Class: Idl::AryElementAssignmentAst

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

Overview

represents an array element assignement

for example:

X[rs1] = XLEN'd0

Instance Method Summary collapse

Constructor Details

#initialize(input, interval, lhs, idx, rhs) ⇒ AryElementAssignmentAst

Returns a new instance of AryElementAssignmentAst.



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# File 'lib/idl/ast.rb', line 1748

def initialize(input, interval, lhs, idx, rhs)
  super(input, interval, [lhs, idx, rhs])
end

Instance Method Details

#execute(symtab) ⇒ void

This method returns an undefined value.

“execute” the statement by updating the variables in the symbol table

Parameters:

  • symtab (SymbolTable) —

    The symbol table for the context

Raises:

  • ValueError if some part of the statement cannot be executed at compile time



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# File 'lib/idl/ast.rb', line 1787

def execute(symtab)
  lhs_type = lhs.type(symtab)
  return if lhs_type.global?

  case lhs_type.kind
  when :array
    idx_value = idx.value(symtab)
    lhs_value = lhs.value(symtab)
    value_result = value_try do
      lhs_value[idx_value] = rhs.value(symtab)
    end
    value_else(value_result) do
      lhs_value[idx_value] = nil
      value_error "right-hand side of array element assignment is unknown"
    end
  when :bits
    var = symtab.get(lhs.text_value)
    value_result = value_try do
      v = rhs.value(symtab)
      var.value = (lhs.value(symtab) & ~0) | ((v & 1) << idx.value(symtab))
    end
    value_else(value_result) do
      var.value = nil
    end
  else
    internal_error "unexpected type for array element assignment"
  end
end

#execute_unknown(symtab) ⇒ void

This method returns an undefined value.

“execute” the statement, forcing any variable assignments to an unknown state This is used down unknown conditional paths.

Parameters:

  • symtab (SymbolTable) —

    The symbol table for the context

Raises:

  • ValueError if some part of the statement cannot be executed at compile time



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# File 'lib/idl/ast.rb', line 1817

def execute_unknown(symtab)
  case lhs.type(symtab).kind
  when :array
    lhs_value = lhs.value(symtab)
    value_result = value_try do
      idx_value = idx.value(symtab)
      value_result = value_try do
        lhs_value[idx_value] = rhs.value(symtab)
      end
      value_else(value_result) do
        lhs_value[idx_value] = nil
        value_error "right-hand side of array element assignment is unknown"
      end
    end
    value_else(value_result) do
      # the idx isn't known; the entire array must become unknown
      lhs_value.map! { |_v| nil }
    end
  when :bits
    var = symtab.get(lhs.text_value)
    value_result = value_try do
      v = rhs.value(symtab)
      var.value = (lhs.value & ~0) | ((v & 1) << idx.value(symtab))
    end
    value_else(value_result) do
      var.value = nil
    end
  else
    internal_error "unexpected type for array element assignment"
  end
end

#idx ⇒ Object 



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# File 'lib/idl/ast.rb', line 1745

def idx = @children[1]

#lhs ⇒ Object 



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# File 'lib/idl/ast.rb', line 1744

def lhs = @children[0]

#rhs ⇒ Object 



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# File 'lib/idl/ast.rb', line 1746

def rhs = @children[2]

#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 1850

def to_idl = "#{lhs.to_idl}[#{idx.to_idl}] = #{rhs.to_idl}"

#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 1753

def type_check(symtab)
  lhs.type_check(symtab)
  unless [:array, :bits].include?(lhs.type(symtab).kind)
    type_error "#{lhs.text_value} must be an array or an integral type"
  end
  type_errpr "Assigning to a constant" if lhs.type(symtab).const?

  idx.type_check(symtab)

  type_error "Index must be integral" unless idx.type(symtab).integral?

  value_result = value_try do
    idx_value = idx.value(symtab)
    type_error "Array index (#{idx.text_value} = #{idx_value}) out of range (< #{var.type(symtab).width})" if idx_value >= lhs.type(symtab).width
  end
  # OK, doesn't need to be known

  rhs.type_check(symtab)

  case lhs.type(symtab).kind
  when :array
    unless rhs.type(symtab).convertable_to?(lhs.type(symtab).sub_type)
      type_error "Incompatible type in array assignment"
    end
  when :bits
    unless rhs.type(symtab).convertable_to?(Bits1Type)
      type_error "Incompatible type in integer slice assignement"
    end
  else
    internal_error "Unexpected type on array element assignment"
  end
end