Aarthi Nadarajan Interns – Basic Intro

 Language “e”  The ‘e’ Language has constructs necessary for verification automation  Specman Elite is the tool from Verisity (now Cadence) that simulates ‘e’ code stand-alone or also with HDL simulator

 High Extensibility  All common procedural actions  No complex pointer arithmetic  Automated memory management  Predefined data structures

What are structs What are units Code Structure Basic ‘e’ Language Interns – Basic Intro

 Structs are dynamic objects and created on the fly when you want to use it and are usually destroyed by garbage collection mechanism.  Units are static objects which stay alive from start to end. They are generated at simulation zero time.

PurposeSyntax Code delimitation Inline comments -- VHDL style // Verilog Style Code block {... ;... ;... ; }; Names start with letter include only letters, numbers, and underscores Hierarchy path (between structs and their members). (dot)

Example: struct my_struct { }; struct MY_STRUCT { }; The e language is case sensitive. Both for predefined syntax keywords and user-defined names. struct is a keyword. All syntax keywords are lower-case. The name my_struct is different from the name MY_STRUCT. Example Code

Interns – Basic Intro

NameDescriptionExample boolBoolean value: TRUE or FALSEpacket_valid: bool; intInteger, default 32 bitslength: int; addr: int(bits: 24); uintUnsigned integer, default 32 bitsaddr: uint(bits: 8); bit1-bit unsigned integervalid: bit; byte8-bit unsigned integerdata: byte; time64-bit unsigned integerdelay: time; stringString of ASCII charactersprompt: string; listResizable, ordered arraypayload: list of byte;

Syntax : type enum-type: [name1[=exp],...] [(bits|bytes: width-exp)]; Example: type opcode: [ADD, SUB]; Enumerated type statement. Default first enum value is 0. Subsequent enum values increment by 1. This internal value is used for comparisons (with strong type matching maintained). Values can be explicitly assigned with the syntax: type opcode: [ADD = 4, SUB = 6]; By default the new enumerated type is 32 bits, but it can be sized according to the number of bits required. type direction: [READ, WRITE](bits: 1);

Syntax : import file-name, … | ( file-name, … ); Example: <' import my_packet, my_port;... '> Specman e files are called modules. To reference statements or struct members that are declared in other modules, use the import statement so that Specman loads those modules first. The import statement must be before any other statements.

 Lists List types hold ordered collections of data elements where each data element conforms to the same type. Items in a list can be indexed with the subscript operator [ ], by placing a non-negative integer expression in the brackets. List indexes start at zero. You can select an item from a list by specifying its index. Lists are dynamically resizable. Lists contain many predefined methods. Lists are defined by using the list of keyword in a variable or a field definition.

e methods are similar to C functions, Verilog tasks, and VHDL processes. An e method is an operational procedure containing actions that define its behavior. Syntax: method_name([arg: type, …])[:return_type] is { action; };

Methods can: Contain actions (procedural code). Declare and use local variables. Have zero to fourteen input arguments/parameters. Optionally return a value Optionally consume time if declared to be a “Time-Consuming Method(TCM)” What values can be read or written inside a method? Locally declared variables within the method Fields within the local struct’ Arguments (parameters) and return value of the method Fields in other structs using path notation

Procedural flow control elements: 1. if then else Syntax if bool-exp [then] {action;...} [else if bool-exp [then] {action;...}] [else {action;...}] 2. case labeled-case-item Syntax case case-exp {labeled-case-item;. [default: {default-action;.}]} 3. case bool-case-item Syntax case {bool-case-item;... [default {default-action;...}]}

1. while Syntax while bool-exp [do] {action;...} 2. repeat until Syntax repeat {action;...} until bool-exp 3. for each in Syntax for each [type] [(item-name)] [using index (index-name)] in [reverse] list-exp [do] {action;.} 4. for from to Syntax for var-name from from-exp [down] to to-exp [step step-exp] [do] {action;.} 5. for Syntax for {initial-action; bool-exp; step-action} [do] {action;...}

 Constraints are directives that influence the behavior of the Specman test generator. They are declared within a struct and influence the generation of values for data items within the struct and its subtree. 1. Hard Constraints 2. Soft Constraints

 Constraints can be defined in many ways:. By defining a range of legal values in the field or variable declaration. By defining a list size in the list declaration. By using one of the keep construct variations within a struct definition. By using a gen...keeping action within a method

keep Syntax keep constraint-bool-exp keep for each Syntax keep for each [(item-name)] [using [index (index- name)] [prev (prev-name)]] in gen-item {constraint-bool-exp | nested-for-each;.}

 keep soft Syntax keep soft constraint-bool-exp  keep soft - select Syntax keep soft gen-item==select {weight: value;.}

 There are two ways to implement object-oriented inheritance in e: like inheritance or when inheritance Like inheritance is the classical, single inheritance familiar to users of all object-oriented languages and is specified with the like clause in new struct definitions. When inheritance is a concept unique to e and is specified by defining subtypes with when struct members. When inheritance provides the following advantages compared to like inheritance: -Ability to have explicit reference to the when fields -Ability to have multiple, orthogonal subtypes -Ability to extend the struct later

 A TCM is a time-consuming method that is distinguished from a regular method by the presence and can use time-consuming actions such as sync and wait. Invoking TCMs: 1.tcm() Syntax [[struct-exp].]method-name([parameter-list]) Description -Calling a TCM -You can call a TCM only from another TCM.

2.start tcm()  Syntax start [[struct-exp].]method-name([parameter-list])  Description A start action can be used within another method, either a TCM or a regular method. A started TCM begins execution either when its sampling event occurs or immediately, if the sampling event has already occurred for the current Specman tick. A started TCM runs in parallel with the TCM that started it on a separate thread. Notes. A TCM that has a return value cannot be started with a start action.. You cannot start a TCM before the run phase begins or after the check phase begins.

 Packing performs concatenation of scalars, strings, list elements, or struct fields in the order that you specify Unpacking performs the reverse operation, splitting a single expression into multiple expressions. 1.pack() Syntax pack(option:pack option, item: exp,.): list of bit Parameters packing.high Places the least significant bit of the last physical field declared or the highest list item at index [0] in the resulting list of bit. packing.low Places the least significant bit of the first physical field declared or lowest list item at index [0] in the resulting list of bit.