SDF Annotator Guide

Using the SDF File

The SDF file supports hierarchical delay annotation. A design hierarchy might include several different application-specific integrated circuits (ASICs), including cells or blocks within

ASICs. Each design hierarchy has its own SDF file, as shown in Figure 3-1 .

Figure 3-1 Multiple SDF Files in a Hierarchical Design

SDF File Conventions

This section describes identifiers, character use, operators, and common expressions in SDF files.

Using Identifiers

Identifiers are names for ports or nets, depending on the syntax. Identifiers can have up to 1024 alphanumeric characters. Special characters are permitted if the escape character precedes the special character. Spaces are not allowed in identifiers. For more information about character use in SDF files, see “Using Characters” on page 32.

You can specify hierarchical identifiers by placing the hierarchy divider character (. or /) in the identifier name.

Bit specifications can be placed at the end of identifiers with no spaces between the bit specifications and the identifier. Bit specifications are specified in square braces ([ ]). If the bit spec is a range, use a colon to separate the range, as shown in the following examples:

Edge identifiers are specified with the following names:

SDF Annotator Guide

Using the SDF File

Examples of Correct IDENTIFIERs

AMUX\+BMUX Cache_Row_\#4

mem_array\[0\:1023\]\(0\:15\)

//From a language where square brackets indicate arrays // parentheses indicate bit specs

pipe4\-done\&enb[3]

// Unescaped square brackets is a bit spec

Examples of Incorrect IDENTIFIERs

\AMUX+BMUX

// Do not use Verilog style name escaping

PHASE\ LOCK\ DONE

// Spaces cannot be escaped

Ctl_Brk\

// Do not use carriage return

MEM[4:16]_BRK\+IDLE

// Do not include bit specs within identifiers

Using Characters

The following table describes the characters you can use in the SDF file.

SDF Annotator Guide

Using the SDF File

Note: The escape character (\) must precede a special character in a port or net identifier, which enables you to use special characters in port or net identifier names. If you use an escape character preceding a hierarchy divider character (. or /), the characters no longer divide the hierarchy.

Operator Precedence

Figure 3-2 shows the order of precedence for SDF operators. Operators shown on the same row have the same precedence.

OVI SDF Specification Tool Compatibility

This section shows the keywords that Verilog-XL and Verifault-XL uses. Each tool can read an SDF file with all the OVI SDF Standard keyword constructs, but each tool uses a different subset of the OVI SDF Standard keyword constructs. Because a subset of OVI standard keywords apply to some tools but not others, some of the OVI keywords are ignored by the SDF Annnotator. You do not receive error messages on ignored, syntactically correct OVI standard keyword constructs. The OVI SDF Standard keywords are described in “SDF File Keyword Constructs” on page 38.

OVI Standard SDF Keywords

Figure 3-3 shows the keywords that are supported by the OVI SDF Specification, Version 3.0.

Figure 3-3 OVI Standard 3.0 SDF Keywords

(DELAYFILE (SDFVERSION ...) (DESIGN ...) (DATE ...) (VENDOR ...) (PROGRAM ...) (VERSION ...) (DIVIDER ...) (VOLTAGE ...) (PROCESS ...) (TEMPERATURE ...) (TIMESCALE ...)