Figure 9-1. 80960Jx Trace Controls (Tc) Register - Intel i960 Jx Developer's Manual

TRACING AND DEBUGGING
9.1.1 Trace Controls (TC) Register
The TC register (Figure 9-1) allows software to define conditions that generate trace events.
Trace Mode Bits
Instruction Trace Mode - TC.i
Branch Trace Mode - TC.b
Call Trace Mode -TC.c
Return Trace Mode - TC.r
Pre-Return Trace Mode - TC.p
Supervisor Trace Mode - TC.s
Mark Trace Mode - TC.mk
31 28 24
d d i i
1 0 1 0
f f f f
Reserved

Figure 9-1. 80960Jx Trace Controls (TC) Register

The TC register contains mode bits and event flags. Mode bits define a set of tracing conditions
that the processor can detect. For example, when the call-trace mode bit is set, the processor
generates a trace event when a call or branch-and-link operation executes. See
(pg. 9-3). The processor uses event flags to monitor which breakpoint trace events are generated.
A special instruction, modify-trace-controls (
On initialization, the TC register is read from the Control Table.
clear trace mode bits as required. Updating TC mode bits may take up to four non-branching
instructions to take effect. Software can access the breakpoint event flags using
processor automatically sets and clears these flags as part of its trace handling mechanism: the
breakpoint event flag corresponding to the trace being serviced is set in the TC while servicing a
breakpoint trace fault; the TC event flags are cleared upon return from the trace fault handler.
When the program is not in a trace fault handler, or when the trace is not for breakpoints, the TC
event bits are clear. On the i960 Jx processor, TC register bits 0, 8 through 23 and 28 through 31
are reserved. Software must initialize these bits to zero and cannot modify them afterwards.
9-2
20 16
12
Hardware Breakpoint Event Flags
Instruction-Address Breakpoint 0 - TC.i0f
Instruction-Address Breakpoint 1 - TC.i1f
Data-Address Breakpoint 0 - TC.d0f
Data-Address Breakpoint 1 - TC.d1f
), allows software to modify the TC register.
modtc
m
s p r c b i
k
8 4 0
section 9.2
modtc can then be used to set or
modtc . The