Implement native layout-3 save restoration
This commit is contained in:
gamer147
294
engine/Age.Engine/Persistence/NativeNumberedSaveCodec.cs
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294
engine/Age.Engine/Persistence/NativeNumberedSaveCodec.cs
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using System.Buffers.Binary;
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using System.Text;
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namespace Age.Engine.Persistence;
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public sealed record NativeSavedScriptFrame(
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int ParentContext,
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uint ScriptId,
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IReadOnlyList<int> ReturnIndices,
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int ResumeIndex,
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int CallTargetIndex);
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public sealed record NativeSavedGfxObject(long Handle, byte[] Record);
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public sealed record NativeNumberedSaveState(
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int SavedFrameOwner,
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int EngineState,
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IReadOnlyList<int> StateWords,
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byte[] ResourceRecords,
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byte[] SurfaceRecords,
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IReadOnlyList<NativeSavedScriptFrame> Frames,
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IReadOnlyList<int> IntegerGlobals,
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IReadOnlyList<int> FloatGlobals,
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IReadOnlyList<string> StringGlobals,
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IReadOnlyList<int> PointerGlobals,
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IReadOnlyList<int> PointerStrings,
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IReadOnlyList<int> LocalPointerScratch,
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IReadOnlyList<NativeSavedGfxObject> GfxObjects,
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long RangeTransformFirst,
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int RangeTransformCount,
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byte[] RangeTransformRecord)
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{
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public const int StateWordCount = 10;
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public const int ResourceRecordsSize = 300 * 4;
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public const int SurfaceRecordsSize = 20_000;
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public const int GfxRecordSize = 0x2d4;
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}
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/// <summary>AGE SaveVersion1=3 numbered-save logical payload.</summary>
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public static class NativeNumberedSaveCodec
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{
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private const int FixedPrefixSize = 0x5304;
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private const int FrameSize = 0x414;
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private const int FixedSuffixSize = 0x414;
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private const int FrameReturnCapacity = 256;
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private const int GfxAllocationDwords = 0x2d8;
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private const int GfxConstantDwords = 0x2e1;
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private static readonly Encoding NativeEncoding = CreateNativeEncoding();
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public static byte[] Encode(NativeNumberedSaveState state)
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{
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ArgumentNullException.ThrowIfNull(state);
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ValidateState(state);
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int cutoff = state.Frames.Count - 1;
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byte[] strings = EncodeStrings(state.StringGlobals);
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int stringDwords = strings.Length / 4;
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int bankDwords = checked(
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state.IntegerGlobals.Count + state.FloatGlobals.Count + state.StringGlobals.Count
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+ state.PointerGlobals.Count + state.PointerStrings.Count + state.LocalPointerScratch.Count);
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int totalDwords = checked(
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cutoff * 0x105 + 0x53ea + bankDwords + stringDwords
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+ GfxConstantDwords + state.GfxObjects.Count * GfxAllocationDwords);
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byte[] payload = new byte[checked((totalDwords - 2) * 4)];
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WriteInt(payload, 0, cutoff);
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WriteInt(payload, 4, state.SavedFrameOwner);
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WriteInt(payload, 8, state.EngineState);
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WriteIntList(payload, 0x0c, state.StateWords);
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state.ResourceRecords.CopyTo(payload, 0x34);
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state.SurfaceRecords.CopyTo(payload, 0x4e4);
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for (int i = 0; i < state.Frames.Count; i++)
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WriteFrame(payload, FixedPrefixSize + i * FrameSize, state.Frames[i], i == cutoff);
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int at = checked(0x5718 + cutoff * FrameSize);
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int[] counts =
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[
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state.IntegerGlobals.Count, state.FloatGlobals.Count, state.StringGlobals.Count,
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state.PointerGlobals.Count, state.PointerStrings.Count, state.LocalPointerScratch.Count,
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];
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WriteIntList(payload, at, counts);
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at += 24;
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WriteIntList(payload, at, state.IntegerGlobals);
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at += state.IntegerGlobals.Count * 4;
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WriteIntList(payload, at, state.FloatGlobals);
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at += state.FloatGlobals.Count * 4;
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WriteInt(payload, at, stringDwords);
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at += 4;
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strings.CopyTo(payload, at);
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at += strings.Length;
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WriteIntList(payload, at, state.PointerGlobals);
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at += state.PointerGlobals.Count * 4;
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WriteIntList(payload, at, state.PointerStrings);
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at += state.PointerStrings.Count * 4;
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WriteIntList(payload, at, state.LocalPointerScratch);
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at += state.LocalPointerScratch.Count * 4;
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WriteInt(payload, at, NativeNumberedSaveState.GfxRecordSize);
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WriteInt(payload, at + 4, state.GfxObjects.Count);
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at += 8;
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foreach (NativeSavedGfxObject gfx in state.GfxObjects)
