Class: Idl::AryRangeAssignmentAst

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

Overview

represents an array range assignment

for example:

vec[8:0] = 8'd0

Instance Method Summary collapse

Constructor Details

#initialize(input, interval, variable, msb, lsb, write_value) ⇒ AryRangeAssignmentAst

Returns a new instance of AryRangeAssignmentAst.



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# File 'lib/idl/ast.rb', line 1876

def initialize(input, interval, variable, msb, lsb, write_value)
  super(input, interval, [variable, msb, lsb, write_value])
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 1913

def execute(symtab)
  return if variable.type(symtab).global?

  value_result = value_try do
    var_val = variable.value(symtab)

    msb_val = msb.value(symtab)
    lsb_val = lsb.value(symtab)

    type_error "MSB (#{msb_val}) is <= LSB (#{lsb_val})" if msb_val <= lsb_val

    rval_val = write_value.value(symtab)

    mask = ((1 << msb_val) - 1) << lsb_val

    var_val &= ~mask

    var_val | ((rval_val << lsb_val) & mask)
    symtab.add(variable.name, Var.new(variable.name, variable.type(symtab), var_val))
    :ok
  end
  value_else(value_result) do
    symtab.add(variable.name, Var.new(variable.name, variable.type(symtab)))
    value_error "Either the range or right-hand side of an array range assignment is unknown"
  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 1941

def execute_unknown(symtab)
  symtab.add(variable.name, Var.new(variable.name, variable.type(symtab)))
end

#lsb ⇒ Object 



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# File 'lib/idl/ast.rb', line 1873

def lsb = @children[2]

#msb ⇒ Object 



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# File 'lib/idl/ast.rb', line 1872

def msb = @children[1]

#rhs ⇒ Object 



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# File 'lib/idl/ast.rb', line 1908

def rhs
  write_value
end

#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 1946

def to_idl = "#{variable.to_idl}[#{msb.to_idl}:#{lsb.to_idl}] = #{write_value.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 1881

def type_check(symtab)
  variable.type_check(symtab)
  type_error "#{variable.text_value} must be integral" unless variable.type(symtab).kind == :bits
  type_error "Assigning to a constant" if variable.type(symtab).const?

  msb.type_check(symtab)
  lsb.type_check(symtab)

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

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

    type_error "MSB must be > LSB" unless msb_value > lsb_value
    type_error "MSB is out of range" if msb_value >= variable.type(symtab).width
  end
  # OK, don't have to know the value

  write_value.type_check(symtab)

  unless write_value.type(symtab).integral?
    type_error "Incompatible type in range assignment"
  end
end

#variable ⇒ Object 



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# File 'lib/idl/ast.rb', line 1871

def variable = @children[0]

#write_value ⇒ Object 



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# File 'lib/idl/ast.rb', line 1874

def write_value = @children[3]