RE: [sv-bc] packed union net ?

From: Radosław Nawrot <Radoslaw.Nawrot@aldec.com.pl> Date: Mon Oct 13 2014 - 06:23:13 PDT · This archive was generated by hypermail 2.1.8 : Mon Oct 13 2014 - 06:24:12 PDT

And that's what I was thinking about when I was wondering about resolution
function  of 2-states built-in datatypes

  _____  

From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
Sent: Monday, October 13, 2014 3:20 PM
To: Radosław Nawrot; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

6.11.2 says, 

"When a 4-state value is automatically converted to a 2-state value, any
unknown or high-impedance bits shall be converted to zeros."

From: Radosław Nawrot [mailto:Radoslaw.Nawrot@aldec.com.pl] 
Sent: Monday, October 13, 2014 16:17
To: Bresticker, Shalom; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

Thanks I didn't found it in LRM , so I assume that it should be simple
resolution between 4 tate and 2- statre (i.e  Z into 0)

  _____  

From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
Sent: Monday, October 13, 2014 3:11 PM
To: Radosław Nawrot; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

If no resolution function is defined, then multiple drivers are not allowed.
It is true that in the case of no driver, you would still get a Z turning to
0.

From: Radosław Nawrot [mailto:Radoslaw.Nawrot@aldec.com.pl] 
Sent: Monday, October 13, 2014 16:09
To: Bresticker, Shalom; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

but resolution function is optional 

  _____  

From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
Sent: Monday, October 13, 2014 3:03 PM
To: Radosław Nawrot; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

In user-defined net types, the resolution method is user-defined. There is
no built-in resolution function. Maybe I am not understanding you.

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of Rados?aw
Nawrot
Sent: Monday, October 13, 2014 16:01
To: Bresticker, Shalom; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

Ok.
I'm just wondering : why isn't it allowed with the same resolution method as
in user-defined net types ?

Regards,
Radek

  _____  

From: Bresticker, Shalom [mailto:shalom.bresticker@intel.com] 
Sent: Monday, October 13, 2014 2:48 PM
To: Radosław Nawrot; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

Thanks.

It was deliberate for wires not to be allowed 2-state built-in data types,
because such drivers can have multiple or no drivers, resulting in X or Z
states, which 2-state data types cannot express.

Regards,

Shalom

From: Radosław Nawrot [mailto:Radoslaw.Nawrot@aldec.com.pl] 
Sent: Monday, October 13, 2014 15:42
To: Bresticker, Shalom; 'SV-BC'
Subject: RE: [sv-bc] packed union net ?

BNF allow it :

net_declaration12 ::= // from A.2.1.3

net_type [ drive_strength | charge_strength ] [ vectored | scalared ]

data_type_or_implicit [ delay3 ] list_of_net_decl_assignments ;

data_type_or_implicit ::=

data_type

| implicit_data_type

data_type ::=

integer_vector_type [ signing ] { packed_dimension }

| integer_atom_type [ signing ]

| non_integer_type

| struct_union [ packed [ signing ] ] { struct_union_member {
struct_union_member } }

{ packed_dimension }13

| enum [ enum_base_type ] { enum_name_declaration { , enum_name_declaration
} }

{ packed_dimension }

| string

| chandle

| virtual [ interface ] interface_identifier [ parameter_value_assignment ]
[ . modport_identifier ]

| [ class_scope | package_scope ] type_identifier { packed_dimension }

| class_type

| event

| ps_covergroup_identifier

| type_reference14

Additionally  (As a workaround ) user can define own nettype:

6.6.7 (User-defined nettypes):

Certain restrictions apply to the data type of a net with a user-defined
nettype. A valid data type shall be

one of the following:

a) A 4-state integral type, including a packed array, packed structure or
union.

b) A 2-state integral type, including a packed array, packed structure or
union with 2-state data type

members.

BTW : Is it inconsequence that LRM allows 2-state user-defined nets but
disallows (according to 6.7.1 citatum ) 2-state build-in net ?

Radek

  _____  

From: owner-sv-bc@eda.org [mailto:owner-sv-bc@eda.org] On Behalf Of
Bresticker, Shalom
Sent: Sunday, October 12, 2014 3:07 PM
To: 'SV-BC'
Subject: [sv-bc] packed union net ?

Can a net be a packed union ?

6.7.1 says,

Certain restrictions apply to the data type of a net. A valid data type for
a net shall be one of the following:

a) A 4-state integral type, including a packed array or packed structure.

b) A fixed-size unpacked array or unpacked structure, where each element has
a valid data type for a net.

However, 6.11.1 defines packed unions as integral types:

"The term integral is used throughout this standard to refer to the data
types that can represent a single basic

integer data type, packed array, packed structure, packed union, enum
variable, or time variable."

Thanks,

Shalom

Shalom Bresticker 
Communications & Storage Infrastructure Group Design Automation

Intel Jerusalem, Israel 
+972  2 589 6582 (office) 
+972 54 721 1033 (cell) 
http://www.linkedin.com/in/shalombresticker 

The devil is in the details.

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