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{
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WriteInt(payload, at, unchecked((int)gfx.Handle));
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gfx.Record.CopyTo(payload, at + 4);
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at += 4 + NativeNumberedSaveState.GfxRecordSize;
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}
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WriteInt(payload, at, unchecked((int)state.RangeTransformFirst));
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WriteInt(payload, at + 4, state.RangeTransformCount);
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state.RangeTransformRecord.CopyTo(payload, at + 8);
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return payload;
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}
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public static NativeNumberedSaveState Decode(ReadOnlySpan<byte> payload)
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{
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if (payload.Length < 0x5718)
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throw new InvalidDataException("Numbered-save layout 3 payload is truncated.");
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int cutoff = ReadNonNegative(payload, 0, "saved frame cutoff");
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int fixedBytes = checked(0x5718 + cutoff * FrameSize);
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Require(payload, 0, fixedBytes, "numbered-save fixed state");
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int[] stateWords = ReadInts(payload, 0x0c, NativeNumberedSaveState.StateWordCount);
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byte[] resources = payload.Slice(0x34, NativeNumberedSaveState.ResourceRecordsSize).ToArray();
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byte[] surfaces = payload.Slice(0x4e4, NativeNumberedSaveState.SurfaceRecordsSize).ToArray();
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var frames = new NativeSavedScriptFrame[cutoff + 1];
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for (int i = 0; i < frames.Length; i++)
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frames[i] = ReadFrame(payload, FixedPrefixSize + i * FrameSize);
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int at = fixedBytes;
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int[] counts = ReadInts(payload, at, 6);
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if (counts.Any(count => count < 0))
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throw new InvalidDataException("Numbered-save layout 3 contains a negative bank count.");
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at += 24;
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int[] integers = ReadInts(payload, at, counts[0]);
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at = checked(at + counts[0] * 4);
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int[] floats = ReadInts(payload, at, counts[1]);
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at = checked(at + counts[1] * 4);
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int stringDwords = ReadNonNegative(payload, at, "string blob length");
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at += 4;
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int stringBytes = checked(stringDwords * 4);
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Require(payload, at, stringBytes, "numbered-save string blob");
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string[] strings = DecodeStrings(payload.Slice(at, stringBytes), counts[2]);
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at += stringBytes;
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int[] pointers = ReadInts(payload, at, counts[3]);
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at = checked(at + counts[3] * 4);
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int[] pointerStrings = ReadInts(payload, at, counts[4]);
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at = checked(at + counts[4] * 4);
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int[] localPointerScratch = ReadInts(payload, at, counts[5]);
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at = checked(at + counts[5] * 4);
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int gfxRecordSize = ReadNonNegative(payload, at, "gfx record size");
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int gfxCount = ReadNonNegative(payload, at + 4, "gfx object count");
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if (gfxRecordSize != NativeNumberedSaveState.GfxRecordSize)
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throw new InvalidDataException($"Unsupported native gfx record size 0x{gfxRecordSize:x}.");
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at += 8;
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var objects = new NativeSavedGfxObject[gfxCount];
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for (int i = 0; i < objects.Length; i++)
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{
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Require(payload, at, 4 + gfxRecordSize, "numbered-save gfx object");
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long handle = ReadInt(payload, at);
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objects[i] = new NativeSavedGfxObject(handle, payload.Slice(at + 4, gfxRecordSize).ToArray());
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at += 4 + gfxRecordSize;
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}
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Require(payload, at, 8 + gfxRecordSize, "numbered-save range transform");
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long rangeFirst = ReadInt(payload, at);
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int rangeCount = ReadInt(payload, at + 4);
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byte[] rangeRecord = payload.Slice(at + 8, gfxRecordSize).ToArray();
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return new NativeNumberedSaveState(
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ReadInt(payload, 4), ReadInt(payload, 8), stateWords, resources, surfaces, frames,
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integers, floats, strings, pointers, pointerStrings, localPointerScratch, objects,
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rangeFirst, rangeCount, rangeRecord);
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}
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public static NativeNumberedSaveState Empty(IReadOnlyList<NativeSavedScriptFrame> frames)
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=> new(
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0, 0, new int[NativeNumberedSaveState.StateWordCount],
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new byte[NativeNumberedSaveState.ResourceRecordsSize],
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new byte[NativeNumberedSaveState.SurfaceRecordsSize],
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frames, Array.Empty<int>(), Array.Empty<int>(), Array.Empty<string>(),
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Array.Empty<int>(), Array.Empty<int>(), Array.Empty<int>(),
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Array.Empty<NativeSavedGfxObject>(), 0, 0,
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new byte[NativeNumberedSaveState.GfxRecordSize]);
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private static void WriteFrame(Span<byte> payload, int offset, NativeSavedScriptFrame frame, bool terminal)
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{
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if (frame.ReturnIndices.Count > FrameReturnCapacity)
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throw new InvalidDataException("A native saved frame cannot hold more than 256 return entries.");
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WriteInt(payload, offset, frame.ParentContext);
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WriteInt(payload, offset + 4, unchecked((int)frame.ScriptId));
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WriteInt(payload, offset + 8, frame.ReturnIndices.Count);
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for (int i = 0; i < frame.ReturnIndices.Count; i++)
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WriteInt(payload, offset + 12 + i * 4, frame.ReturnIndices[i]);
