LibAudio+LibRIFF: Move general RIFF handling to LibRIFF

This splits the RIFFTypes header/TU into the WAV specific parts, which
move to WavTypes.h, as well as the general RIFF parts which move to the
new LibRIFF.

Sidenote for the spec comments: even though they are linked from a site
that explains the WAV format, the document is the (an) overall RIFF spec
from Microsoft. A better source may be used later; the changes to the
header are as minimal as possible.

Userland/Libraries/LibRIFF/CMakeLists.txt

@@ -0,0 +1,6 @@
+set(SOURCES
+    Types.cpp
+)
+
+serenity_lib(LibRIFF riff)
+target_link_libraries(LibRIFF PRIVATE LibCore)

Userland/Libraries/LibRIFF/Types.cpp

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2023, kleines Filmröllchen <filmroellchen@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "Types.h"
+#include <AK/Endian.h>
+#include <AK/Stream.h>
+#include <AK/Try.h>
+#include <AK/TypeCasts.h>
+
+namespace RIFF {
+
+ErrorOr<ChunkID> ChunkID::read_from_stream(Stream& stream)
+{
+    Array<u8, chunk_id_size> id;
+    TRY(stream.read_until_filled(id.span()));
+    return ChunkID { id };
+}
+
+ErrorOr<Chunk> Chunk::read_from_stream(Stream& stream)
+{
+    auto id = TRY(stream.read_value<ChunkID>());
+
+    u32 size = TRY(stream.read_value<LittleEndian<u32>>());
+    auto data = TRY(FixedArray<u8>::create(size));
+    TRY(stream.read_until_filled(data.span()));
+
+    // RIFF chunks may have trailing padding to align to x86 "words" (i.e. 2 bytes).
+    if (is<SeekableStream>(stream)) {
+        if (!stream.is_eof()) {
+            auto stream_position = TRY(static_cast<SeekableStream&>(stream).tell());
+            if (stream_position % 2 != 0)
+                TRY(static_cast<SeekableStream&>(stream).seek(1, SeekMode::FromCurrentPosition));
+        }
+    } else {
+        dbgln("RIFF Warning: Cannot align stream to 2-byte boundary, next chunk may be bogus!");
+    }
+
+    return Chunk {
+        id,
+        size,
+        move(data),
+    };
+}
+
+ErrorOr<List> List::read_from_stream(Stream& stream)
+{
+    auto type = TRY(stream.read_value<ChunkID>());
+    Vector<Chunk> chunks;
+    while (!stream.is_eof())
+        TRY(chunks.try_append(TRY(stream.read_value<Chunk>())));
+
+    return List {
+        .type = type,
+        .chunks = move(chunks),
+    };
+}
+
+StringView ChunkID::as_ascii_string() const
+{
+    return StringView { id_data.span() };
+}
+
+bool ChunkID::operator==(StringView const& other_string) const
+{
+    return as_ascii_string() == other_string;
+}
+
+FixedMemoryStream Chunk::data_stream()
+{
+    return FixedMemoryStream { data.span() };
+}
+
+}

Userland/Libraries/LibRIFF/Types.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2018-2023, the SerenityOS developers.
+ * Copyright (c) 2023, kleines Filmröllchen <filmroellchen@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/FixedArray.h>
+#include <AK/Forward.h>
+#include <AK/MemoryStream.h>
+#include <AK/Types.h>
+
+namespace RIFF {
+
+static constexpr StringView const riff_magic = "RIFF"sv;
+static constexpr StringView const list_chunk_id = "LIST"sv;
+
+static constexpr size_t const chunk_id_size = 4;
+
+struct ChunkID {
+    static ErrorOr<ChunkID> read_from_stream(Stream& stream);
+    StringView as_ascii_string() const;
+    bool operator==(ChunkID const&) const = default;
+    bool operator==(StringView const&) const;
+
+    Array<u8, chunk_id_size> id_data;
+};
+
+// http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/riffmci.pdf page 11 (Chunks)
+struct Chunk {
+    static ErrorOr<Chunk> read_from_stream(Stream& stream);
+    FixedMemoryStream data_stream();
+
+    ChunkID id;
+    u32 size;
+    FixedArray<u8> data;
+};
+
+// http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Docs/riffmci.pdf page 23 (LIST type)
+struct List {
+    static ErrorOr<List> read_from_stream(Stream& stream);
+
+    ChunkID type;
+    Vector<Chunk> chunks;
+};
+
+}