arm 初始化代码中的{CONFIG}语句疑问

 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

Table 3.3 lists the built-in variables defined by the ARM assembler.

Table 3.3. 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 of armasm.
|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 value 32 if the assembler is assembling ARM code, or 16 if it is assembling Thumb code.
{CPU}	Holds the name of the CPU selected by the --device option.
{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 --device option.
{FPU}	Holds the name of the FPU. The default FPU name is selected by the --device option.
{INPUTFILE}	Holds the name of the current source file.
{INTER}	Has the boolean value True if /inter is 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. The OPT directive 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 the STR pc,[…] or STM Rb,{…, pc} instruction and the value of pc stored out. This varies depending on the device specified.
{ROPI}	Has the boolean value True if /ropi is set. The default is False.
{RWPI}	Has the boolean value True if /rwpi is set. The default is False.
{VAR} or @	Current value of the storage area location counter.

 

Built-in variables cannot be set using the SETA, SETL, or SETS directives. 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. See CPU names for valid values for {CPU} and {ARCHITECTURE}. See FPU names for valid values for {FPU}. Relational operations on these built-in variables will not match with strings that contain an incorrect case.

Table 3.4 lists the built-in Boolean constants defined by the ARM assembler.

Table 3.4. Built-in Boolean constants

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