Class: Idl::AryRangeAccessAst

Inherits:
AstNode
  • Object
show all
Includes:
Rvalue
Defined in:
lib/idl/ast.rb

Instance Method Summary collapse

Constructor Details

#initialize(input, interval, var, msb, lsb) ⇒ AryRangeAccessAst

Returns a new instance of AryRangeAccessAst.



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# File 'lib/idl/ast.rb', line 1566

def initialize(input, interval, var, msb, lsb)
  super(input, interval, [var, msb, lsb])
end

Instance Method Details

#lsb ⇒ Object 



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# File 'lib/idl/ast.rb', line 1564

def lsb = @children[2]

#msb ⇒ Object 



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# File 'lib/idl/ast.rb', line 1563

def msb = @children[1]

#to_idl ⇒ String

Return valid IDL representation of the node (and its subtree)

Returns:

  • (String) —

    IDL code for the node



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# File 'lib/idl/ast.rb', line 1613

def to_idl = "#{var.to_idl}[#{msb.to_idl}:#{lsb.to_idl}]"

#type(symtab) ⇒ Type

Given a specific symbol table, return the type of this node.

Should not be called until #type_check is called with the same arguments

Parameters:

Returns:

  • (Type) —

    The type of the node

Raises:



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# File 'lib/idl/ast.rb', line 1595

def type(symtab)
  value_result = value_try do
    msb_value = msb.value(symtab)
    lsb_value = lsb.value(symtab)
    range_size = msb_value - lsb_value + 1
    return Type.new(:bits, width: range_size)
  end
  # don't know the width at compile time....assume the worst
  value_else(value_result) { var.type(symtab) }
end

#type_check(symtab) ⇒ void

This method returns an undefined value.

type check this node and all children

Calls to #type and/or #value may depend on type_check being called first with the same symtab. If not, those functions may raise an AstNode::InternalError

Parameters:

Raises:



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# File 'lib/idl/ast.rb', line 1571

def type_check(symtab)
  var.type_check(symtab)
  msb.type_check(symtab)
  lsb.type_check(symtab)

  type_error "Range operator only defined for integral types (found #{var.type(symtab)})" unless var.type(symtab).integral?

  type_error "Range MSB must be an integral type" unless msb.type(symtab).integral?
  type_error "Range LSB must be an integral type" unless lsb.type(symtab).integral?

  value_result = value_try do
    msb_value = msb.value(symtab)
    lsb_value = lsb.value(symtab)

    if var.type(symtab).kind == :bits && msb_value >= var.type(symtab).width
      type_error "Range too large for bits (msb = #{msb_value}, range size = #{var.type(symtab).width})"
    end

    range_size = msb_value - lsb_value + 1
    type_error "zero/negative range (#{msb_value}:#{lsb_value})" if range_size <= 0
  end  # OK, don't have to know
end

#value(symtab) ⇒ Object

Return the compile-time-known value of the node



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# File 'lib/idl/ast.rb', line 1607

def value(symtab)
  mask = (1 << (msb.value(symtab) - lsb.value(symtab) + 1)) - 1
  (var.value(symtab) >> lsb.value(symtab)) & mask
end

#values(symtab) ⇒ Array<Integer>, ... Originally defined in module Rvalue

Return a complete list of possible compile-time-known values of the node, or raise a ValueError if the full list cannot be determined

For most AstNodes, this will just be a single-entry array

Parameters:

  • symtab (SymbolTable) —

    The context for the evaulation

Returns:

  • (Array<Integer>) —

    The complete list of compile-time-known values, when they are integral

  • (Array<Boolean>) —

    The complete list of compile-time-known values, when they are booleans

  • (AstNode::ValueError) —

    if the list of values is not knowable at compile time

#var ⇒ Object 



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# File 'lib/idl/ast.rb', line 1562

def var = @children[0]