VxWorks 7编程指南：全面详解与授权信息

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VxWorks 7 Programmer's Guide 是一份详细的文档，专为VxWorks 7的程序员设计，这是由Wind River Systems公司开发的一款嵌入式实时操作系统。该指南提供了深入的编程指导，涵盖了VxWorks的核心功能、系统架构、API使用、以及开发流程的相关细节。 VxWorks 7作为一款商业级的操作系统，注重实时性和可靠性，适用于严苛的工业控制、航空航天、汽车电子等领域的应用。版权信息表明，所有内容受2019年Wind River Systems公司版权保护，未经许可禁止任何形式的复制或传播。该手册的核心内容包括： 1. **系统概述**：介绍了VxWorks 7的基本架构和特性，如微内核设计、实时性保证、内存管理和任务调度。 2. **API参考**：详细列出了VxWorks提供的核心服务接口，如文件系统、网络通信、设备驱动程序接口，以及用于创建和管理任务、队列和中断处理的函数。 3. **编程技巧与最佳实践**：针对不同应用场景，提供了代码编写规范、内存优化策略和错误处理建议，帮助开发者编写高效、稳定的代码。 4. **安装与配置**：指南中可能包含第三方软件的集成说明和 Wind River Share (WindShare) 的链接，这些资源可以帮助用户了解如何下载、安装和配置所需的软件组件。 5. **安全与认证**：讨论了VxWorks的安全特性和合规性要求，包括硬件抽象层(HAL)安全策略和满足特定行业的安全标准。 6. **示例与调试**：为了便于理解，手册还可能包含实用的示例代码和调试工具的使用教程，以便开发者在遇到问题时能快速定位和解决问题。 7. **版权和商标**：最后部分强调了Wind River Systems及其合作伙伴的商标政策，并提示读者查阅公司网站获取关于商标使用的进一步信息。 VxWorks 7 Programmer's Guide 是一个宝贵的资源库，为VxWorks 7的开发人员提供了全面的技术支持，无论是初次接触该系统的开发者还是经验丰富的老手，都能从中受益匪浅。通过深入学习和实践，开发者可以更好地利用VxWorks构建高性能、可信赖的实时应用。

Some header files mark internal details using HIDDEN comments:

/* HIDDEN */

...

/* END HIDDEN */

Internal details are also hidden with private header files, which are located in directories named

private. The names of the private header files have the same root as the public ones, but with a P

added. For example, the private header file for semLib is semLibP.h.

Header Files and extern "C" Statements

Do not include system header files within extern "C" statement brackets. All VxWorks system

header files are already configured for use with C and C++ compilers. You may invalidate

declarations in the VxWorks headers if you force a C linkage on the entire header file's content.

The following is incorrect:

#ifdef _cplusplus

extern "C" {

#endif

#include <stdio.h>

But the following is correct:

#include <stdio.h>

#ifdef _cplusplus

extern "C" {

#endif

In addition, do not include a VxWorks header file within an extern "C" statement in C++ files.

The following is incorrect:

extern "C" {

#include <stdio.h>

}

But this example is correct:

#include <stdio.h>

Static Instantiation of Kernel Objects

VxWorks kernel objects, such as tasks and semaphores, can be instantiated statically as well as

dynamically. Static instantiation provides advantages in terms of performance and determinism.

Special VxWorks C macros are provided for static instantiation.

Static instantiation of a kernel object means that the object is declared as a compile-time variable

(using a special VxWorks macro), which is usually global in scope. The compiler therefore

allocates storage for the object in the application, and no run-time memory allocation is required.

The object is therefore immediately available for initialization at startup.

In contrast to static instantiation, dynamic instantiation of kernel objects involves run-time

allocation of system memory and then initialization of the object before it can be used. Object

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Programmer's Guide, SR0610

deletion, in turn, involves invalidation of the object, and then return of the memory to the system.

Object creation and deletion are both dependent on dynamic memory allocation, usually with the

malloc( ) andfree( ) functions.

Applications using dynamic instantiation must therefore account for the possibility that the

system may run out of memory and that it may not be able to create the object (and resort to

some suitable error recovery process or abort). In addition, dynamic allocation is a relatively slow

operation that may block the calling task, and make system performance less deterministic.

Also in contrast to static instantiation, dynamic instantiation can be accomplished with a single

function call (for example, taskSpawn( ), semBCreate( ), and so on).

The code examples that follow illustrate the difference between coding dynamic and static

instantiation (but do not use any VxWorks object instantiation macros).

