Syntax for Rounding Parameter Values

The Rounding definition comprises three parts: (paramName value keyword).

paramName

The name of the parameter whose value is to be rounded. Valid parameter names are

Those specified by the transistorWidthParamNames environment variable.
The width parameter name specified in the component type to which the cellview is assigned.

value

A floating point number. If the specified parameter is to be rounded, the value returned is a nonzero integer multiple of the value.

The default unit for this value is microns. To specify a different unit, use one of the identifiers listed in the table below.

Layout XL never rounds to zero. If the closest rounded value is zero, no rounding takes place.

keyword

Specifies the rounding method used. Allowed values are

round rounds to the nonzero integer multiple at or closest to the current value. If the rounded result is zero, Layout XL issues a warning and the original value is returned unchanged.
floor rounds to the nonzero integer multiple at or below the current value. If the rounded result is zero, Layout XL issues a warning and the original value is returned unchanged.
ceil rounds to the nonzero integer multiple at or above the current value. If the rounded result is large, Layout XL issues a warning inviting you to check the rounding value.

Using ceil or floor with a float value that is not an integer can produce unexpected results.

Use the following identifiers to specify the rounding unit.

Identifier	Denotes	Factor	Example
`f`	femto	10^-15	`0.05f`
`p`	pico	10^-12	`0.05p`
`n`	nano	10^-9	`0.05n`
`u` (the default)	micro	10^-6	`0.05u` (or `0.05`)
`m`	milli	10^-3	`0.05m`
`c`	centi	10^-2	`0.05c`
`k`	kilo	10³	`0.05k`
`M`	mega	10⁶	`0.05M`
`G`	giga	10⁹	`0.05G`