class Bliftax

A class that parses a BLIF file.

Constants

DECL_CLOCK
DECL_END
DECL_INPUTS
DECL_LATCH
DECL_MODEL
DECL_NAMES
DECL_OUTPUTS
EMPTY: Empty string for readability.
SPACE: One space for readability.
VERSION

Attributes

clocks[RW]

gates[RW]

inputs[RW]

latches[RW]

name[RW]

outputs[RW]

Public Class Methods

new(str = nil) click to toggle source

Initializes the object.

@param str [String] filename or text to parse.

# File lib/bliftax.rb, line 26
def initialize(str = nil)
  @latches = []
  @clocks = []
  @gates = []

  parse(str) unless str.nil?
end

Public Instance Methods

dup() click to toggle source

Duplicates this object.

@return [Bliftax] the deep copy of this object.

# File lib/bliftax.rb, line 124
def dup
  copy = Bliftax.new
  copy.name = @name.dup
  copy.inputs = @inputs.dup
  copy.outputs = @outputs.dup
  copy.latches = @latches.dup
  copy.clocks = @clocks.dup
  copy.gates = @gates.dup
  copy
end

parse(str) click to toggle source

Parses a BLIF file.

@param str [String] filename or the text to parse.

@return [Bliftax] the parsed BLIF file.

# File lib/bliftax.rb, line 39
def parse(str)
  fh = File.exist?(str) ? File.open(str) : StringIO.new(str)
  lines = read_continuous_lines(fh)

  lines.each_with_index do |line, i|
    (decl, *following) = line.split(SPACE)

    case decl
    when DECL_MODEL
      @name = following.first
    when DECL_INPUTS
      @inputs = following
    when DECL_OUTPUTS
      @outputs = following
    when DECL_NAMES
      @gates << parse_gate(following, lines, i + 1)
    when DECL_LATCH
      @latches << following
    when DECL_CLOCK
      @clocks << following
    when DECL_END
      break
    when /^[^\.]/
      next
    else
      fail "Unknown decl encountered: I don't understand `#{decl}' :("
    end
  end

  self
end

parse_gate(labels, lines, i) click to toggle source

Parse one gate from the input.

@param labels [Array<String>] labels of the inputs and output. @param lines [Array<String>] all the lines in the current BLIF file. @param i [Integer] index of in lines to start from.

@return [Gate] the gate that was parsed.

# File lib/bliftax.rb, line 78
def parse_gate(labels, lines, i)
  gate = Gate.new(labels)

  loop do
    # If no truth table exists, then that's all 0
    bit_str = lines[i].start_with?('.') ? Implicant::Bit::OFF : lines[i]
    gate.add_implicant(bit_str)

    i += 1

    break if lines[i].nil? || lines[i].empty? || lines[i].start_with?('.')
  end

  gate
end

to_blif() click to toggle source

Returns a string representation of this gate in BLIF format.

@return [String] this gate in BLIF format.

# File lib/bliftax.rb, line 97
  def to_blif
    in_labels = @inputs.join(SPACE)
    out_labels = @outputs.join(SPACE)
    str = <<-EOF
.model #{@name}
.inputs #{in_labels}
.outputs #{out_labels}
    EOF

    @gates.each do |gate|
      str << gate.to_blif
    end

    @latches.each do |l|
      str << format(".latch %s\n", l.join(SPACE))
    end

    @clocks.each do |c|
      str << format(".clock %s\n", c.join(SPACE))
    end

    str << ".end\n"
  end

Private Instance Methods

read_continuous_lines(fh) click to toggle source

Reads in the BLIF file creating an Array with each element being the logical line (removing comments and joining lines that end with backslash with the next line).

@param fh [IO] the file handle to read from.

@return [Array] each element being the logical lines with comments and

backslashes removed. Lines ending with a backslash gets joined with the
next line.

# File lib/bliftax.rb, line 146
def read_continuous_lines(fh)
  # Read in the entire BLIF file into an array so that
  # we can "peek" into the future.
  lines = []
  fh.each_line do |line|
    line.chomp!

    # Skip comment lines
    next if line.start_with?('#')
    next if line.strip.empty?

    continuous_lines = []
    loop do
      line = strip_comments(line)
      continuous_lines << strip_trailing_backslash(line)

      # If line ends with a backslash, there's more to come
      break unless line.end_with?('\\')

      line = fh.gets.chomp
    end

    lines << continuous_lines.join(SPACE).strip
  end

  lines
end

strip_comments(str) click to toggle source

Removes the trailing comments from a string.

@param str [String] the original string.

@return [String] string with the trailing whitespace and comments removed.

# File lib/bliftax.rb, line 179
def strip_comments(str)
  str.sub(/\s*\#.*$/, EMPTY).strip
end

strip_trailing_backslash(str) click to toggle source

Removes the trailing backslash from a string.

@param str [String] the original string.

@return [String] string with the trailing backslash removed.

# File lib/bliftax.rb, line 188
def strip_trailing_backslash(str)
  str.sub(/\\/, EMPTY)
end