Bus synchronization apparatus and method

Abstract

Several techniques are used to optimize the transmission of signals or events from one bus to the other. In one aspect, the user of a chipset is permitted to choose whether the originating events (i.e. the events in response to which a destination event is to be generated on a destination bus) are to be generated synchronously or asynchronously with the clock signal on the destination bus. Whether synchronous or asynchronous generation is chosen, the chipset may perform a synchronization function in response to an originating bus predictor signal. The number of destination clock cycles to delay before generating the desired destination bus event is responsive to the relative frequencies of the clock signals on the two buses, thereby accommodating a wide variety of such relative frequencies. In another aspect, for events to be generated on a destination bus synchronously with a clock signal which is by specification stretchable, the destination bus event is generated promptly in response to the originating event and then the destination bus clock signal is stretched to make the destination bus event synchronous with the destination bus clock signal. The length of the stretch is responsive to the relative frequencies of the originating bus and destination bus clock frequencies. A synchronizer is used to generate the destination bus event synchronously with the destination bus clock signal. The user of the chipset can select which formula is to be applied.