The difference between embedded C and C languages ​​Analysis of similarities and differences between embedded C and C languages

The difference between embedded C and standard C is: underlying operation: embedded C directly operates the hardware, while standard C mainly interacts through the operating system interface. Memory management: Embedded C focuses on saving memory and uses dynamic allocation with caution. Library functions: Embedded C contains the necessary library functions, which are simple and efficient. Portability: Embedded C has poor portability and requires modification of the code according to the hardware platform.

Embedded C and Standard C: Blood C flows in your bones, but has different souls

Many friends ask: What is the difference between embedded C and standard C? To put it bluntly, they look like twin brothers, but have very different personalities. In this article, let’s take a look at this layer of window paper. After reading it, you will understand why in embedded development, you cannot just use standard C code.

Standard C, which is the cornerstone of C language and the ancestor of all C languages. It defines the basic syntax, data types, library functions, etc. of C language. If you have learned C, these things will be more familiar to you. But Standard C is more like an all-rounder, it can be used to write operating systems, databases, and even games. It focuses on the integrity and standardization of the language itself and has less dependence on the hardware environment.

What about embedded C? It's like the younger brother of Standard C, inheriting most of the genes of Standard C, but it's more pragmatic and closer to the hardware. It focuses on how to efficiently control hardware under limited resources. Embedded systems usually have limited resources, small memory and weak processing capabilities, so embedded C must consider these factors.

Low-level operation: This is the soul of embedded C

Standard C rarely operates hardware directly, and it mainly interacts with the hardware through the interface provided by the operating system. But in embedded systems, the operating system is often relatively simple and even has no operating system. This means that embedded C must directly deal with hardware, such as operating registers, accessing memory mapped areas, etc. This part of the operation is usually not involved in standard C.

For example, suppose you want to control the on and off of an LED light. In a standard C environment, you may implement it through a library function, while embedded C needs to directly operate the GPIO registers corresponding to the LED light.

 <code class="c">// 嵌入式C操作GPIO寄存器示例(假设) #define LED_GPIO_BASE 0x40020000 // GPIO基地址#define LED_GPIO_DATA *(volatile unsigned int *)(LED_GPIO_BASE 0x10) // GPIO数据寄存器void led_on() { LED_GPIO_DATA |= (1 </code>

This code directly manipulates memory addresses, which is uncommon and even prohibited in standard C. The volatile keyword here is very important, it tells the compiler not to optimize this variable because its value may be changed by external factors (such as hardware). Forget adding volatile , you may encounter all kinds of strange bugs, which will drive you crazy when debugging.

Memory management: the art of calculating

Embedded systems are very sensitive to memory management. Standard C has relatively loose memory management, and you can apply and release memory at will, but embedded C must be carefully calculated to minimize memory waste. Dynamic memory allocation (malloc, free) should be used with caution in embedded systems, as memory fragmentation can cause system crashes. Many times, static memory allocation is more popular.

Library functions: streamlined and efficient

Standard C has huge library functions, but embedded C usually only contains the necessary library functions to reduce code size and runtime overhead. Some standard C library functions, such as complex string processing functions, may be simplified or replaced with more efficient custom functions in embedded systems.

Portability: You cannot have both fish and bear's paw

Standard C pursues a high degree of portability, and the same code can be compiled and run on different platforms. Embedded C is relatively poor in portability due to its direct operation of hardware. You need to modify the code according to different hardware platforms, and even optimize for different processor architectures.

Summary: Brotherly love is deep, but each performs its duties

The relationship between embedded C and standard C is like the two sides of a coin. They are closely connected but each has its own emphasis. Only by understanding the differences between them can you be at ease in embedded development. Remember, embedded C is not just a grammatical fine tuning, but also a mindset change, which requires you to have a deeper understanding of the hardware and more granular control of resources. It requires you to put in more effort, but when you successfully light up that LED light, or let your embedded system run smoothly, that sense of accomplishment is unparalleled.

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