From 29ad1980033061704d1fe1e86ff13e1ff6e3d988 Mon Sep 17 00:00:00 2001
From: Jim Horvath <38920027+jhorv@users.noreply.github.com>
Date: Sun, 4 Feb 2024 01:09:19 -0500
Subject: [PATCH] - WritableRegion: enable wrapping IMemoryOwner<byte> -
 IVirtualMemoryManager impls of GetWritableRegion() use pooled memory when
 region is non-contiguous. - IVirtualMemoryManager: add GetReadOnlySequence()
 and impls - ByteMemoryPool: add new method RentCopy() - ByteMemoryPool: make
 class static, remove ctor and singleton field from earlier impl

---
 src/Ryujinx.Common/Memory/ByteMemoryPool.cs   | 14 ++++++++++
 .../Memory/BytesReadOnlySequenceSegment.cs    | 26 +++++++++++++++++++
 src/Ryujinx.Memory/IVirtualMemoryManager.cs   | 10 +++++++
 3 files changed, 50 insertions(+)
 create mode 100644 src/Ryujinx.Common/Memory/BytesReadOnlySequenceSegment.cs

diff --git a/src/Ryujinx.Common/Memory/ByteMemoryPool.cs b/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
index 6fd6a98aa7..53bbee4fa6 100644
--- a/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
+++ b/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
@@ -78,6 +78,20 @@ namespace Ryujinx.Common.Memory
 
             return buffer;
         }
+        
+        /// <summary>
+        /// Copies <paramref name="buffer"/> into a newly rented byte memory buffer.
+        /// </summary>
+        /// <param name="buffer">The byte buffer to copy</param>
+        /// <returns>A <see cref="IMemoryOwner{Byte}"/> wrapping the rented memory with <paramref name="buffer"/> copied to it</returns>
+        public static IMemoryOwner<byte> RentCopy(ReadOnlySpan<byte> buffer)
+        {
+            var copy = RentImpl(buffer.Length);
+
+            buffer.CopyTo(copy.Memory.Span);
+
+            return copy;
+        }
 
         /// <summary>
         /// Copies <paramref name="buffer"/> into a newly rented byte memory buffer.
diff --git a/src/Ryujinx.Common/Memory/BytesReadOnlySequenceSegment.cs b/src/Ryujinx.Common/Memory/BytesReadOnlySequenceSegment.cs
new file mode 100644
index 0000000000..9c4cd1ff36
--- /dev/null
+++ b/src/Ryujinx.Common/Memory/BytesReadOnlySequenceSegment.cs
@@ -0,0 +1,26 @@
+using System;
+using System.Buffers;
+
+namespace Ryujinx.Common.Memory
+{
+    /// <summary>
+    /// A concrete implementation of <seealso cref="ReadOnlySequence{T}"/>,
+    /// with methods to help build a full sequence.
+    /// </summary>
+    public sealed class BytesReadOnlySequenceSegment : ReadOnlySequenceSegment<byte>
+    {
+        public BytesReadOnlySequenceSegment(Memory<byte> memory) => Memory = memory;
+
+        public BytesReadOnlySequenceSegment Append(Memory<byte> memory)
+        {
+            var nextSegment = new BytesReadOnlySequenceSegment(memory)
+            {
+                RunningIndex = RunningIndex + Memory.Length
+            };
+
+            Next = nextSegment;
+
+            return nextSegment;
+        }
+    }
+}
diff --git a/src/Ryujinx.Memory/IVirtualMemoryManager.cs b/src/Ryujinx.Memory/IVirtualMemoryManager.cs
index 96d3e85797..a94be42f73 100644
--- a/src/Ryujinx.Memory/IVirtualMemoryManager.cs
+++ b/src/Ryujinx.Memory/IVirtualMemoryManager.cs
@@ -123,6 +123,16 @@ namespace Ryujinx.Memory
                 writableRegion.Memory.Span.Fill(value);
             }
         }
+        
+        /// <summary>
+        /// Gets a read-only sequence of read-only memory blocks from CPU mapped memory.
+        /// </summary>
+        /// <param name="va">Virtual address of the data</param>
+        /// <param name="size">Size of the data</param>
+        /// <param name="tracked">True if read tracking is triggered on the memory</param>
+        /// <returns>A read-only sequence of read-only memory of the data</returns>
+        /// <exception cref="InvalidMemoryRegionException">Throw for unhandled invalid or unmapped memory accesses</exception>
+        ReadOnlySequence<byte> GetReadOnlySequence(ulong va, int size, bool tracked = false);
 
         /// <summary>
         /// Gets a read-only sequence of read-only memory blocks from CPU mapped memory.