NAME

extcheck - check hierarchical ext (5) files for global node connectivity and summarize number of fets, nodes, etc.

SYNOPSIS

extcheck [ -c cthresh ] [ -p path ] [ -r rthresh ] [ -s sym=value ] [ -C ] [ -R ] [ -S symfile ] [ -T tech ] root

DESCRIPTION

Extcheck will read an extracted circuit in the hierarchical ext (5) representation produced by Magic, check to ensure that all global nodes (those to which a label ending in an exclamantion point is attached) are fully connected in the layout, and then print a count of the number of various items (nodes, fets, etc) encountered while flattening the circuit. The root of the tree to be processed is the file root.ext; it and all the files it references are recursively flattened.

The following options are recognized:

-c cthresh
Set the capacitance threshold to cthresh femtofarads. Extcheck will count the number of explicit internodal capacitors greater than cthresh, the number of nodes whose capacitance is greater than cthresh, as well as the total number of nodes. (Other programs such as ext2sim (1) use this option as a threshold value below which a capacitor will not be output). The default value for cthresh is 10 femtofarads.

-p path
Normally, the path to search for .ext files is determined by looking for path commands in first ~cad/lib/magic/sys/.magic, then ~/.magic, then .magic in the current directory. If -p is specified, the colon-separated list of directories specified by path is used instead. Each of these directories is searched in turn for the .ext files in a design.

-r rthresh
Set the resistance threshold to rthresh ohms. Similar in function to -c, but for resistances. The default value for rthresh is 10 ohms.

-s sym=value
It’s possible to use special attributes attached to transistor gates to control the length and width of transistors explicitly, rather than allowing them to be determined by the extractor. These attributes are of the form ext:w=width^ or ext:l=length^, where width or length can either be numeric, or textual. (The trailing ``^’’ indicates that these are transistor gate attributes). If textual, they are treated as symbols which can be assigned a numeric value at the time ext2sim is run. The -s flag is used to assign numeric values to symbols. If a textual symbol appears in one of the above attributes, but isn’t given a numeric value via -s (or -S below), then it is ignored; otherwise, the transistor’s length or width is set to the numeric value defined for that symbol. (This option is not currently used by extcheck, but it is common to ext2sim (1) and other tools that are written using the extflat (3) library)

-C
Set the capacitance threshold to infinity. Because this avoids any internodal capacitance processing, all tools will run faster when this flag is given.

-R
Set the resistance threshold to infinity.

-S symfile
Each line in the file symfile is of the form sym=value, just like the argument to the -s flag above; the lines are interpreted in the same fashion. (This option is not currently used by extcheck, but it is common to ext2sim et. al.)

-T tech
Set the technology in the output .sim file to tech. This overrides any technology specified in the root .ext file.

SEE ALSO

ext2dlys (1), ext2sim (1), ext2spice (1), magic (1), rsim (1), sim2spice (1), ext (5), sim (5)

AUTHOR

Walter Scott

BUGS

The -s mechanism is incomplete; it should allow quantities other than transistor lengths and widths to be specified.