| 摘要 |
PURPOSE:To attain the high speed conversion of floating point form data to prescribed fixed point format data by shifting the bits of only the number of shifts with a mantissa part as an index part and with the number of cut-off digits as the number of shifts by fixed point format data. CONSTITUTION:An adding means 1 prepares a sum 6 with a value 5 to invert the value of an index part 4 and respective digits of the binary expression of the number of the digits of the prescribed digits or below and obtains the value related to the number of shifts. A selecting means 2 identifies the value of the sum 6, and at the time of being the size in the prescribed range, the value composed of the bit column of the prescribed digit or below of the sum 6 is outputted as the number 7 of controls. At the time of being smaller than the prescribed range, the prescribed value to obtain the result of the underflow is outputted as the number 7 of controls and at the time of being larger than the range, the prescribed value to obtain the result of the overflow is outputted as the number 7 of controls respectively. A memory 3 has respective storing positions corresponding to the number 7 of the controls concerning all respective values capable of obtaining by a mantissa part 8. By the address specified by the mantissa part 8 and the number 7 of the controls, the necessary data format converting result 9 is held at the storing position read from the memory 3. |
