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4-2

32170/32174 Group User's Manual (Rev. 2.1)

EIT

4.1 Outline of EIT

If some event occurs when the CPU is executing an ordinary program, it may become necessary to

suspend the program being executed and execute another program. Events like this one are

referred to by a generic name as EIT (Exception, Interrupt, and Trap).

(1) Exception

This is an event related to the context being executed. It is generated by an error or violation

during instruction execution. In the M32R/ECU, this type of event includes Address Exception

(AE) and Reserved Instruction Exception (RIE).

(2) Interrupt

This is an event generated irrespective of the context being executed. It is generated in hardware

by a signal from an external source. In the M32R/ECU, this type of event includes External

Interrupt (EI), System Break Interrupt (SBI), and Reset Interrupt (RI).

(3) Trap

This refers to a software interrupt generated by executing a TRAP instruction. This type of event

is intentionally generated in a program as in the OS's system call by the programmer.

EIT

Exception

Reserved Instruction Exception (RIE)

Address Exception (AE)

Interrupt

Reset Interrupt (RI)

System Break Interrupt (SBI)

External Interrupt (EI)

Trap

TRAP

Figure 4.1.1 Classification of EITs

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