//其中[=IF ,|=ELSE ,]= ENDIF, CODE32 表明一下操作都在ARM状态。这些都是伪操作这段理解为设定THUMCODE的值,然后确定,用户的程序是在ARM状态还是THUM状态。
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四、MACRO
$HandlerLabel HANDLER $HandleLabel
$HandlerLabel
sub sp,sp,#4 ;decrement sp(to store jump address)
stmfd sp!,{r0} USH the work register to stack
ldr r0,=$HandleLabel;load the address of HandleXXX to r0
ldr r0,[r0] ;load the contents(service routine start address) of HandleXXX
str r0,[sp,#4] ;store the contents(ISR) of HandleXXX to stack
ldmfd sp!,{r0,pc} OP the work register and pc(jump to ISR)
MEND