128位加法器优化设计：64位加法运算+2-1多路选择器。并在关键路径上添加寄存器，降低延迟。 testbench可以测试优化的效果，在ISE中做过综合，能跑到200+MHz-128-bit adder optimization design: 64-bit adder+ 2-1MUX. In the key path, there are regs to improve the performance and reduce the delay time. you use the tes