Nios II定制指令用户指南：With the Altera Nios II embedded processor, you as the system designer can accelerate time-critical software algorithms by adding custom instructions to the Nios II processor instruction set. Using custominstructions, you can reduce a complex sequence of standard instructions to a single instruction implemented in hardware. You can use this feature for a variety of applications, for example, to optimize software innerloops for digital signal processing (DSP), packet header processing, and computation-intensive applications. The Nios II configuration wizard,part of the Quartus® II software’s SOPC Builder, provides a graphical user interface (GUI) used to add up to 256 custom instructions to the Nios II processor.The custom instruction logic connects directly to the Nios II arithmetic logic unit (ALU) as shown in Figure 1–1.