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INSTRUCTION SET OVERVIEW
5.2.10
Debug
The processor supports debugging and monitoring of program activity through the use of trace
events. The following instructions support these debugging and monitoring tools:
modtc
modify trace controls
mark
mark
fmark
force mark
These all use the REG format. Trace functions are controlled with bits in the Trace Control (TC)
register which enable or disable various types of tracing. Other TC register flags indicate when an
enabled trace event is detected. Refer to
modtc
permits trace controls to be modified.
when breakpoint trace mode is enabled.
state of the breakpoint trace mode bits.
Other instructions that are helpful in debugging include
instruction can enable/disable trace fault generation. The
over breakpoint trace event generation. This instruction is used, in part, to load and control the
i960 Jx processor's breakpoint registers.
5.2.11
Atomic Instructions
Atomic instructions perform an atomic read-modify-write operation on operands in memory. An
atomic operation is one in which other memory operations are forced to occur before or after, but
not during, the accesses that comprise the atomic operation. These instructions are required to
enable synchronization between interrupt handlers and background tasks in any system. They are
also particularly useful in systems where several agents — processors, coprocessors or external
logic — have access to the same system memory for communication.
The atomic instructions are atomic add (
operand to be added to the value in the specified memory location.
specified memory location to be modified under control of a mask. Both instructions use the REG
format and can specify literals or local or global registers as operands. These instructions assert the
LOCK signal.
5-18
CHAPTER 9, TRACING AND
mark
causes a breakpoint trace event to be generated
fmark
generates a breakpoint trace independent of the
modpc
sysctl
instruction also provides control
) and atomic modify (
atadd
DEBUGGING.
and
. The
sysctl
modpc
).
causes an
atmod
atadd
atmod
causes bits in the
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