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Expressions

  An ``expression'' combines signals using a collection of operators. These operators include:

• boolean operators (``and'', ``or'', ``not'' and ``xor''),
• conditional operators (``if-then-else'', ``case'' and ``switch'')
• arithmetic operators (``+'', ``-'', ``*'', ``/'', ``mod'', and shifts)
• comparison operators (``='', ``<'', ``>'', ``>='', ``<='')
• set operators (union, integer subrange and inclusion)
• vector operators (concatenation, subrange)
• conversion operations (integer to bit vector and vice versa)

Since signals are sequences of values, all of these operators apply to the elements of a sequence one-by-one. Thus, if

and is a binary operator, then

The following describes the various operators as they apply to individual values.

• Parentheses and precedence
• Integer constants
• Symbolic constants
• Boolean operators
• Conditional operators (``if'', ``case'' and ``switch'')
• Representing state machines using conditionals
• Arithmetic operators
• Comparison operators
• Set expressions
  • The set inclusion operator
  • Extension of operators to sets
  • Comprehension expressions