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Section 9 Exception Handling
Rev. 4.00 Sep. 14, 2005 Page 214 of 982
REJ09B0023-0400
An Exception Retained in Repeat Control Period: In the repeat control period, an interrupt or
some exception will be retained to prevent an exception acceptance at an instruction where
returning from the exception cannot be performed correctly. For details, refer to repeat loop
program example 1 to 4. In the examples, exceptions generated at instructions indicated as [B],
[C], [C1], or [C2], the following processing is executed.
• Interrupt, DMA address error
An exception request is not accepted and retained at instructions [B] and [C]. If an instruction
indicates as [A] is executed the next time, an exception request is accepted.* As shown in
example 1 to 4, any interrupt or DMA address error cannot be accepted in a repeat loop
consisting of four instructions or less.
Note: * An interrupt request or a DMA address error exception request is retained in the
interrupt controller (INTC) and the direct memory access controller (DMAC) until the
CPU can accept a request.
• User break before instruction execution
A user break before instruction execution is accepted at instruction [B], and an address of
instruction [B] is saved in the SPC. This exception cannot be accepted at instruction [C] but
the exception request is retained until an instruction [A] or [B] is executed the next time. Then,
the exception request is accepted before an instruction [A] or [B] is executed. In this case, an
address of instruction [A] or [B] is saved in the SPC.
• User break after instruction execution
A user break after instruction execution cannot be accepted at instructions [B] and [C] but the
exception request is retained until an instruction [A] or [B] is executed the next time. Then, the
exception request is accepted before an instruction [A] or [B] is executed. In this case, an
address of instruction [A] or [B] is saved in the SPC.
Table 9.5 Exception Acceptance in the Repeat Loop
Exception Type Instruction [B] Instruction [C]
Interrupt Not accepted Not accepted
DMA address error Not accepted Not accepted
User break before instruction execution Accepted Not accepted
User break after instruction execution Not accepted Not accepted