离上次真正写历程已经有10天的时间了。国庆嘛，自己给自己放了几天假——耍耍游戏下下棋什么的。
其实这次写触屏的驱动和对ARM中中断的过程的了解也花了不少时间和脑力。
我就简单分享一下CPU执行某个中断的条件吧，也是我自己的理解，如果有错还请大家指正（以IRQ中断为例吧）： 在程序状态寄存器中（CPSR寄存器）i 位为IRQ中断禁止位，若这一位置1那么所有的IRQ中断都不会被CPU响应，如果这一位被清0，CPU也不一定会响应某一个或某些中断（就像是一个总开关）。所以，要想让CPU执行ＩＲＱ中断，ＣＰＲＳ中的ｉ位必须要清０！ 在２４４０的ＣＰＵ中还有两个中断屏蔽寄存器：INTMSK（中断屏蔽寄存器）和INTSUBMSK（子中断屏蔽寄存器）。如果相应的屏蔽位置1，寄存器指出某个中断无效。如果INTMSK 的一个中断屏蔽位是0，中断将被正常的服务。 2440一共有60个中断源，某些中断源又有N个子中断，如：INT_UART0中断，它下面就还有INT_RXD0,INT_TXD0,INT_ERR0三个了中断源。要让CPU执行INT_RXD0的中断服务就要让INTMSK和INTSUBMSK中对应位清0！
 
#define pISR_EINT0 (*(unsigned *)(_ISR_STARTADDRESS+0x20))
#define pISR_EINT1 (*(unsigned *)(_ISR_STARTADDRESS+0x24))
#define pISR_EINT2 (*(unsigned *)(_ISR_STARTADDRESS+0x28))
#define pISR_EINT3 (*(unsigned *)(_ISR_STARTADDRESS+0x2c))
#define pISR_EINT4_7 (*(unsigned *)(_ISR_STARTADDRESS+0x30))
#define pISR_EINT8_23 (*(unsigned *)(_ISR_STARTADDRESS+0x34))
#define pISR_CAM (*(unsigned *)(_ISR_STARTADDRESS+0x38)) // Added for 2440.
#define pISR_BAT_FLT (*(unsigned *)(_ISR_STARTADDRESS+0x3c))
#define pISR_TICK (*(unsigned *)(_ISR_STARTADDRESS+0x40))
#define pISR_WDT_AC97 (*(unsigned *)(_ISR_STARTADDRESS+0x44))//Changed to pISR_WDT_AC97 for 2440A
#define pISR_TIMER0 (*(unsigned *)(_ISR_STARTADDRESS+0x48))
#define pISR_TIMER1 (*(unsigned *)(_ISR_STARTADDRESS+0x4c))
#define pISR_TIMER2 (*(unsigned *)(_ISR_STARTADDRESS+0x50))
#define pISR_TIMER3 (*(unsigned *)(_ISR_STARTADDRESS+0x54))
#define pISR_TIMER4 (*(unsigned *)(_ISR_STARTADDRESS+0x58))
#define pISR_UART2 (*(unsigned *)(_ISR_STARTADDRESS+0x5c))
#define pISR_LCD (*(unsigned *)(_ISR_STARTADDRESS+0x60))
#define pISR_DMA0 (*(unsigned *)(_ISR_STARTADDRESS+0x64))
#define pISR_DMA1 (*(unsigned *)(_ISR_STARTADDRESS+0x68))
#define pISR_DMA2 (*(unsigned *)(_ISR_STARTADDRESS+0x6c))
#define pISR_DMA3 (*(unsigned *)(_ISR_STARTADDRESS+0x70))
#define pISR_SDI (*(unsigned *)(_ISR_STARTADDRESS+0x74))
#define pISR_SPI0 (*(unsigned *)(_ISR_STARTADDRESS+0x78))
#define pISR_UART1 (*(unsigned *)(_ISR_STARTADDRESS+0x7c))
#define pISR_NFCON (*(unsigned *)(_ISR_STARTADDRESS+0x80)) // Added for 2440.
#define pISR_USBD (*(unsigned *)(_ISR_STARTADDRESS+0x84))
#define pISR_USBH (*(unsigned *)(_ISR_STARTADDRESS+0x88))
#define pISR_IIC (*(unsigned *)(_ISR_STARTADDRESS+0x8c))
#define pISR_UART0 (*(unsigned *)(_ISR_STARTADDRESS+0x90))
#define pISR_SPI1 (*(unsigned *)(_ISR_STARTADDRESS+0x94))
#define pISR_RTC (*(unsigned *)(_ISR_STARTADDRESS+0x98))
#define pISR_ADC (*(unsigned *)(_ISR_STARTADDRESS+0x9c))
当程序发生中断的时候，程序指针就会跳转到相应的地址执行程序，此地址中再存放一条跳转到中断服务程序的指令。（如果在中断服务程序里面查询SUBSRCPND中对应位的情况就可以判断中哪一个子中断源发生了中断）（个人理解，仅供参考）
这是本人写好的程序（触屏切换图片）: http://www.tudou.com/programs/view/NJjDms5QoqI/
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