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Section 11 User Break Controller (UBC)
Rev. 4.00 Sep. 14, 2005 Page 260 of 982
REJ09B0023-0400
11.3.5 Sequential Break
1. By setting the SEQ bit in BRCR to 1, the sequential break is issued when a channel B break
condition matches after a channel A break condition matches. A user break is not generated
even if a channel B break condition matches before a channel A break condition matches.
When channels A and B conditions match at the same time, the sequential break is not issued.
To clear the channel A condition match when a channel A condition match has occurred but a
channel B condition match has not yet occurred in a sequential break specification, clear the
SEQ bit in BRCR to 0.
2. In sequential break specification, the L/I/X/Y bus can be selected and the execution times
break condition can be also specified. For example, when the execution times break condition
is specified, the break condition is satisfied when a channel B condition matches with BETR =
H'0001 after a channel A condition has matched.
11.3.6 Value of Saved Program Counter
When a break occurs, the address of the instruction from where execution is to be resumed is
saved in the SPC, and the exception handling state is entered. If the L bus is specified as a break
condition, the instruction at which the break should occur can be clearly determined (except for
when data is included in the break condition). If the I bus is specified as a break condition, the
instruction at which the break should occur cannot be clearly determined.
1. When instruction fetch (before instruction execution) is specified as a break condition:
The address of the instruction that matched the break condition is saved in the SPC. The
instruction that matched the condition is not executed, and the break occurs before it. However
when a delay slot instruction matches the condition, the address of the delayed branch
instruction is saved in the SPC.
2. When instruction fetch (after instruction execution) is specified as a break condition:
The address of the instruction following the instruction that matched the break condition is
saved in the SPC. The instruction that matches the condition is executed, and the break occurs
before the next instruction is executed. However when a delayed branch instruction or delay
slot matches the condition, these instructions are executed, and the branch destination address
is saved in the SPC.
3. When data access (address only) is specified as a break condition:
The address of the instruction immediately after the instruction that matched the break
condition is saved in the SPC. The instruction that matches the condition is executed, and the
break occurs before the next instruction is executed. However when a delay slot instruction
matches the condition, the branch destination address is saved in the SPC.