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> [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> [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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