Source code for cocotb.utils

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"""Collection of handy functions."""

import ctypes
import math
import os
import sys
import weakref
import functools
import warnings

from cocotb import simulator


def _get_simulator_precision():
    # cache and replace this function
    precision = simulator.get_precision()
    global _get_simulator_precision
    _get_simulator_precision = precision.__int__
    return _get_simulator_precision()


def get_python_integer_types():
    warnings.warn(
        "This is an internal cocotb function, use six.integer_types instead",
        DeprecationWarning)
    return (int,)


# Simulator helper functions
[docs]def get_sim_time(units=None): """Retrieves the simulation time from the simulator. Args: units (str or None, optional): String specifying the units of the result (one of ``None``, ``'fs'``, ``'ps'``, ``'ns'``, ``'us'``, ``'ms'``, ``'sec'``). ``None`` will return the raw simulation time. Returns: The simulation time in the specified units. """ timeh, timel = simulator.get_sim_time() result = (timeh << 32 | timel) if units is not None: result = get_time_from_sim_steps(result, units) return result
def _ldexp10(frac, exp): """ Like math.ldexp, but base 10 """ # using * or / separately prevents rounding errors if `frac` is a # high-precision type if exp > 0: return frac * (10 ** exp) else: return frac / (10 ** -exp)
[docs]def get_time_from_sim_steps(steps, units): """Calculates simulation time in the specified *units* from the *steps* based on the simulator precision. Args: steps (int): Number of simulation steps. units (str): String specifying the units of the result (one of ``'fs'``, ``'ps'``, ``'ns'``, ``'us'``, ``'ms'``, ``'sec'``). Returns: The simulation time in the specified units. """ return _ldexp10(steps, _get_simulator_precision() - _get_log_time_scale(units))
[docs]def get_sim_steps(time, units=None): """Calculates the number of simulation time steps for a given amount of *time*. Args: time (numbers.Real or decimal.Decimal): The value to convert to simulation time steps. units (str or None, optional): String specifying the units of the result (one of ``None``, ``'fs'``, ``'ps'``, ``'ns'``, ``'us'``, ``'ms'``, ``'sec'``). ``None`` means time is already in simulation time steps. Returns: int: The number of simulation time steps. Raises: :exc:`ValueError`: If given *time* cannot be represented by simulator precision. """ result = time if units is not None: result = _ldexp10(result, _get_log_time_scale(units) - _get_simulator_precision()) result_rounded = math.floor(result) if result_rounded != result: raise ValueError("Unable to accurately represent {0}({1}) with the " "simulator precision of 1e{2}".format( time, units, _get_simulator_precision())) return int(result_rounded)
def _get_log_time_scale(units): """Retrieves the ``log10()`` of the scale factor for a given time unit. Args: units (str): String specifying the units (one of ``'fs'``, ``'ps'``, ``'ns'``, ``'us'``, ``'ms'``, ``'sec'``). Returns: The the ``log10()`` of the scale factor for the time unit. """ scale = { 'fs' : -15, 'ps' : -12, 'ns' : -9, 'us' : -6, 'ms' : -3, 'sec': 0} units_lwr = units.lower() if units_lwr not in scale: raise ValueError("Invalid unit ({0}) provided".format(units)) else: return scale[units_lwr] # Ctypes helper functions
[docs]def pack(ctypes_obj): """Convert a :mod:`ctypes` structure into a Python string. Args: ctypes_obj (ctypes.Structure): The :mod:`ctypes` structure to convert to a string. Returns: New Python string containing the bytes from memory holding *ctypes_obj*. """ return ctypes.string_at(ctypes.addressof(ctypes_obj), ctypes.sizeof(ctypes_obj))
