System Development and Debugging
MPC885 PowerQUICC Family Reference Manual, Rev. 2
53-4
Freescale Semiconductor
Table 53-4
describes instruction types as they are identified by VF encodings.
53.1.4
Program Trace Special Cases
The following sections describe special cases of program trace implemented on the MPC885.
53.1.4.1
Queue Flush Information Special Case
There is one special case where the queue flush information is expected on the VF pins after an instruction
fetch encoding of VF = 0b1xx. This case is where an instruction-type VF indications of b1xx is followed
by an indication of VF = 0b111. This indication of VF = 0b111 should be interpreted as an instruction fetch
type encoding, as described by
Table 53-4
. This is easily monitored since the only case where this can
happen is when VF = 111 and the maximum number of possible queue flushes is five.
53.1.4.2
Program Trace When In Debug Mode
When entering debug mode an interrupt/exception taken is reported on the VF pins (VF = 0b100) and a
cycle marked with the program trace cycle is made externally visible. When the core is in debug mode, VF
= 0b000 and VFLS = 0b11. For more information on debug mode, see
Section 53.3, “Development System
Interface.”
100
Four instructions were flushed from the instruction queue
Instruction type information
101
Five instructions were flushed from the instruction queue
Instruction type information
110
Reserved
Instruction type information
111
See VF = 0b111 entry in
Table 53-4
—
Table 53-4. VF Pins Encoding: Instruction Fetch Types
VF
Instruction Type
VF Next Clock Holds
000
None
More instruction type
information
001
Sequential
1
1
See
Section 53.1.4.3, “Sequential Instructions Marked as Indirect Branch.”
010
Branch (direct or indirect) not taken
011
This instruction is marked with the program trace cycle attribute in response to changing
the state of TECR[VSYNC] in the development port.
100
Interrupt/exception taken, the target is marked with the program trace cycle attribute
Queue flush
information
2
2
Unless the next clock VF = 111, see
Section 53.1.4.1, “Queue Flush Information Special Case.”
101
Branch indirect taken,
rfi
,
mtmsr
,
isync
and in some cases
mtspr
, the target is marked
with the program trace cycle attribute
1
110
Branch direct taken
111
Branch (direct or indirect) not taken
Table 53-3. VF Pins Encoding: Instruction Queue Flushes (continued)
VF
Instructions Flushed
VF Next Cycle Holds
Summary of Contents for PowerQUICC MPC870
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