/// <summary>
/// Allocates the unmanaged memory for the midi headers and buffers.
/// </summary>
private void AllocateBuffers()
{
if (this.BufferSize > 0 && this.BufferCount > 0)
{
this.memHeaders = MemoryUtil.Alloc(MemoryUtil.SizeOfMidiHeader * this.BufferCount);
this.memBuffers = MemoryUtil.Alloc(this.BufferSize * this.BufferCount);
GC.AddMemoryPressure((MemoryUtil.SizeOfMidiHeader + this.BufferSize) * this.BufferCount);
IntPtr headerMem = IntPtr.Add(this.memHeaders, 0);
IntPtr bufferMem = IntPtr.Add(this.memBuffers, 0);
for (int i = 0; i < this.BufferCount; i++)
{
var buffer = new MidiBufferStream(headerMem, bufferMem, this.BufferSize, this.StreamAccess);
try
{
this.unusedBuffers.Enqueue(buffer);
this.mapBuffers.Add(headerMem, buffer);
headerMem = IntPtr.Add(headerMem, MemoryUtil.SizeOfMidiHeader);
bufferMem = IntPtr.Add(bufferMem, this.BufferSize);
}
catch
{
buffer.Dispose();
throw;
}
}
}
}
/// <summary>
/// Reads a unsigned integer from the memory block at the <paramref name="byteOffset"/>.
/// </summary>
/// <param name="byteOffset">An offset from the start of the memory block where the writing should start.
/// Make sure the <paramref name="byteOffset"/> is properly aligned (usually 16-bits).</param>
/// <returns>Returns the value.</returns>
public uint ReadUintAt(int byteOffset)
{
Check.IfArgumentOutOfRange(byteOffset, 0, int.MaxValue, nameof(byteOffset));
var size = MemoryUtil.SizeOf(typeof(uint));
ValidateAccess(byteOffset, size);
IntPtr location = IntPtr.Add(_memory, byteOffset);
return(*(uint *)location.ToPointer());
}
/// <summary>
/// Writes a <paramref name="value"/> to the specified <paramref name="byteOffset"/>.
/// </summary>
/// <param name="byteOffset">An offset from the start of the memory block where the writing should start.
/// Make sure the <paramref name="byteOffset"/> is properly aligned (usually 16-bits).</param>
/// <param name="value">The value to write.</param>
public void WriteUintAt(int byteOffset, uint value)
{
Check.IfArgumentOutOfRange(byteOffset, 0, int.MaxValue, nameof(byteOffset));
var size = MemoryUtil.SizeOf(typeof(uint));
ValidateAccess(byteOffset, size);
IntPtr location = IntPtr.Add(_memory, byteOffset);
*(uint *)location.ToPointer() = value;
}
/// <summary>
/// Reads a unsigned integer from the memory block at the <paramref name="byteOffset"/>.
/// </summary>
/// <param name="byteOffset">An offset from the start of the memory block where the writing should start.
/// Make sure the <paramref name="byteOffset"/> is properly aligned (usually 16-bits).</param>
/// <returns>Returns the value.</returns>
public uint ReadUintAt(int byteOffset)
{
Contract.Requires(byteOffset >= 0);
var size = MemoryUtil.SizeOf(typeof(uint));
this.ValidateAccess(byteOffset, size);
IntPtr location = IntPtr.Add(this.memory, byteOffset);
return(*(uint *)location.ToPointer());
}
/// <summary>
/// Writes a <paramref name="value"/> to the specified <paramref name="byteOffset"/>.
/// </summary>
/// <param name="byteOffset">An offset from the start of the memory block where the writing should start.
/// Make sure the <paramref name="byteOffset"/> is properly aligned (usually 16-bits).</param>
/// <param name="value">The value to write.</param>
public void WriteUintAt(int byteOffset, uint value)
{
Contract.Requires(byteOffset >= 0);
var size = MemoryUtil.SizeOf(typeof(uint));
this.ValidateAccess(byteOffset, size);
IntPtr location = IntPtr.Add(this.memory, byteOffset);
*(uint *)location.ToPointer() = value;
}
/// <summary>
/// Frees the allocated memory.
/// </summary>
private void FreeBuffers()
{
if (this.memHeaders != IntPtr.Zero)
{
MemoryUtil.Free(this.memHeaders);
this.memHeaders = IntPtr.Zero;
}
if (this.memBuffers != IntPtr.Zero)
{
MemoryUtil.Free(this.memBuffers);
this.memBuffers = IntPtr.Zero;
}
var totalLength = (MemoryUtil.SizeOfMidiHeader + this.BufferSize) * this.BufferCount;
if (totalLength > 0)
{
GC.RemoveMemoryPressure(totalLength);
}
}
