Android and ARM processors

ARM processor is a 32-bit reduced-instruction set processor architecture that is widely used in many embedded system designs. It contains the following three instruction types: ARM instruction, Thumb instruction, and Thumb2 instruction, both of which are 32-bit except that the Thumb instruction is 16-bit.

1.1 Advantages of ARM processor

The advantage of ARM processors is not in performance, but in execution efficiency. ARM processor adopts RISC pipeline instruction set, which is at a disadvantage in completing comprehensive work, but in some applications with relatively fixed tasks, the advantage can be brought into play.

In addition to high execution efficiency, ARM also has the advantages of fixed instruction length, low cost, low consumption and small size.

ARM of the structure of the data interface of the computer is through a dedicated CPU and data storage devices are connected, so the ARM processor properties, such as storage, memory expansion to (generally in the product design has set its memory and data storage capacity), so the ARM of the structure of the system, is generally not considered extension, basic pursues the principle of “good enough”.

1.2 Relationship between native programs and ARM assembly

The Android embedded intelligent operating system is based on Linux kernel, and the embedded system Linux is based on ARM platform.

Android native programs can execute programs. In the previous chapter, we learned how to write executable programs. In the process of writing, relevant configuration is carried out in two.

As you can see, the native program runs on the Linux kernel and the processor is based on ARM.

Summary:

Through the study of this lesson, I understand the advantages of ARM processor, such as high execution efficiency, low consumption and embedded development, and I also know that only when the task is relatively fixed can the ARM processor give full play to its maximum advantages. Finally, we also learned the relationship between Android and ARM: Android is based on Linux kernel, using ARM processor.