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WriteInt(payload, offset + 0x40c, frame.ResumeIndex);
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WriteInt(payload, offset + 0x410, terminal ? -1 : frame.CallTargetIndex);
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}
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private static NativeSavedScriptFrame ReadFrame(ReadOnlySpan<byte> payload, int offset)
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{
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int count = ReadNonNegative(payload, offset + 8, "frame return count");
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if (count > FrameReturnCapacity)
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throw new InvalidDataException("Numbered-save frame return count exceeds 256.");
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return new NativeSavedScriptFrame(
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ReadInt(payload, offset), unchecked((uint)ReadInt(payload, offset + 4)),
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ReadInts(payload, offset + 12, count),
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ReadInt(payload, offset + 0x40c), ReadInt(payload, offset + 0x410));
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}
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private static byte[] EncodeStrings(IReadOnlyList<string> strings)
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{
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using var stream = new MemoryStream();
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foreach (string text in strings)
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{
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byte[] encoded = NativeEncoding.GetBytes(text ?? "");
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stream.Write(encoded);
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stream.WriteByte(0);
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}
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while ((stream.Length & 3) != 0) stream.WriteByte(0);
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return stream.ToArray();
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}
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private static string[] DecodeStrings(ReadOnlySpan<byte> blob, int count)
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{
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var result = new string[count];
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int at = 0;
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for (int i = 0; i < count; i++)
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{
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if (at >= blob.Length)
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throw new InvalidDataException("Numbered-save string blob ended before its declared string count.");
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int end = blob[at..].IndexOf((byte)0);
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if (end < 0)
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throw new InvalidDataException("Numbered-save string blob ended before its declared string count.");
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result[i] = NativeEncoding.GetString(blob.Slice(at, end));
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at += end + 1;
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}
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return result;
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}
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private static void ValidateState(NativeNumberedSaveState state)
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{
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if (state.Frames.Count == 0) throw new InvalidDataException("A numbered save requires at least one frame.");
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if (state.StateWords.Count != NativeNumberedSaveState.StateWordCount)
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throw new InvalidDataException("Numbered-save state word count must be 10.");
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if (state.ResourceRecords.Length != NativeNumberedSaveState.ResourceRecordsSize)
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throw new InvalidDataException("Numbered-save resource table must be 1,200 bytes.");
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if (state.SurfaceRecords.Length != NativeNumberedSaveState.SurfaceRecordsSize)
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throw new InvalidDataException("Numbered-save surface table must be 20,000 bytes.");
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if (state.RangeTransformRecord.Length != NativeNumberedSaveState.GfxRecordSize
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|| state.GfxObjects.Any(item => item.Record.Length != NativeNumberedSaveState.GfxRecordSize))
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throw new InvalidDataException("Numbered-save gfx records must be 0x2d4 bytes.");
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}
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private static int[] ReadInts(ReadOnlySpan<byte> source, int offset, int count)
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{
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int bytes = checked(count * 4);
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Require(source, offset, bytes, "numbered-save integer array");
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var values = new int[count];
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for (int i = 0; i < count; i++) values[i] = ReadInt(source, offset + i * 4);
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return values;
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}
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private static void WriteIntList(Span<byte> destination, int offset, IReadOnlyList<int> values)
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{
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for (int i = 0; i < values.Count; i++) WriteInt(destination, offset + i * 4, values[i]);
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}
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private static int ReadNonNegative(ReadOnlySpan<byte> source, int offset, string name)
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{
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int value = ReadInt(source, offset);
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if (value < 0) throw new InvalidDataException($"Numbered-save {name} is negative.");
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return value;
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}
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private static int ReadInt(ReadOnlySpan<byte> source, int offset)
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{
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Require(source, offset, 4, "numbered-save dword");
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return BinaryPrimitives.ReadInt32LittleEndian(source.Slice(offset, 4));
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}
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private static void WriteInt(Span<byte> destination, int offset, int value)
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=> BinaryPrimitives.WriteInt32LittleEndian(destination.Slice(offset, 4), value);
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private static void Require(ReadOnlySpan<byte> source, int offset, int count, string name)
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{
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if (offset < 0 || count < 0 || offset > source.Length - count)
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throw new InvalidDataException($"{name} is truncated.");
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}
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private static Encoding CreateNativeEncoding()
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{
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Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
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return Encoding.GetEncoding(932);
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}
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}
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