| 摘要 |
PURPOSE:To quickly perform processing by switching plural register sets consisting of plural registers to not only momently perform saving and restoring operations but also hold the contents of registers before saving. CONSTITUTION:When a switching control circuit 6 selects a register set 1a, writing of write data WD in a register specified with a register number AD is possible and the processing using the set 1a is performed. If a subroutine is called in this main routine, the circuit 6 switches the register set 1a to a register set 1b. Then, data of the set 1a is saved. If a second subroutine is called, the register set 1b is switched to a register set 1c similarly. The contents of specific registers in the preceding register set can be refereed to, based on write flags WF of write flag registers 5a-5c after switching and the processing is quickly performed.
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