| 摘要 |
A recursive carry-select substitution operation is used to optimize the design of an incrementer and similar logic devices. A carry look-ahead incrementer features XOR gates in which the XOR gates in one or more MSBs of the incrementer can be pushed back by substituting an equivalent carry-select circuit, the carry-select circuit including a multiplexer. The push back operations occur until both inputs of the XOR gates are fed by inverters, allowing an entire stage of inverters to be eliminated in the circuit. Where a bit path includes a buffer comprising two inverters, the inverter size is selected so as to execute as a single stage. The result is a carry look-ahead incrementer in which a stage is eliminated.
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