1 logic utilization
- 题目:Rank the following operations from lowest utilization to highest. Assume that all variables are 32-bit integers,that the operations are implemented using LUTs ony and that the synthesiser will produce an optimal digital circuit.
1.X = Y * 3
2.X = Y * 8
3.X = Y + 2
4.X = Y + 32 - 解析:
1.X = Y * 3
2.X = Y * 8
综合后的电路通过在低位补3个0来实现乘8。
3.X = Y + 2
4.X = Y + 32
对比3、4,他们的不同在于加数。当x与2相加时,2的二进制形式为:2’b10,x的最低位可保持不变,其余位参与运算。当x与32相加时,32的二进制形式为:2’b10_0000,x的低5位可保持不变,其余位参与运算。
- 答案:2431