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// Programmable Interrupt Controller Emulator

//

// This class emulates some of the functionality of the interrupt

// controller. Edge sensing on the interrupt inputs is not currently

// supported. The edge sensing on the clock interrupts is emulated

// by resetting the interrupt input when the PIC recieves the

// command to acknowledge the edge sensitive interrupt and only

// driving the interrupt signal true by the timer. The timers

// effectively act like pulse generators which provide only a

// positive transition to the clock signal. The negative 

// transition is supplied when the interrupt is acknowledged.

// In the real system the clock generator provides a square wave

// output for the interrupts so edge sensing is necessary.

// It's faked out so that from the perspective of the BIOS

// software it looks the same.

        bool edges[16];         // edge sensitive