Transcript File
INTRODUCING SPECMAN
Aarthi Nadarajan Interns – Basic Intro
WHAT IS SPECMAN ?
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
‘E’ AS A PROGRAMMING LANGUAGE
High Extensibility All common procedural actions No complex pointer arithmetic Automated memory management Predefined data structures
A SAMPLE VERIFICATION ENVIRONMENT
GETTING STARTED
What are structs What are units Code Structure Basic ‘e’ Language Interns – Basic Intro
WHAT ARE STRUCTS AND UNITS ?
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.
CODE STRUCTURE
Purpose
Code delimitation Inline comments Code block Names Hierarchy path (between structs and their members)
Syntax
<' '>
--
VHDL style
//
Verilog Style {... ; ... ; ... ; }; start with letter include only letters, numbers, and underscores . (dot)
DEFINING UNITS AND STRUCTS
Example Code • The
e
language is case sensitive.
• Both for predefined syntax keywords and user-defined names.
Example:
struct
my_struct
{ }; struct
MY_STRUCT
{ }; struct
is a keyword. All syntax keywords are lower-case.
The name
my_struct
is different from the name
MY_STRUCT
.
BASICS OF ‘E’ LANGUAGE
Interns – Basic Intro
PREDEFINED TYPES
Name bool int uint bit byte time string list Description
Boolean value:
TRUE
or
FALSE
Integer, default 32 bits
Example
packet_valid:
bool;
length:
int;
addr:
int(bits:
24
);
Unsigned integer, default 32 bits 1-bit unsigned integer 8-bit unsigned integer 64-bit unsigned integer String of ASCII characters Resizable, ordered array addr:
uint(bits:
8
);
valid:
bit;
data:
byte;
delay:
time;
prompt:
string;
payload:
list of byte;
DEFINING ENUMERATED TYPES
Syntax : type enum-type: [name1[=exp], ...] [(bits|bytes: width-exp)]; Example: type opcode: [ADD, SUB]; • 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
);
• • 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];
IMPORT ‘E’ FILES
• 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
.
Syntax : import file-name , … | ( file-name, …
);
Example:
<' import
my_packet, my_port
; . . .
'>
LISTS IN ‘E’
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.
METHODS
•
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
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 CONTROL
Procedural flow control elements: 1.
if
then
else Syntax
if bool-exp [then] {
action
; ...} [ else if bool-exp {
action
; ...}] [
else
{
action
; ...}] [then] 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 ;...
}
]
}
PROCEDURAL LOOP CONSTRUCTS
1.
while Syntax
while bool-exp [
do
] {action ; ...
}
2.
repeat until Syntax
repeat {action ; ...
} until bool-exp 3.
for each in Syntax for each in
[ [
type
reverse
] ] [(
item-name list-exp
[
do
] )] [ using index (index-name) {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
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
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
DEFINING CONSTRAINTS
keep Syntax
keep constraint-bool-exp
keep for each Syntax keep for each
name) ] [ (item-name) ] [ [ prev (prev-name) ]]
in
gen-item {constraint-bool-exp
using
| [ index (index-
nested-for-each
; .
}
DEFINING CONSTRAINTS
keep soft Syntax
keep soft constraint-bool-exp
keep soft - select Syntax
keep soft gen-item==select {weight: value; .}
INHERITANCE
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
TIME CONSUMING METHODS
A TCM is a time-consuming method that is distinguished from a regular method by the presence of @event 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.
INVOKING TCM’S
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 AND UNPACKING
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.