Port Expressions/Conversions

• You Used to Have to Provide Your Own Conversion Functions
• U1:AND port map ( A => bit( true ), boolean( B ) => my_var

Pure vs Impure Functions

• [pure|impure] function identifier

pure

Returns the Same Value When Called with the Same Actual Parameters

impure

May Return Different Values. Update Objects Outside of Their Scope.

Foreign SubProgram

• VHDL Not Used for Implimentation
• example:
• function foobar return integer;
  • attribute FOREIGN of foobar:function is "Some Useful Implimentation String";

File I/O

• procedure FILE_OPEN ( file f : ftype;
  • External_Name: in string;
  • Open_Kind : in File_Open_Kind := READ_MODE );

• procedure FILE_OPEN ( Status : out FILE_OPEN_STATUS;
  • file f : ftype;
  • External_Name: in string;
  • Open_Kind : in File_Open_Kind := READ_MODE );

• File_Open_Kind Values:
  • READ_MODE
  • WRITE_MODE
  • APPEND_MODE
• Status Values:

  OPEN_OK

  File Opened Successfully

  STATUS_ERROR

  File Object Already has an External File Associated With it

  NAME_ERROR

  External File Does Not Exist

  MODE_ERROR

  External FIle Can Not Open With Requested File_Open_Kind

• procedure FILE_CLOSE ( file f : ftype )

• procedure READ ( file f : ftype; Value : out vtype; Length : out Natural );
• --Returns length of 'value'

• type data_file is file of integer;
• file f1 : data_file;
• --No Implicit FILE_OPEN
• file f1 : data_file is "test.dat";
• --Implicit FILE_OPEN w/ READ_MODE Default
• file f1 : data_file open WRITE_MODE is "test.dat";
• --Implicit FILE_OPEN w/ WRITE_MODE

• Files can be Passed to SubPrograms as Parameters

Shift Operators

sll

srl

shift left/right logical. Filled with T'left of Base Type

sla

sra

shift left/right arithmetic. Filled with T(T'right)

rol

ror

rotate left/right logical.

Signal Assignment

• [label:] target <= [transport|[reject time] inertial] waveform;
• waveform : waveform_element {,waveform_element } | unaffected
• When Conditions are Met There is no Change to Target Signal Drivers.

Extended Identifiers

Now Supports ISO-8859-I Charater Set for European Languages

Basic Identifiers

consists of letters, digits & underscores

Extended Identifiers

Consist of Any Characters. Examples

• \port map my entity\ --distinct
• \PORT MAp my enTITy\ -- identifiers
• \I like to use \\ back slash\

XNOR Operator

• A <= B xnor C;

Shared Variables

• Previously Limited to Immediate Enclosing Process
• New Prefix Keyword Shared
• When Shared, Permitted in Declarative Regions for:
  • Block
  • Entity
  • Architecture
  • Package
• Example:
• Shared Variable pi : real := 3.14 ;

Uniform End/Is Syntax

Additions are in [] braces

• Uniform Is Syntax
  • Block [ is ]
  • Component comp_name [ is ]
• New, Uniform Ending Syntax:
  • end component [ comp_name ];
  • end [ architecture ] arch_name;
  • end [ entity ] entity_name;
  • end [ package body ] pkg_name;
  • end case [ case_label ];
  • end if [ if_label ];
  • end [ record ] record_name;
  • end [ function ] func_name;
  • end [ procedure ] proc_name;

Attributes

t'ASCENDING

Returns True if scalar type t has ascending range

a'ASCENDING(n)

Returns True nth index of array type a has ascending range

t'IMAGE(x)

Returns string representation of the value of x of scalar type t

s'DRIVING

Returns False if no Active Drivers in Current Process

e'INSTANCE_NAME

Returns string describing hierarchical path to entity e including instantiated architectures

e'PATH_NAME

Returns string describing hierarchical path to entity e excluding architectures

Assert

In Order to Unconditionally Output a Message You Used to..

• assert false .. "unconditional message"
• Has Been Replaced by..
• report "unconditional message.."