Command Dictionary Compress Patterns
FastScan and FlexTest Reference Manual, V8.6_4 2-149
Compress Patterns
Tools Supported: FastScan and FlexTest
Scope: Atpg mode
Usage
For FastScan
COMpress PAtterns [passes_integer] [-Reset_au] [-MAx_useless_passes integer]
[-MIn_elim_per_pass number]
For FlexTest
COMpress PAtterns [passes_integer] [-Force] [-MAx_useless_passes integer]
[-MIn_elim_per_pass number]
Description
Compresses patterns in the current test pattern set.
The Compress Patterns command performs static pattern compression on the
current test pattern set by repeating fault simulation for the patterns in either
reverse or random order and selecting only those patterns required for detection.
The passes_integer argument specifies the number of pattern compression passes.
The first pattern compression pass runs in reverse order and then alternates
between random and reverse for additional passes. If you do not specify a
passes_integer argument, the tool performs only a single compression pass.
FastScan Specifics
If you specify the -Reset_au option, then when FastScan performs pattern
compression, it selects the AU faults for later fault simulation. If during pattern
compression these AU faults simulate as possible-detected, the tool labels them as
PU (possible-detected—ATPG_untestable) and they receive test coverage credit
as possible-detected faults. If the number of pattern compression passes is greater
than one, FastScan only performs the resetting of the AU faults for the first pass.
The Compress Patterns command has a residual memory effect. The initial mode
(reverse/random) is not fixed. Instead, it toggles back and forth, starting with the
mode last used in the same run. FastScan always starts with the reverse order at
invocation.