Characteristics of OASIS Output From Xic

The basic OASIS file generated by Xic has the characteristics listed below.

• By default, all strings are saved locally as strings, i.e., no indirection is used, so there are no <name> records. This can be changed with the OasWriteNameTab variable which is connected to Use string tables check boxes in the Format Conversion and Export Control panels.

• By default, no REPETITION records are generated for <geometry> records. If the OasWriteRep variable or the corresponding check box is set, REPETITION record types may be generated. This option attempts to recognize arrays of identical objects when writing OASIS files.

• By default, appropriate three and four-sided polygons will be written as TRAPEZOID or CTRAPEZOID records, however this can be disabled with the OasWriteNoTrapezoids variable.

• By default, wires (paths) will retain that data type. However, rectangular two-vertex paths will be converted to a more compact rectangle representation if OasWriteWireToBox is set.

• The following record types are not generated by Xic: CIRCLE, XNAME, XELEMENT, XGEOMETRY.

• When writing OASIS files with StripForExport set, i.e., writing physical data only, and when using string tables, the offset table is placed in the END record. With StripForExport not set, in general we write two sequential OASIS databases into the file, the first for physical data, the second for electrical. This is a Xic-specific extension. In this case, string tables are used in the physical part only, and the offset table is placed in the START record. PAD records are added to avoid overwriting data since this is a non-sequential operation. In all cases, strict-mode tables are used.

  Note: If a design contains physical data only, the electrical records are absent, so that the file becomes conventional. Even if electrical records are present, the reader will probably ignore them (as does anuvad-0.2). However, when exporting physical data, for portability StripForExport should always be set.

  The string tables themselves are written just ahead of the END record in all cases (when tables are used).

• OASIS files generated by Xic release 3.2.2 and later have a file property named ``XIC_SOURCE'', with no content. This identifies the file as originating from Xic or a derivative.

• All integer values are 32-bit limited, except for values that represent offsets into the file, which may be 64-bit.

• The OASIS format does not provide a native code to indicate a rounded-end wire. For wires that have rounded ends, i.e., that originated as GDSII PATHTYPE=1, the half-width extension is specified, and the PATH record is given an empty (info byte = 0x4) property named ``XIC_ROUNDED_END''.

• The OASIS format does not provide codes for TEXT element presentation. In Xic, these are used for on-screen labels, and are treated by Xic as any other database object, but they will not appear on the mask layout. Thus, at least for Xic internal use, TEXT presentation attributes are important. They are stored in a property applied to TEXT records named ``XIC_LABEL''. The XIC_LABEL property contains two unsigned integers. The first is the width of the label, in database units. The second is the label flags word used by Xic which specifies many presentation attributes. See C.2 for more information.

• OASIS text labels can contain only printable ASCII characters and the space character, thus some trickery is used to support multi-line labels. In OASIS files generated from Xic, the following non-printing characters are replaced with the indicated character sequence when encountered in label text:

  0xa (line feed)	`` \ n''
  0xd (carriage return)	`` \ r''
  0x9 (tab)	`` \ t''

  The OASIS reader will perform the reverse conversion, if the XIC_SOURCE property is found in the file, meaning that it was written by Xic.

• All other properties, which might be given to CELL or <geometry> records, are named
  ``XIC_PROPERTY'' and consist of concatenated number/string pairs. Xic uses properties indexed by a number, with string-type data, so that the XIC_PROPERTY consists of the list of properties as known to Xic for that cell or object.

There are several options in Xic that modify OASIS input/output. Many of these can be controlled by check boxes in the OASIS page in the Export Control and Format Conversion panels from the Convert Menu, which reflect the status of the variables (which can also be set with the !set command or equivalent).

Convert Menu - Input and ASCII Output
OasReadNoChecksum	Ignore checksum in OASIS input file
OasPrintNoWrap	Use one line per record in OASIS ASCII output
OasPrintOffset	Add file offsets to OASIS ASCII output
Convert Menu - Output
OasWriteCompressed	Compress records in OASIS output
OasWriteNameTab	Use string table referencing in OASIS output
OasWriteRep	Try to combine similar objects in OASIS output
OasWriteChecksum	Compute and add checksum to OASIS output
OasWriteNoTrapezoids	Don't convert polys to trapezoids
OasWriteWireToBox	Convert wires to boxes when possible
OasWriteNoGCDcheck	Don't look for common divisors in repetitions
OasWriteUseFastSort	Use faster but less effective sorting
OasWriteNoXicTextPrps	Don't write certain text properties