Dynamic Instantiation Code

struct my_object * pMyObj;

...

pMyObj = (struct my_object *) malloc (sizeof (struct my_object));

if (pMyObj != NULL)

{

fooObjectInit (pMyOjb);

return (OK);

}

else

{

/* failure path */

return (ERROR);

}

Static Instantiation Code

struct my_object myObj;

...

fooObjectInit(&myOjb);

/* myObj now ready for use */

Kernel Objects That can be Instantiated Statically

The following kernel objects can be instantiated statically:

• kernel tasks

• semaphores

• message queues

• watchdog timers

For detailed information, see

Task Creation and Activation on page 104, Semaphore Creation

and Use on page 130, Message Creation and Use on page 146, and Watchdog Timers on page

232.

Static Instantiation and Code Size

Compile-time declaration of objects does not occupy any space in an executable file, in a

VxWorks image, or in storage media (such as flash memory). If an object is declared at compile

time but not initialized, the compiler places it in the un-initialized data (bss) section. Un-

initialized data is required by the ANSI C standard to have a value of zero.

1 Kernel Applications

Static

Instantiation of Kernel Objects

While un-initialized data contributes to the run-time memory footprint, so does dynamic

allocation. In either case, the memory footprint would be the same.

Advantages of Static Instantiation

Static instantiation of kernel objects provides several advantages over dynamic instantiation:

• Static instantiation of objects is faster and more deterministic.

• Application logic is simpler because it does not have to account for the possibility that

dynamic allocation may fail.

• Static declaration of objects cannot fail, unless the program itself is too large to fit into system

memory.

Applications and Static Instantiation

Static instantiation of kernel objects provides notable advantages to real-time applications, and

most applications can make use of static instantiation to some degree. Most applications require

that some objects be available for the lifetime of their execution, and that they never be deleted.

These objects can therefore be statically instantiated. Using static instantiation whenever possible

makes applications more robust, deterministic, and fast.

NOTE: Static instantiation should only be used with kernel applications. It is not designed

for use with RTP (user-mode) applications.

Scope Of Static Declarations

Kernel objects are usually declared as global variables because the objects IDs are usually used

for inter-task communication and synchronization. However, they need not be global. An object

declaration can also be done at function scope provided the object stays in a valid scope for the

duration of its use.

Caveat With Regard to Macro Use

In order to ensure proper macro expansion, the task instantiation macros must use a backslash

character if the declaration or call that they implement is longer than one line. For example, the

following ensures that the static instantiation of a task with the VX_TASK_INSTANTIATE

macro will be handled properly by the compiler:

myTaskId = VX_TASK_INSTANTIATE(myTask, 100, 0, 4096, pEntry, 0,1,2,3,4,5,6,7,8,9);

Macro use is described in detail in Task Creation and Activation on page 104,Semaphore

Creation and Use on page 130, Message Creation and Use on page 146, and Watchdog Timers

on page 232.

Boot-Time Hook Function Facility

VxWorks hook function stubs that are called at specific points in the boot process can be used to

add your own boot-time functionality or test code. The stubs allow you to add code without

VxWorks

Programmer's Guide, SR0610

modifying the boot loader or operating system code itself, or without creating custom

components for your own code.

You can add code that performs time-critical operations before the operating system is fully up

and running, or code that overrides default features of the system. For example, you can use this

hook function functionality to do the following:

• Provide early feedback that the device is booting (print a message to an LCD display).

• Reset a watchdog timer during the boot process.

• Call custom diagnostic or test code.

• Start applications that do not require networking earlier in the initialization process.

• Read a GPIO for hardware version or test device status.

• Configure an FPGA early.

The boot-time hook function stubs are enabled by including stub-specific components in your

VxWorks configuration. The stubs must be called from the usrAppInit.c file (in your VIP project).

For information about using usrAppInit.c to automatically executing code after VxWorks has

booted, see

Using userAppInit() to Run Applications Automatically on page 10.

Boot-Time Hook Function Stubs and Components

The boot-time hook function stubs are enabled by including stub-specific components in your

VxWorks configuration.

For detailed information about the boot process, see the VxWorks 7 BSP Developer's Guide.

Hook Function Stub

Description and Required Component

usrPreKernelAppInit( ) Called at the beginning of usrInit( ), right after cacheLibInit( ). That

is, right after the board boots and before kernel initialization starts.

INCLUDE_USER_PRE_KERNEL_APPL_INIT

usrPostKernelAppInit( ) Called right after usrKernelCreateInit( ). That is, right after most of

the kernel core features are enabled. The I/O system and network

are not available at this point.

INCLUDE_USER_POST_KERNEL_APPL_INIT

usrPreNetworkAppInit( )

Called right before the network is initialized. At this point most of

the core kernel features including the I/O system are available.

INCLUDE_USER_PRE_NETWORK_APPL_INIT

Restrictions on Use

•

The stubs must be called from the usrAppInit.c file (in your VIP project).

•

For usrPreKernelAppInit( ), no VxWorks APIs can be used. Use only your own code (for

example, to initialize registers or light an LED).

1 Kernel Applications

Boot-Time

Hook Function Stubs and Components

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