Cpblk Field
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OpCodes.Cpblk Field


Copies a specified number bytes from a source address to a destination address.

Namespace:   System.Reflection.Emit
Assembly:  mscorlib (in mscorlib.dll)

public static readonly OpCode Cpblk

The following table lists the instruction's hexadecimal and Microsoft Intermediate Language (MSIL) assembly format, along with a brief reference summary:


Assembly Format


FE 17


Copy data from one memory block to another.

The stack transitional behavior, in sequential order, is:

  1. The destination address is pushed onto the stack.

  2. The source address is pushed onto the stack.

  3. The number of bytes to copy is pushed onto the stack.

  4. The number of bytes, the source address, and the destination address are popped from the stack; the specified number of bytes are copied from the source address to the destination address.

The cpblk instruction copies a number (type unsigned int32) of bytes from a source address (of type *, native int, or &) to a destination address (of type *, native int, or &). The behavior of cpblk is unspecified if the source and destination areas overlap.

cpblk assumes that both the source and destination addressed are aligned to the natural size of the machine. The cpblk instruction can be immediately preceded by the unaligned.<prefix> instruction to indicate that either the source or the destination is unaligned.

The operation of the cpblk instruction can be altered by an immediately preceding Volatile or Unalignedprefix instruction.

NullReferenceException may be thrown if an invalid address is detected.

The following Emit method overload can use the cpblk opcode:

  • ILGenerator.Emit(OpCode)

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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