VxWorks入门（一）：VxWorks Vs Linux

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1, VxWorks的特点：

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■All functions exist in the same "space".

►Name clashes may appear between different modules (libraries).

►Use unique names (with prefix) for global functions!

●Wrong: config, test, read_bi

●Right: drvXyConfig, fooTest, devAbc_read_bi

►Or make functions static.

■vxWorks has no main function.

■Every function (including the shell) can call any other function.

►You don’t start programs from the shell, you call functions.

►When name clash happens, you might call the wrong function.

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■Ending a thread does not clean up system resources.

2, VxWorks中不同模块下相同名字的全局变量仍占用同一块内存；

static可让变量仅在一个源文件中生效；

可能的内存问题：

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■Pro: Functions and threads can easily …

►exchange large amounts of data by reference (pointers).

►access any hardware register (e.g. VME bus).

■Con: Functions and threads can easily …

►overrun allocated memory or stack size (esp. with arrays)

►overwrite system tables. (e.g. interrupt handler table at NULL)

►overwrite program code.

►modify global variables of other modules (e.g. drivers).

3, 入门指导：

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■Online help: http://vxworks.web.psi.ch

►Important for beginners:
VxWorks Programmer's Guide, Chapter 2

●All about tasks, semaphores, watchdog timers, interrupts

►Always helpful:
vxWorks Reference Manual

●All vxWorks system functions

■Run-time help: Type help on the vxWorks shell.

4，VxWorks shell使用注意：
1）最多只能传10个参数；
2）PPC结构中float和double无效；
3）可以直接使用shell创建全局变量；
5，写程序应注意以下错误处理：

■Error checking is the key to a stable system.

►Stability is limited by the weakest point!

■Check arguments to API functions (esp. shell functions)

►Never trust a user! Not even yourself.

■Always check pointer arguments for validity.

►Writing to NULL overwrites the interrupt handler table!

■Check results of system functions (malloc, fopen, …)

►System functions may fail and return NULL or ERROR.

►Using these values unchecked may crash the system much later.

■Check for "impossible" values (e.g. in case constructs

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