Add some "unchecked" blocks

Try to identify places where integer overflow is expected and mark them as "unchecked"

src/LibHac/Common/Keys/ExternalKeyReader.cs

@@ -566,7 +566,7 @@ public static class ExternalKeyReader
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static bool IsValidNameChar(char c)
     {
-        return (c | 0x20u) - 'a' <= 'z' - 'a' || (uint)(c - '0') <= 9 || c == '_';
+        return unchecked((c | 0x20u) - 'a' <= 'z' - 'a' || (uint)(c - '0') <= 9 || c == '_');
     }
 
     private static bool TryGetKeyInfo(out SpecificKeyInfo info, List<KeyInfo> keyList, ReadOnlySpan<char> keyName)

src/LibHac/Common/U8StringBuilder.cs

@@ -147,7 +147,7 @@ public ref struct U8StringBuilder
         // Remove possible sign extension if needed
         if (mask == 'x' || mask == 'X')
         {
-            value &= (long)mask;
+            value &= unchecked((long)mask);
         }
 
         int bytesWritten;

src/LibHac/Crypto/Impl/AesCtrModeNi.cs

@@ -31,8 +31,8 @@ public struct AesCtrModeNi
         ref Vector128<byte> inBlock = ref Unsafe.As<byte, Vector128<byte>>(ref MemoryMarshal.GetReference(input));
         ref Vector128<byte> outBlock = ref Unsafe.As<byte, Vector128<byte>>(ref MemoryMarshal.GetReference(output));
 
-        Vector128<byte> byteSwapMask = Vector128.Create((ulong)0x706050403020100, 0x8090A0B0C0D0E0F).AsByte();
+        Vector128<byte> byteSwapMask = Vector128.Create(0x706050403020100ul, 0x8090A0B0C0D0E0Ful).AsByte();
-        var inc = Vector128.Create((ulong)0, 1);
+        var inc = Vector128.Create(0ul, 1ul);
 
         Vector128<byte> iv = Iv;
         Vector128<ulong> bSwappedIv = Ssse3.Shuffle(iv, byteSwapMask).AsUInt64();

src/LibHac/Crypto/Impl/AesXtsMode.cs

@@ -154,6 +154,8 @@ public struct AesXtsMode
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static void Gf128Mul(ref Buffer16 buffer)
+    {
+        unchecked
         {
             Span<ulong> b = buffer.AsSpan<ulong>();
 
@@ -162,6 +164,7 @@ public struct AesXtsMode
             b[1] = (b[1] << 1) | (b[0] >> 63);
             b[0] = (b[0] << 1) ^ tt;
         }
+    }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static void XorBuffer(ref Buffer16 output, ref Buffer16 input1, ref Buffer16 input2)

src/LibHac/FsSrv/SaveDataFileSystemService.cs

@@ -2166,7 +2166,7 @@ internal class SaveDataFileSystemService : ISaveDataTransferCoreInterface, ISave
 
     private bool IsStaticSaveDataIdValueRange(ulong id)
     {
-        return (long)id < 0;
+        return unchecked((long)id) < 0;
     }
 
     private void ModifySaveDataExtraData(ref SaveDataExtraData currentExtraData, in SaveDataExtraData extraData,

src/LibHac/Result.cs

@@ -289,7 +289,9 @@ public readonly struct Result : IEquatable<Result>
         /// The <see cref="Result"/> representing the start of this result range.
         /// If returning a <see cref="Result"/> from a function, use <see cref="Log"/> instead.
         /// </summary>
-        public Result Value => new Result((BaseType)_value);
+        // The conversion to int won't remove the part of the value containing the description end, but that doesn't
+        // matter because the constructor for Result will take care of that.
+        public Result Value => new Result(unchecked((BaseType)_value));
 
         /// <summary>
         /// Checks if the range of this <see cref="Result.Base"/> includes the provided <see cref="Result"/>.
@@ -307,7 +309,7 @@ public readonly struct Result : IEquatable<Result>
             }
 
             return result.Module == Module &&
-                   result.Description - DescriptionRangeStart <= DescriptionRangeEnd - DescriptionRangeStart;
+                   unchecked(result.Description - DescriptionRangeStart <= DescriptionRangeEnd - DescriptionRangeStart);
         }
 
         /// <summary>
@@ -356,7 +358,7 @@ public readonly struct Result : IEquatable<Result>
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static BaseType GetBitsValueLong(ulong value, int bitsOffset, int bitsCount)
         {
-            return (BaseType)(value >> bitsOffset) & ~(~default(BaseType) << bitsCount);
+            return unchecked((BaseType)(value >> bitsOffset)) & ~(~default(BaseType) << bitsCount);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -391,7 +393,7 @@ public readonly struct Result : IEquatable<Result>
             public BaseType DescriptionRangeStart => GetBitsValueLong(_value, DescriptionBitsOffset, DescriptionBitsCount);
             public BaseType DescriptionRangeEnd => GetBitsValueLong(_value, DescriptionEndBitsOffset, DescriptionBitsCount);
 
