From 63433e38ecca4b4b4f8ba5602f7a0fa9cea7891d Mon Sep 17 00:00:00 2001
From: Marcel Koester <m4rs@m4rs.net>
Date: Thu, 2 Mar 2023 18:35:15 +0100
Subject: [PATCH] Added new VelocityMemoryBuffer to represent memory buffers in
 Velocity land.

---
 .../Runtime/Velocity/VelocityMemoryBuffer.cs  | 152 ++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 Src/ILGPU/Runtime/Velocity/VelocityMemoryBuffer.cs

diff --git a/Src/ILGPU/Runtime/Velocity/VelocityMemoryBuffer.cs b/Src/ILGPU/Runtime/Velocity/VelocityMemoryBuffer.cs
new file mode 100644
index 000000000..e82ae0aaa
--- /dev/null
+++ b/Src/ILGPU/Runtime/Velocity/VelocityMemoryBuffer.cs
@@ -0,0 +1,152 @@
+// ---------------------------------------------------------------------------------------
+//                                        ILGPU
+//                        Copyright (c) 2022-2023 ILGPU Project
+//                                    www.ilgpu.net
+//
+// File: VelocityMemoryBuffer.cs
+//
+// This file is part of ILGPU and is distributed under the University of Illinois Open
+// Source License. See LICENSE.txt for details.
+// ---------------------------------------------------------------------------------------
+
+using ILGPU.Runtime.CPU;
+using ILGPU.Util;
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+namespace ILGPU.Runtime.Velocity
+{
+    /// <summary>
+    /// A memory buffer that lives in CPU space.
+    /// </summary>
+    public class VelocityMemoryBuffer : MemoryBuffer
+    {
+        #region Instance
+
+        /// <summary>
+        /// Initializes this array view source on the CPU.
+        /// </summary>
+        /// <param name="accelerator">The parent accelerator (if any).</param>
+        /// <param name="length">The length of this source.</param>
+        /// <param name="elementSize">The element size.</param>
+        internal VelocityMemoryBuffer(
+            Accelerator accelerator,
+            long length,
+            int elementSize)
+            : base(accelerator, length, elementSize)
+        {
+            // Ensure that all element accesses will be properly aligned
+            long nativeLength = length * elementSize;
+            int alignmentOffset = Interop.ComputeAlignmentOffset(
+                nativeLength,
+                elementSize * accelerator.WarpSize);
+            // Pad the length to ensure a valid buffer size
+            long paddedLength = nativeLength + alignmentOffset;
+
+            // Allocate resources and assign pointers
+            NativeBufferPtr = Marshal.AllocHGlobal(new IntPtr(paddedLength));
+            NativePtr = NativeBufferPtr + alignmentOffset;
+        }
+
+        #endregion
+
+        #region Properties
+
+        /// <summary>
+        /// Returns the natively allocated underlying buffer pointer which may not be
+        /// aligned in all cases.
+        /// </summary>
+        public IntPtr NativeBufferPtr { get; private set; }
+
+        #endregion
+
+        #region Methods
+
+        /// <inheritdoc/>
+        protected internal override void MemSet(
+            AcceleratorStream stream,
+            byte value,
+            in ArrayView<byte> targetView) =>
+            CPUMemoryBuffer.CPUMemSet(
+                targetView.LoadEffectiveAddressAsPtr(),
+                value,
+                0L,
+                targetView.LengthInBytes);
+
+        /// <inheritdoc/>
+        protected internal override void CopyFrom(
+            AcceleratorStream stream,
+            in ArrayView<byte> sourceView,
+            in ArrayView<byte> targetView) =>
+            CPUMemoryBuffer.CPUCopyFrom(stream, sourceView, targetView);
+
+        /// <inheritdoc/>
+        protected internal override void CopyTo(
+            AcceleratorStream stream,
+            in ArrayView<byte> sourceView,
+            in ArrayView<byte> targetView) =>
+            CPUMemoryBuffer.CPUCopyTo(stream, sourceView, targetView);
+
+        #endregion
+
+        #region IDisposable
+
+        /// <summary>
+        /// Disposes the underlying memory buffer.
+        /// </summary>
+        protected override void DisposeAcceleratorObject(bool disposing)
+        {
+            Marshal.FreeHGlobal(NativeBufferPtr);
+            NativeBufferPtr = IntPtr.Zero;
+            NativePtr = IntPtr.Zero;
+        }
+
+        #endregion
+
+    }
+
+    sealed class VelocityMemoryBufferPool : VelocityMemoryBuffer
+    {
+        #region Instance
+
+        private int sharedMemoryOffset;
+
+        public VelocityMemoryBufferPool(
+            VelocityAccelerator accelerator,
+            int size)
+            : base(accelerator, size, 1)
+        { }
+
+        #endregion
+
+        #region Methods
+
+        /// <summary>
+        /// Resets the internal shared memory offset.
+        /// </summary>
+        public void Reset() => sharedMemoryOffset = 0;
+
+        /// <summary>
+        /// Gets a chunk of memory of a certain type.
+        /// </summary>
+        /// <param name="length">The number of elements.</param>
+        /// <typeparam name="T">The element type to allocate.</typeparam>
+        /// <returns>A view pointing to the right chunk of shared memory.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public ArrayView<T> Allocate<T>(int length)
+            where T : unmanaged
+        {
+            int totalElementSize = length * Interop.SizeOf<T>();
+            int alignment = Interop.ComputeAlignmentOffset(
+                sharedMemoryOffset,
+                totalElementSize);
+            int newOffset = sharedMemoryOffset + alignment;
+            sharedMemoryOffset += alignment + totalElementSize;
+            return new ArrayView<T>(this, newOffset, length);
+        }
+
+        #endregion
+    }
+}