Clean up `NESSyncSettings.InitialWRamStatePattern`

src/BizHawk.Client.EmuHawk/config/NES/NESSyncSettingsForm.cs

@@ -49,10 +49,8 @@ namespace BizHawk.Client.EmuHawk
 			RegionComboBox.Items.AddRange(Enum.GetNames(typeof(NES.NESSyncSettings.Region)).Cast<object>().ToArray());
 			RegionComboBox.SelectedItem = Enum.GetName(typeof(NES.NESSyncSettings.Region), _syncSettings.RegionOverride);
 
-			if (_syncSettings.InitialWRamStatePattern is { Count: > 0 } initWRAMPattern)
-			{
-				RamPatternOverrideBox.Text = initWRAMPattern.BytesToHexString();
-			}
+			var initWRAMPattern = _syncSettings.InitialWRamStatePattern;
+			if (initWRAMPattern.Length is not 0) RamPatternOverrideBox.Text = initWRAMPattern.BytesToHexString();
 		}
 
 		private void CancelBtn_Click(object sender, EventArgs e)
@@ -69,14 +67,14 @@ namespace BizHawk.Client.EmuHawk
 				typeof(NES.NESSyncSettings.Region),
 				(string)RegionComboBox.SelectedItem);
 
-			var oldRam = _syncSettings.InitialWRamStatePattern ?? new List<byte>();
+			var oldRam = _syncSettings.InitialWRamStatePattern;
 
 			if (!string.IsNullOrWhiteSpace(RamPatternOverrideBox.Text))
 			{
 				_syncSettings.InitialWRamStatePattern = Enumerable.Range(0, RamPatternOverrideBox.Text.Length)
 					.Where(x => x % 2 == 0)
 					.Select(x => Convert.ToByte(RamPatternOverrideBox.Text.Substring(x, 2), 16))
-					.ToList();
+					.ToArray();
 			}
 			else
 			{
@@ -85,7 +83,7 @@ namespace BizHawk.Client.EmuHawk
 
 			bool changed = (_dataTableDictionary != null && _dataTableDictionary.WasModified) ||
 				old != _syncSettings.RegionOverride ||
-				!(oldRam.SequenceEqual(_syncSettings.InitialWRamStatePattern ?? new List<byte>()));
+				!oldRam.SequenceEqual(_syncSettings.InitialWRamStatePattern);
 
 			DialogResult = DialogResult.OK;
 			if (changed)

src/BizHawk.Emulation.Common/U8ArrayAsNormalJSONListConverter.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+
+namespace BizHawk.Emulation.Common
+{
+	/// <remarks>seems unnecessary, but suggested by <see href="https://www.newtonsoft.com/json/help/html/Performance.htm#JsonConverters">official docs</see> so sure why not</remarks>
+	public sealed class U8ArrayAsNormalJSONListResolver : DefaultContractResolver
+	{
+		public static readonly U8ArrayAsNormalJSONListResolver INSTANCE = new();
+
+		protected override JsonContract CreateContract(Type objectType)
+		{
+			var contract = base.CreateContract(objectType);
+			if (objectType == typeof(byte[])) contract.Converter = U8ArrayAsNormalJSONListConverter.INSTANCE;
+			return contract;
+		}
+	}
+
+	/// <remarks>based on <see href="https://stackoverflow.com/a/15228384">this SO answer</see></remarks>
+	public sealed class U8ArrayAsNormalJSONListConverter : JsonConverter<byte[]?>
+	{
+		public static readonly U8ArrayAsNormalJSONListConverter INSTANCE = new();
+
+		public override byte[]? ReadJson(JsonReader reader, Type objectType, byte[]? existingValue, bool hasExistingValue, JsonSerializer serializer)
+		{
+			if (reader.TokenType is JsonToken.Null) return null;
+			if (reader.TokenType is not JsonToken.StartArray) throw new Exception($"Unexpected token when reading bytes: expected {nameof(JsonToken.StartArray)}, got {reader.TokenType}");
+			List<byte> list = new();
+			while (reader.Read()) switch (reader.TokenType)
+			{
+				case JsonToken.Integer:
+					list.Add(reader.Value switch
+					{
+						byte b => b,
+						long l and >= byte.MinValue and <= byte.MaxValue => unchecked((byte) l),
+						var o => throw new Exception($"Integer literal outside u8 range: {o}")
+					});
+					continue;
+				case JsonToken.EndArray:
+					return list.ToArray();
+				case JsonToken.Comment:
+					continue;
+				default:
+					throw new Exception($"Unexpected token when reading bytes: {reader.TokenType}");
+			}
+			throw new Exception("Unexpected end when reading bytes");
+		}
+
+		public override void WriteJson(JsonWriter writer, byte[]? value, JsonSerializer serializer)
+		{
+			if (value is null)
+			{
+				writer.WriteNull();
+				return;
+			}
+			writer.WriteStartArray();
+			for (var i = 0; i < value.Length; i++) writer.WriteValue(value[i]);
+			writer.WriteEndArray();
+		}
+	}
+}

