| 摘要 |
PURPOSE:To efficiently control the instruction execution by inspecting the generation of an underflow exception, and outputting an exceptive generation predicting signal only when the generation of the underflow exception cannot be judged. CONSTITUTION:An exponential part intermediate result 101 is inputted, an underflow exceptive generation predicting signal 102 is outputted, and in order to correspond to both of single preceision and double precision operations, the exponential part intermediate result 101 is converted to data 107 of the same bit width and handled in a predicting circuit. Also, a constant 106 compared with the the signal 107 by a comparing circuit 110 is different at the time of single precision operation and at the time of double precision operation, therefore, a selector circuit 108 for selecting a suitable constant is added, and which constant is selected is designated by a signal 105. Subsequently, the comparing circuit compares the signal 107 and the signal 106, and when a value of the signal 107 is below a value of the signal 106, a signal value for showing a fact that generation of an underflow exception is predicted is outputted to the signal 102. In such a way, the control in predicting generation of an exception can be executed. |
