| 摘要 |
PURPOSE:To prevent overhead by selecting any of the 1st designation means designating the kind of rounding and the 2nd designation means designating the kind of rounding through the identification of a prescribed instruction specifically so as to execute the rounding. CONSTITUTION:Each bit of a 4-bit FF 1 set by a write instruction or the like of a CPU corresponds to a round mode, only one bit in the 4-bit is set to have a logical 1 and its value is outputted to a rounding execution circuit 6 according to a priority circuit 5 when the value of a 1-bit FF 4 is 0. Further, when the value of the FF 4 is logical 1, the special instruction is decoded by the instruction decoder 2 and when a line corresponding to signal lines inputted to a PLA 3 is logical 1, the programmed output line is brought into logical 1 and its output is inputted from the PLA 3 to the circuit 6 according to the circuit 5. |
