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Virtuoso Schematic Composer User Guide

Understanding Connectivity and Naming Conventions

Analyzing Net Expression Property Names and Evaluated Names

A designer who uses inherited connections during the many phases of the design process can take advantage of the analyzing commands. You can find the net expression property names that are available for setting on the selected instances as well as investigate the evaluated names produced by all net expressions below the selected instances.

The analysis commands might be useful for the following tasks:

Block authoring

Module instantiation

Chip assembly

Debugging

For details, see the Inherited Connections Flow Guide.

Summary of Naming Conventions

The following tables detail naming conventions.

Reserved Characters for Wire, Net, and Pin Names on page 123

Reserved Characters for Instances on page 123

Illegal Characters in Wire and Net Names on page 123

Illegal Characters in Instance Names on page 123

Syntax Conventions for Wire, Net, and Pin Names on page 124

Syntax Conventions for Instances on page 125

Expanded Names for Wires, Nets, and Pins on page 125

Expanded Names for Instances on page 126

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Table 2-1 Reserved Characters for Wire, Net, and Pin Names

Character

Symbol

Description

Example

 

 

 

 

 

 

comma

,

Separates the elements of a wire name

A,B<0:1>,C

 

angle brackets

< >

Enclose expressions for multiple-bit

A<0:3>,

 

 

 

wires; used for iterators (prefix repeat

<*2>B,<12>

 

 

 

operator) and bus taps

 

 

parentheses

( )

Enclose related multiple-bit wires within

A<(0:2)*2>

 

 

 

an expression

 

 

asterisk

*

Is used in the graphic screen to

A<(0:2)*2>

 

 

 

highlight net expression labels is not

 

 

 

 

part of the net expression

 

 

colon

:

Separates a range of numbers within

A<0:2>

 

 

 

an expression

 

 

exclamation point

!

Global signal for a power supply

vdd!, gnd!

 

 

 

 

Table 2-2 Reserved Characters for Instances

 

 

 

 

 

 

 

Character

Symbol

Description

Example

 

 

 

 

 

 

angle brackets

< >

Enclose a range of numbers

A<0>

 

colon

:

Separates a range of numbers

A<1:3>

 

 

 

expressed by a starting and ending

 

 

 

 

number

 

 

 

 

 

 

 

Table 2-3 Illegal Characters in Wire and Net Names

Character Symbol

forward slash

/

 

 

Table 2-4 Illegal Characters in Instance Names

Character Symbol

comma ,

parentheses

( )

asterisk *

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Table 2-4 Illegal Characters in Instance Names

colon

:

 

forward slash

/

 

 

 

Table 2-5 Syntax Conventions for Wire, Net, and Pin Names

 

 

Name

Description

 

 

baseName

A string of printable ASCII characters that does not include reserved

 

characters.

 

NET, R, C

nameTerm

A baseName optionally followed by a vector expression enclosed in angle

 

brackets.

 

A nameTerm can also be a name expression enclosed in parentheses.

 

nameTerm ::= baseName [ < vectExpr > ] |

 

( nameExpr )

nameExpr

A string consisting of a nameTerm, optionally prefixed with the<*n>

 

construct. The <*n> construct is also referred to as a prefix repeat

 

operator, which means that the nameTerm is to be repeated n times.

 

Name expressions can be concatenated to form a comma-separated list.

 

nameExpr ::= [ < *n > ] nameTerm

 

{ , nameExpr }

vectTerm

A single number or a range of numbers. The range can be expressed by a

 

starting, ending, and increment number, separated by colons.

 

A vectTerm can also be a vector expression enclosed in parentheses. In

 

this case, the innermost term is expanded first, and then therepeat

 

operator repeats the entire expanded term enclosed in parentheses.

 

vectTerm ::= n[ : n[ : n] ] |

 

( vectExpr )

vectExpr

A single or repeated vectTerm. The optional <*n> suffix on avectTerm

is called a suffix repeat operator and indicates n repetitions of each bit of the vectTerm. The value of n must be greater than zero.

Vector expressions can be concatenated to form a comma-separated list.

vectExpr ::= vectTerm [ *n ] { , vectExpr }

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Table 2-6 Syntax Conventions for Instances

Name Description

baseName A string of printable ASCII characters that does not include reserved characters.

I0, R, C

instName Scalar and iterated instance names must be unique. A scalar name cannot imply more than one member. An iterated instance name must imply the same number of members as iterations.

instName ::= baseName [ < n [ : n ] > ]

where n is a positive integer less than 16,375.

Table 2-7 Expanded Names for Wires, Nets, and Pins

Sample Name

Members

Expanded Form

 

 

 

clk

1

clk

data<2>

1

data<2>

<*1>base

1

base

<*2>term

2

term,term

<*2>(a,b),c

5

a,b,a,b,c

<*2>(a,<*2>b)

6

a,b,b,a,b,b

b<0:2>

3

b<0,1,2> or b<0>,b<1>,b<2>

b<0:2:1>

3

b<0,1,2>

b<3:0:2>

2

b<3,1>

b<0:2*2>

6

b<0,0,1,1,2,2,>

b<(0:2)*2>

6

b<0,1,2,0,1,2>

b<0,2*2>

3

b<0,2,2>

b<(0,2)*2>

4

b<0,2,0,2>

b<0,1:3:4*1,2:2>

3

b<0,1,2>

b<0:1,2:2>

3

b<0,1,2>

 

 

 

Note: You can use up to 1,024 characters for a name, but the editor ignores any blank or tab characters found before or after a name.

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To determine the nth member name, use a zero-based counting method to find thenth element in the expanded form. For example,

Member zero of <*2>(a,<*2>b) is a

Member one of <*2>(a,<*2>b) is b

Member two of <*2>(a,<*2>b) is b, and so on

If the name contains a vector expression, such as b<0:1,2:2>, then

Member zero in this case is called b<0>

Member one in this case is called b<1>

Member two in this case is called b<2>

Table 2-8 Expanded Names for Instances

Name

Members

Expanded Form

 

 

 

H10

1

H10

J20<0:1>

2

J20<0>, J20<1>

K30<2:1>

2

K30<2>, K30<1>

 

 

 

Note: You can use up to 1,024 characters for a name, but the editor ignores any blank or tab characters found before or after a name.

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