tools/edid/edid.py

# Lint as: python2, python3
# Copyright 2014 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.


"""Provides EDID class with methods for parsing info."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import array

import basic_display
import chromaticity
import descriptor
import error_check
import established_timings
import extensions
from six.moves import range
import standard_timings


class Edid(object):
  """Defines methods and properties for accesing an EDID object's content."""

  def __init__(self, e):
    """Creates an Edid object with a list of bytes.

    Args:
      e: The list of bytes that make up this EDID.
    """
    self._edid = e

  def GetData(self, start=None, end=None):
    """Fetches the raw data for the entire or part of the EDID.

    Args:
      start: The index of the first element to include.
      end: The index of the first element to exclude.

    Returns:
      A list of bytes.
    """
    return self._edid[start:end]

  @property
  def manufacturer_id(self):
    """Fetches the manufacturer ID.

    Returns:
      A three letter string that represents the manufacturer ID.
    """
    manu_id = ((self._edid[0x08] << 8) + self._edid[0x09])

    c1 = self._ConvertToLetter((manu_id >> 10) & 0x1F)
    c2 = self._ConvertToLetter((manu_id >> 5) & 0x1F)
    c3 = self._ConvertToLetter(manu_id & 0x1F)

    return c1 + c2 + c3

  @property
  def product_code(self):
    """Fetches the ID Product code.

    This code is used to differentiate between different models from the same
    manufacturer (i.e., a model number). Bytes 10-11, little endian.

    Returns:
      An integer denoting the product code.
    """

    return (self._edid[0x0B] << 8) + self._edid[0x0A]

  @property
  def serial_number(self):
    """Fetches the serial number.

    Used to differentiate between instances of the same display model.

    Returns:
      An integer denoting serial number or None.
    """
    sn = ((self._edid[0x0F] << 24) + (self._edid[0x0E] << 16) +
          (self._edid[0x0D] << 8) + (self._edid[0x0C]))

    return sn if sn else None

  @property
  def manufacturing_week(self):
    """Fetches the week of manufacturing.

    Returns:
      None, if unspecified, or an integer indicating the week number.
    """
    if self._edid[0x10] in [0, 255]:
      return None
    else:
      return self._edid[0x10]

  @property
  def manufacturing_year(self):
    """Fetches the year of manufacturing.

    Returns:
      None, if unspecified, or an integer indicating the year.
    """
    if self._edid[0x10] == 255:
      return None
    else:
      return self._edid[0x11] + 1990

  @property
  def model_year(self):
    """Fetches the model year.

    Model year is only specified if week is set to 255.

    Returns:
      None, if unspecified, or an integer indicating the model year.
    """
    if self._edid[0x10] == 255:
      return self._edid[0x11] + 1990
    else:
      return None

  @property
  def extension_count(self):
    """Fetches the number of extensions in this EDID.

    Returns:
      An integer denoting the number of extensions.
    """
    return self._edid[0x7E]

  def _ConvertToLetter(self, b):
    """Converts a 5-digit binary number into a letter.

    Called when printing manufacturing info.

    Args:
      b: The binary number being converted into a character.

    Returns:
      A single character (upper-case letter).
    """
    return chr(b+64)

  @property
  def edid_version(self):
    """Fetches the EDID version (1.3 or 1.4).

    Returns:
      A string indicating the EDID version.
    """
    return '%d.%d' % (self._edid[0x12], self._edid[0x13])

  @property
  def basic_display(self):
    """Fetches the Basic Display information in this EDID.

    Returns:
      A basic_display.BasicDisplay object.
    """
    return basic_display.BasicDisplay(self._edid, self.edid_version)

  @property
  def chromaticity(self):
    """Fetches the Chromaticity information in this EDID.

    Returns:
      A chromaticity.Chromaticity object.
    """
    return chromaticity.Chromaticity(self._edid)

  @property
  def established_timings(self):
    """Fetches the Established Timings information in this EDID.

    Returns:
      An established_timings.EstablishedTimings object.
    """
    return established_timings.EstablishedTimings(self._edid)

  @property
  def standard_timings(self):
    """Fetches the Standard Timing information in this EDID.

    Returns:
      A standard_timings.StandardTiming object.
    """
    base = 38
    sts = []
    for x in range(0, 8):
      st = standard_timings.GetStandardTiming(self._edid, (base + (x * 2)),
                                              self.edid_version)
      if st:
        sts.append(st)
    return sts

  def GetDescriptor(self, index):
    """Fetches a single Descriptor's information in this EDID.

    Args:
      index: The descriptor index (0-3) within the EDID.

    Returns:
      A single descriptor.Descriptor object.

    Raises:
      IndexError: If index is not in the range 0-3.
    """
    base = 54  # Descriptor blocks begin at byte 54 in base EDID
    return descriptor.GetDescriptor(self._edid, (base + (index * 18)),
                                    self.edid_version)

  @property
  def descriptors(self):
    """Fetches all descriptors in a base EDID.

    Returns:
      A list of descriptor.Descriptor objects.
    """
    descs = []
    for x in range(0, 4):
      desc = self.GetDescriptor(x)
      if desc:
        descs.append(desc)
    return descs

  def GetExtension(self, index):
    """Fetches an Extension's information in this EDID.

    Args:
      index: The index of the extension (starting at 1).

    Returns:
      A single extensions.Extension object.
    """
    return extensions.GetExtension(self._edid, index, self.edid_version)

  def GetErrors(self):
    """Checks an EDID for errors by calling error_check module.

    Returns:
      A list of error.Error objects.
    """
    return error_check.GetErrors(self.GetData(), self.edid_version)

  def ConvertToBinary(self, filename):
    """Converts an EDID object into a binary blob.

    Args:
      filename: The string filename of the text file.
    """
    with open(filename, 'wb') as myfile:
      blob = array.array('B', self._edid).tostring()
      myfile.write(blob)