| 摘要 |
PURPOSE:To eliminate an overhead and to speed up the execution of a loop by adding an escape control circuit, which discriminates the escape condition of the loop and makes an escape, to a program counter circuit, and performing escape processing through hardware. CONSTITUTION:When an escape control circuit is not in operation, a valid flip- flop 4 is reset and the output of an AND gate 6 stays at a level 0. A selecting circuit 7 connects the output of a program counter updating circuit 9 to a program counter 8 while the output of the AND gate 6 is at 0. When, however, the escape control circuit is validated, a coincidence output from a comparing circuit 5 is applied to the selecting circuit 7 through the AND gate 6. Therefore, the selecting circuit 7 couples the output of an escape address register 3 with the program counter 8 as a substitute for the output of said circuit 9. Consequently, once a next execution instruction is taken out of an escape address set in the counter 8, the valid flip-flop 4 is reset, thereby completing loop escaping operation. |
