ARM中断函数配置问题

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kingjie|

楼主 | 2007-5-5 21:42 | 只看该作者回帖奖励

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ARM, 中断函数, ic, AI, TE

__inline unsigned int AT91F_AIC_ConfigureIt (
    AT91PS_AIC pAic,  // arg pointer to the AIC registers
    unsigned int irq_id,     // arg interrupt number to initialize
    unsigned int priority,   // arg priority to give to the interrupt
    unsigned int src_type,   // arg activation and sense of activation
    void (*newHandler) (void) ) // arg address of the interrupt handler
{
    unsigned int oldHandler;
    unsigned int mask ;

    oldHandler = pAic->AIC_SVR[irq_id];

    mask = 0x1 << irq_id ;
    //* Disable the interrupt on the interrupt controller
    pAic->AIC_IDCR = mask ;
    //* Save the interrupt handler routine pointer and the interrupt priority
    pAic->AIC_SVR[irq_id] = (unsigned int) newHandler ;
    //* Store the Source Mode Register
    pAic->AIC_SMR[irq_id] = src_type | priority  ;
    //* Clear the interrupt on the interrupt controller
    pAic->AIC_ICCR = mask ;

    return oldHandler;
}
这个函数具体在做什么？什么时候调用？为什么要返回oldHandler？

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