| 摘要 |
PURPOSE:To shift the most significant digit bit of data stored in a register to a specific position at a high speed by dividing the data stored in the register into several blocks, identifying the block containing the most significant digit bit, and supplying the position of the most significant digit bit in the block and the data in the block to a table ROM. CONSTITUTION:Sixteen-bit data is divided into four 4-bit blocks, and an all-0 decision circuit 7 decides on whether the bits of the data in the 1st block are all 0 or not in the 1st cycle to output 00 when so, and inputs data 000 in the 1st block to the table ROM9. The decision circuit 7 decides on whether the bits of data in the 2nd block are all 0 or not in the 2nd cycle to output a code value 10 indicating that the 2nd block contains the most significant digit bit, and outputs the data in the 2nd block to the table ROM9. A selecting circuit 8 outputs the data in the 3rd block to the table ROM9 in the 3rd cycle. The selecting circuit 8 outputs the data in the 4th block to the table ROM9 in the 4th cycle as well as in the 3rd cycle. |
