Motorola MPC533 Reference Manual page 881

The trace information that is generated by RCPU is ideally suited for off-line software
oriented processing, where there is the ability to trace back and recover from flushed
queues.
21.1.6.2 RCPU Branch Trace Indicators
The RCPU supports program trace by providing information on the status of the instruction
decode, instruction queue flush and history buffer flush. For more information, consult the
section on development support in the RCPU Reference Manual. The branch trace
indicators from the RCPU are the VF and the VFLS signals.
The VF signals indicate the type for the current instruction decoded and the outcomes of
change-of-flow instructions. They also indicate the number of instructions flushed from the
instruction prefetch queue on change of flow. This indication is in the clock following the
indication of change of flow. For details on VF instruction type encoding and VF queue
flush Information refer to Table 21-6 and Table 21-7 respectively.
VF
000 None
001 Sequential
010 Branch (direct or indirect) NOT taken
011 VSYNC was asserted/negated and therefore the next
instruction will be marked with program trace cycle attribute
100 Interrupt/Exception taken – the target instruction fetch will be
marked with program trace cycle attribute.
101 Branch Indirect taken, rfi, mtmsr, isync and in some cases
mtspr – the target instruction fetch will be marked with
program trace cycle attribute.
110 Branch direct taken
111 Branch (direct or indirect) NOT taken (misprediction)
The RCPU VF signals indicate (instruction pre-fetch) queue flush information in the clock
following a taken change-of-flow indication. This encoding is as follows.
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Table 21-6. VF Instruction Type Encoding
Instruction Type
Chapter 21. Development Support
Program Flow Tracking
Next VF Encoding
Instruction Type
Queue Flush Information
21-11