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.Core.cs

@@ -227,11 +227,12 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			// apu has some specific power up bahaviour that we will emulate here
 			apu.NESHardReset();
 
-			if (SyncSettings.InitialWRamStatePattern != null && SyncSettings.InitialWRamStatePattern.Any())
+			var initWRAMPattern = SyncSettings.InitialWRamStatePattern;
+			if (initWRAMPattern.Length is not 0)
 			{
 				for (int i = 0; i < 0x800; i++)
 				{
-					ram[i] = SyncSettings.InitialWRamStatePattern[i % SyncSettings.InitialWRamStatePattern.Count];
+					ram[i] = initWRAMPattern[i % initWRAMPattern.Length];
 				}
 			}
 			else

src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.ISettable.cs

@@ -1,9 +1,12 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Linq;
 
 using BizHawk.Common;
 using BizHawk.Emulation.Common;
 
+using Newtonsoft.Json;
+
 namespace BizHawk.Emulation.Cores.Nintendo.NES
 {
 	public partial class NES : ISettable<NES.NESSettings, NES.NESSyncSettings>
@@ -59,7 +62,25 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 
 			public NESControlSettings Controls = new NESControlSettings();
 
-			public List<byte> InitialWRamStatePattern = null;
+			[JsonConverter(typeof(U8ArrayAsNormalJSONListConverter))] // this preserves the old behaviour of e,g, 0x1234ABCD --> [18,52,171,205]; omitting it will use base64 e.g. "EjSrzQ=="
+			[JsonProperty(PropertyName = nameof(InitialWRamStatePattern))]
+			private byte[]/*?*/ _initialWRamStatePattern = null;
+
+			[JsonIgnore]
+			public byte[] InitialWRamStatePattern
+			{
+				get
+				{
+					if (_initialWRamStatePattern is null) return Array.Empty<byte>();
+					if (_initialWRamStatePattern.Length is 0)
+					{
+						_initialWRamStatePattern = null;
+						return Array.Empty<byte>();
+					}
+					return _initialWRamStatePattern;
+				}
+				set => _initialWRamStatePattern = value.Length is 0 ? null : value;
+			}
 
 			public NESSyncSettings Clone()
 			{
@@ -75,7 +96,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 				return !(Util.DictionaryEqual(x.BoardProperties, y.BoardProperties)
 					&& x.RegionOverride == y.RegionOverride
 					&& !NESControlSettings.NeedsReboot(x.Controls, y.Controls)
-					&& ((x.InitialWRamStatePattern ?? new List<byte>()).SequenceEqual(y.InitialWRamStatePattern ?? new List<byte>()))
+					&& x.InitialWRamStatePattern.SequenceEqual(y.InitialWRamStatePattern)
 					&& x.VSDipswitches.Equals(y.VSDipswitches));
 			}