Module: HDLRuby::High::Hmux

Included in:
HBlock, Scope, SystemT
Defined in:
lib/HDLRuby/hruby_high.rb

Overview

Module providing methods for declaring select expressions.

Instance Method Summary collapse

Instance Method Details

#mux(select, *choices) ⇒ Object

Creates an operator selecting from +select+ one of the +choices+.

NOTE: * +choices+ can either be a list of arguments or an array. If +choices+ has only two entries (and it is not a hash), +value+ will be converted to a boolean. * The type of the select is computed as the largest no integer-constant choice. If only constant integer choices, use the largest type of them.



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# File 'lib/HDLRuby/hruby_high.rb', line 238

def mux(select,*choices)
    select = select ? 1 : 0 if [true,false,nil].include?(select)
    if select.respond_to?(:to_i) then
      # The mux can be evaluate straight away. Do metaprograming.
      return choices[select.to_i]
    end
    # Process the choices.
    choices = choices.flatten(1) if choices.size == 1
    choices.map! { |choice| choice.to_expr }
    # Compute the type of the select as the largest no 
    # integer-constant type.
    # If only such constants, use the largest type of them.
    type = choices.reduce(Bit) do |type,choice|
        unless choice.is_a?(Value) && choice.type == Integer then
            type.width >= choice.type.width ? type : choice.type
        else
            type
        end
    end
    unless type then
        type = choices.reduce(Bit) do |type,choice|
            type.width >= choice.type.width ? type : choice.type
        end
    end
    # Generate the select expression.
    return Select.new(type,"?",select.to_expr,*choices)
end