arm 初始化代码中的{CONFIG}

ARM9 SC2440和2410得初始化代码中有下面一个定义:

GBLL THUMBCODE

[ {CONFIG} = 16

THUMBCODE SETL{TRUE}

CODE32

|

THUMBCODE SETL{FALSE}

]

网上的朋友有问下面问题的，我也有疑惑，从ARM官方网站查到了答案。特此列出。

请问代码里的 {CONFIG} 代表什么含义，如何知道它是不是等于为16

是某处定义的某个变量？

还是编译的时候某个配置选项？

用{}括起来代表什么含义

CONFIG 是ADS1.2编译器内建变量，还有其他一些内建变量。

Built-in variables and constants

Table3.3lists the built-in variables defined by the ARM assembler.

Table3.3.Built-in variables

{ARCHITECTURE}	Holds the name of the ARM architecture selected by the --device option.
{AREANAME}	Holds the name of the current AREA.
{ARMASM_VERSION}	Holds an integer that increases with each version ofarmasm.
|ads$version|	Has the same value as{ARMASM_VERSION}.
{CODESIZE}	Is a synonym for{CONFIG}.
{COMMANDLINE}	Holds the contents of the command line.
{CONFIG}	Has the value32if the assembler is assembling ARM code, or16if it is assembling Thumb code.
{CPU}	Holds the name of the CPU selected by the--deviceoption.
{ENDIAN}	Has the value“big”if the assembler is in big-endian mode, or“little”if it is in little-endian mode. The default value is selected by the--deviceoption.
{FPU}	Holds the name of the FPU. The default FPU name is selected by the--deviceoption.
{INPUTFILE}	Holds the name of the current source file.
{INTER}	Has the boolean value True if/interis set. The default is False.
{LINENUM}	Holds an integer indicating the line number in the current source file.
{OPT}	Value of the currently-set listing option. TheOPTdirective can be used to save the current listing option, force a change in it, or restore its original value.
{PC}or.	Address of current instruction.
{PCSTOREOFFSET}	Is the offset between the address of theSTRpc,[…]orSTMRb,{…,pc}instruction and the value of pc stored out. This varies depending on the device specified.
{ROPI}	Has the boolean value True if/ropiis set. The default is False.
{RWPI}	Has the boolean value True if/rwpiis set. The default is False.
{VAR}or@	Current value of the storage area location counter.

Built-in variables cannot be set using theSETA,SETL, orSETSdirectives. They can be used in expressions or conditions, for example:

IF {ARCHITECTURE} = "4T"

The built-in variable|ads$version|must be all in lowercase. The names of the other built-in variables can be in uppercase, lowercase, or mixed. For example:

IF {CpU} = "ARM7TDMI"

Note

All built-in string variables contain case-sensitive values. SeeCPU namesfor valid values for{CPU}and{ARCHITECTURE}. SeeFPU namesfor valid values for{FPU}. Relational operations on these built-in variables will not match with strings that contain an incorrect case.

Table3.4lists the built-in Boolean constants defined by the ARM assembler.

Table3.4.Built-in Boolean constants

{FALSE}	Logical constant false.
{TRUE}	Logical constant true.

源文档 <http://blog.csdn.net/yanglijing/article/details/4687173>