-            private Result Value => new Result((BaseType)_value);
+            private Result Value => new Result(unchecked((BaseType)_value));
 
             /// <summary>
             /// Checks if the range of this <see cref="Result.Base"/> includes the provided <see cref="Result"/>.
@@ -409,7 +411,7 @@ public readonly struct Result : IEquatable<Result>
                 }
 
                 return result.Module == Module &&
-                       result.Description - DescriptionRangeStart <= DescriptionRangeEnd - DescriptionRangeStart;
+                       unchecked(result.Description - DescriptionRangeStart <= DescriptionRangeEnd - DescriptionRangeStart);
             }
         }
     }

src/LibHac/Tools/FsSystem/Aes128XtsTransform.cs

@@ -174,7 +174,7 @@ public class Aes128XtsTransform
 
         for (int i = 2; i < bufL.Length; i += 2)
         {
-            ulong tt = (ulong)((long)a >> 63) & 0x87;
+            ulong tt = unchecked((ulong)((long)a >> 63) & 0x87);
 
             a = (a << 1) | (b >> 63);
             b = (b << 1) ^ tt;
@@ -193,7 +193,7 @@ public class Aes128XtsTransform
     {
         for (int i = 0xF; i >= 0; i--)
         {
-            value[i] = (byte)sector;
+            value[i] = unchecked((byte)sector);
             sector >>= 8;
         }
     }

src/LibHac/Util/Impl/HexConverter.cs

@@ -63,6 +63,8 @@ internal static class HexConverter
     // furthest access).
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void ToBytesBuffer(byte value, Span<byte> buffer, int startingIndex = 0, Casing casing = Casing.Upper)
+    {
+        unchecked
         {
             uint difference = ((value & 0xF0U) << 4) + (value & 0x0FU) - 0x8989U;
             uint packedResult = ((((uint)(-(int)difference) & 0x7070U) >> 4) + difference + 0xB9B9U) | (uint)casing;
@@ -70,9 +72,12 @@ internal static class HexConverter
             buffer[startingIndex + 1] = (byte)packedResult;
             buffer[startingIndex] = (byte)(packedResult >> 8);
         }
+    }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static void ToCharsBuffer(byte value, Span<char> buffer, int startingIndex = 0, Casing casing = Casing.Upper)
+    {
+        unchecked
         {
             uint difference = ((value & 0xF0U) << 4) + (value & 0x0FU) - 0x8989U;
             uint packedResult = ((((uint)(-(int)difference) & 0x7070U) >> 4) + difference + 0xB9B9U) | (uint)casing;
@@ -80,6 +85,7 @@ internal static class HexConverter
             buffer[startingIndex + 1] = (char)(packedResult & 0xFF);
             buffer[startingIndex] = (char)(packedResult >> 8);
         }
+    }
 
     public static void EncodeToUtf16(ReadOnlySpan<byte> bytes, Span<char> chars, Casing casing = Casing.Upper)
     {
@@ -181,6 +187,8 @@ internal static class HexConverter
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static int FromLowerChar(int c)
+    {
+        unchecked
         {
             if ((uint)(c - '0') <= '9' - '0')
                 return c - '0';
@@ -190,6 +198,7 @@ internal static class HexConverter
 
             return 0xFF;
         }
+    }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static bool IsHexChar(int c)
@@ -200,13 +209,13 @@ internal static class HexConverter
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static bool IsHexUpperChar(int c)
     {
-        return (uint)(c - '0') <= 9 || (uint)(c - 'A') <= ('F' - 'A');
+        return unchecked((uint)(c - '0') <= 9 || (uint)(c - 'A') <= ('F' - 'A'));
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static bool IsHexLowerChar(int c)
     {
-        return (uint)(c - '0') <= 9 || (uint)(c - 'a') <= ('f' - 'a');
+        return unchecked((uint)(c - '0') <= 9 || (uint)(c - 'a') <= ('f' - 'a'));
     }
 
     /// <summary>Map from an ASCII char to its hex value, e.g. arr['b'] == 11. 0xFF means it's not a hex digit.</summary>

src/LibHac/Util/StringUtils.cs

@@ -159,7 +159,7 @@ public static class StringUtils
 
     private static byte ToLowerAsciiInvariant(byte c)
     {
-        if ((uint)(c - 'A') <= 'Z' - 'A')
+        if (unchecked((uint)(c - 'A') <= 'Z' - 'A'))
         {
             c = (byte)(c | 0x20);
         }
@@ -240,12 +240,12 @@ public static class StringUtils
 
     public static bool IsAlpha(byte c)
     {
-        return (c | 0x20u) - (byte)'a' <= 'z' - 'a';
+        return unchecked((c | 0x20u) - (byte)'a' <= 'z' - 'a');
     }
 
     public static bool IsDigit(byte c)
     {
-        return (uint)(c - (byte)'0') <= 9;
+        return unchecked((uint)(c - (byte)'0') <= 9);
     }
 
     public static bool IsHexDigit(byte c)