;/////////////////////////////////////////////

;option.inc

_ISR_STARTADDRESS    EQU 0x33ffff00


;2440addr.inc
INTOFFSET EQU  0x4a000014    ;Interruot request source offset

;/////////////////////////////////////////////

;init.s

;/////////////////////宏

         MACRO

$HandlerLabel HANDLER $HandleLabel

$HandlerLabel

    sub    sp,sp,#    ;decrement sp(to store jump address)

    stmfd    sp!,{r0}    ;PUSH the work register to stack(lr does t push because it return to original address)

    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,#]      ;store the contents(ISR) of HandleXXX to stack

    ldmfd   sp!,{r0,pc}     ;POP the work register and pc(jump to ISR)

    MEND

;////////////////////////;入口处定义中断跳转

ResetEntry

    b    ResetHandler

    b    HandlerUndef    ;handler for Undefined mode

    b    HandlerSWI        ;handler for SWI interrupt

    b    HandlerPabort    ;handler for PAbort

    b    HandlerDabort    ;handler for DAbort

    b    .                ;reserved

    b    HandlerIRQ        ;handler for IRQ interrupt

    b    HandlerFIQ        ;handler for FIQ interrupt

    HandlerFIQ      HANDLER HandleFIQ

    HandlerIRQ      HANDLER HandleIRQ

    HandlerUndef    HANDLER HandleUndef

    HandlerSWI      HANDLER HandleSWI

    HandlerDabort   HANDLER HandleDabort

    HandlerPabort   HANDLER HandlePabort

IsrIRQ                            ;定义IsrIRQ函数

    sub      sp,sp,#           ;reserved for PC

    stmfd    sp!,{r8-r9}

    ldr    r9,=INTOFFSET

    ldr    r9,[r9]

    ldr    r8,=HandleEINT0

    add    r8,r8,r9,lsl #        ;r8=r8+(r9*4)

    ldr    r8,[r8]

    str    r8,[sp,#]

    ldmfd    sp!,{r8-r9,pc}    

ResetHandler

    ;....此处省略，其他操作如看门狗、sram初始化、堆栈初始化等 ....     

　　 ;Setup IRQ handler

    ldr    r0,=HandleIRQ           ;This routine is needed

    ldr    r1,=IsrIRQ              ;if there is not 'subs pc,lr,#4' at 0x18, 0x1c

    str    r1,[r0]　　　　　　　　　　;这样，在地址值为HandleIRQ(0x33FF_FF1C)处，装着IsrIRQ函数指针。

    ;....此处省略，拷贝程序、跳转main等....

;///////////////////////////////////////////////////////////////;定义中断地址

    ^   _ISR_STARTADDRESS        ; _ISR_STARTADDRESS=0x33FF_FF00

HandleReset     #           ;0x33FF_FF04

HandleUndef     #           ;0x33FF_FF08

HandleSWI       #           ;0x33FF_FF0c

HandlePabort    #           ;0x33FF_FF10

HandleDabort    #           ;0x33FF_FF14

HandleReserved  #           ;0x33FF_FF18

HandleIRQ       #           ;0x33FF_FF1C

HandleEINT0     #           ;@0x33FF_FF20

HandleEINT1 # 4
HandleEINT2 # 4
HandleEINT3 # 4
HandleEINT4_7 # 4
HandleEINT8_23 # 4
HandleCAM # 4 ; Added for 2440.
HandleBATFLT # 4
HandleTICK # 4
HandleWDT # 4
HandleTIMER0 # 4
HandleTIMER1 # 4
HandleTIMER2 # 4
HandleTIMER3 # 4
HandleTIMER4 # 4
HandleUART2 # 4
;@0x33FF_FF60
HandleLCD # 4
HandleDMA0 # 4
HandleDMA1 # 4
HandleDMA2 # 4
HandleDMA3 # 4
HandleMMC # 4
HandleSPI0 # 4
HandleUART1 # 4
HandleNFCON # 4 ; Added for 2440.
HandleUSBD # 4
HandleUSBH # 4
HandleIIC # 4
HandleUART0 # 4
HandleSPI1 # 4
HandleRTC # 4
HandleADC # 4

HandlerIRQ      HANDLER HandleIRQ

展开：

HandlerIRQ

    sub    sp,sp,#         ;decrement sp(to store jump address)

    stmfd    sp!,{r0}       ;PUSH the work register to stack(lr does t push because it return to original address)

    ldr     r0,=HandleIRQ   ;load the address of HandleIRQ to r0

    ldr     r0,[r0]         ;load the contents(service routine start address) of HandleIRQ

                            ;这里的contents是参照下面Setup IRQ handler ，为IsrIRQ函数指针

    str     r0,[sp,#]      ;store the contents(ISR) of HandleIRQ to stack

    ldmfd   sp!,{r0,pc}     ;POP the work register and pc(jump to ISR)

    MEND

IsrIRQ

    sub    sp,sp,#       ;reserved for PC

    stmfd    sp!,{r8-r9}

    ldr    r9,=INTOFFSET

    ldr    r9,[r9]

    ldr    r8,=HandleEINT0

    add    r8,r8,r9,lsl #

    ldr    r8,[r8]  ;//r8 = HandleEINT0 + INTOFFSET寄存器的值*4 ;这里对应的是C代码中定义的中断响应函数的地址。怎么对应上的？见如下的代码：

    str    r8,[sp,#]

    ldmfd    sp!,{r8-r9,pc}

C代码中：

关联中断处理函数和启动代码中的中断地址。

//option.h

#define _ISR_STARTADDRESS     0x33ffff00


//addr.h

#define pISR_UART1        (*(unsigned *)(_ISR_STARTADDRESS+0x7c))
#define pISR_EINT0 (*(unsigned *)(_ISR_STARTADDRESS+0x20))  ;0x33FF_FF20

//IsrBind()  // isr_init.c 
pISR_UART1=(unsigned int)ProcomUart1IsrFunction; 在逻辑代码中，地址值是绝对的，因此C中的_ISR_STARTADDRESS正是启动代码中的_ISR_STARTADDRESS。 那pISR_UART1表示的就是*（HandleUART1）。pISR_EINT0就是*（HandleEINT0）.

这里可以得出：我们的C代码中可以在pISR_EINT0里面分发外部中断，也可以直接绑定到具体中断源。这无非是一个中断地址表和中断处理函数的对应。

//先后关系：
硬件中断发生
--->
中断相关寄存器的值产生相应变化(INT_OFFSET反映了具体的外部中断源)
--->

b HandlerIRQ()

--->

HandleIRQ()

--->

IsrIRQ()

--->//如上图IsrIRQ的解析所示，根据INT_OFFSET和事先制定的地址对照表，跳转到C中初始化时绑定的中断函数

one of irq_funcs