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Section 9 Exception Handling
Rev. 4.00 Sep. 14, 2005 Page 197 of 982
REJ09B0023-0400
Section 9 Exception Handling
Exception handling is separate from normal program processing, and is performed by a routine
separate from the normal program. For example, if an attempt is made to execute an undefined
instruction code or an instruction protected by the CPU processing mode, a control function may
be required to return to the source program by executing the appropriate operation or to report an
abnormality and carry out end processing. In addition, a function to control processing requested
by LSI on-chip modules or an LSI external module to the CPU may also be required.
Transferring control to a user-defined exception processing routine and executing the process to
support the above functions are called exception handling. This LSI has two types of exceptions:
general exceptions and interrupts. The user can execute the required processing by assigning
exception handling routines corresponding to the required exception processing and then return to
the source program.
A reset input can terminate the normal program execution and pass control to the reset vector after
register initialization. This reset operation can also be regarded as an exception handling. This
section describes an overview of the exception handling operation. Here, general exceptions and
interrupts are referred to as exception handling. For interrupts, this section describes only the
process executed for interrupt requests. For details on how to generate an interrupt request, refer to
section 10, Interrupt Controller (INTC).