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4
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/E, 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/E, 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
Figure 4.1.1 Classification of EITs
Exception
Interrupt
Trap
4-2
Reserved Instruction Exception (RIE)
Address Exception (AE)
Reset Interrupt (RI)
System Break Interrupt (SBI)
External Interrupt (EI)
TRAP
EIT
4.1 Outline of EIT
Ver.0.10
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