressionFormat format) {
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switch (format) {
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case CompressionFormat::Deflate:
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// The windowBits parameter is the base two logarithm of the window size
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// (the size of the history buffer). It should be in the range 8..15 for
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// this version of the library. Larger values of this parameter result
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// in better compression at the expense of memory usage.
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return 15;
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case CompressionFormat::Deflate_raw:
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// windowBits can also be –8..–15 for raw deflate. In this case,
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// -windowBits determines the window size.
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return -15;
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case CompressionFormat::Gzip:
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// windowBits can also be greater than 15 for optional gzip encoding.
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// Add 16 to windowBits to write a simple gzip header and trailer around
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// the compressed data instead of a zlib wrapper.
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return 31;
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default:
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MOZ_ASSERT_UNREACHABLE("Unknown compression format");
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return 0;
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}
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}
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} // namespace mozilla::dom::compression
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#endif // DOM_COMPRESSION_STREAM_HELPER_H_
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