[docs]def unpack(ctypes_obj, string, bytes=None): """Unpack a Python string into a :mod:`ctypes` structure. If the length of *string* is not the correct size for the memory footprint of the :mod:`ctypes` structure then the *bytes* keyword argument must be used. Args: ctypes_obj (ctypes.Structure): The :mod:`ctypes` structure to pack into. string (str): String to copy over the *ctypes_obj* memory space. bytes (int, optional): Number of bytes to copy. Defaults to ``None``, meaning the length of *string* is used. Raises: :exc:`ValueError`: If length of *string* and size of *ctypes_obj* are not equal. :exc:`MemoryError`: If *bytes* is longer than size of *ctypes_obj*. """ if bytes is None: if len(string) != ctypes.sizeof(ctypes_obj): raise ValueError("Attempt to unpack a string of size %d into a \ struct of size %d" % (len(string), ctypes.sizeof(ctypes_obj))) bytes = len(string) if bytes > ctypes.sizeof(ctypes_obj): raise MemoryError("Attempt to unpack %d bytes over an object \ of size %d" % (bytes, ctypes.sizeof(ctypes_obj))) ctypes.memmove(ctypes.addressof(ctypes_obj), string, bytes)
import cocotb.ANSI as ANSI # A note on the use of latin1 in the deprecations below: # Latin1 is the only encoding `e` that satisfies # `all(chr(x).encode(e) == bytes([x]) for x in range(255))` # Our use of `ord` and `chr` throughout other bits of code make this the most # compatible choice of encoding. Under this convention, old code can be upgraded # by changing "binary" strings from `"\x12\x34"` to `b"\x12\x34"`. def _sane(x: bytes) -> str: r = "" for j in x: if (j < 32) or (j >= 127): r += "." else: r += chr(j) return r
[docs]def hexdump(x: bytes) -> str: """Hexdump a buffer. Args: x: Object that supports conversion to :class:`bytes`. Returns: A string containing the hexdump. .. deprecated:: 1.4 Passing a :class:`str` to this function is deprecated, as it is not an appropriate type for binary data. Doing so anyway will encode the string to latin1. Example: >>> print(hexdump(b'this somewhat long string')) 0000 74 68 69 73 20 73 6F 6D 65 77 68 61 74 20 6C 6F this somewhat lo 0010 6E 67 20 73 74 72 69 6E 67 ng string <BLANKLINE> """ # adapted from scapy.utils.hexdump rs = "" if isinstance(x, str): warnings.warn( "Passing a string to hexdump is deprecated, pass bytes instead", DeprecationWarning, stacklevel=2) x = x.encode('latin1') x = b"%b" % x l = len(x) i = 0 while i < l: rs += "%04x " % i for j in range(16): if i + j < l: rs += "%02X " % x[i + j] else: rs += " " if j % 16 == 7: rs += "" rs += " " rs += _sane(x[i:i + 16]) + "\n" i += 16 return rs
[docs]def hexdiffs(x: bytes, y: bytes) -> str: r"""Return a diff string showing differences between two binary strings. Args: x: Object that supports conversion to :class:`bytes`. y: Object that supports conversion to :class:`bytes`. .. deprecated:: 1.4 Passing :class:`str`\ s to this function is deprecated, as it is not an appropriate type for binary data. Doing so anyway will encode the string to latin1. Example: >>> print(hexdiffs(b'a', b'b')) 0000 61 a 0000 62 b <BLANKLINE> >>> print(hexdiffs(b'this short thing', b'this also short')) 0000 746869732073686F 7274207468696E67 this short thing 0000 7468697320616C73 6F 2073686F7274 this also short <BLANKLINE> """ # adapted from scapy.utils.hexdiff def highlight(string: str, colour=ANSI.COLOR_HILITE_HEXDIFF_DEFAULT) -> str: """Highlight with ANSI colors if possible/requested and not running in GUI.""" if want_color_output(): return colour + string + ANSI.COLOR_DEFAULT else: return string x_is_str = isinstance(x, str) y_is_str = isinstance(y, str) if x_is_str or y_is_str: warnings.warn( "Passing strings to hexdiffs is deprecated, pass bytes instead", DeprecationWarning, stacklevel=2) if x_is_str: x = x.encode('latin1') if y_is_str: y = y.encode('latin1') rs = "" x = (b'%b' % x)[::-1] y = (b'%b' % y)[::-1] SUBST = 1 INSERT = 1 d = {} d[-1, -1] = 0, (-1, -1) for j in range(len(y)): d[-1, j] = d[-1, j - 1][0] + INSERT, (-1, j - 1) for i in range(len(x)): d[i, -1] = d[i - 1, -1][0] + INSERT, (i - 1, -1) for j in range(len(y)): for i in range(len(x)): d[i, j] = min((d[i-1, j-1][0] + SUBST*(x[i] != y[j]), (i-1, j-1)), (d[i - 1, j][0] + INSERT, (i - 1, j)), (d[i, j - 1][0] + INSERT, (i, j - 1))) backtrackx = [] backtracky = [] i = len(x) - 1 j = len(y) - 1 while not (i == j == -1): i2, j2 = d[i, j][1] backtrackx.append(x[i2+1:i+1]) backtracky.append(y[j2+1:j+1]) i, j = i2, j2 x = y = i = 0 colorize = { 0: lambda x: x, # noqa -1: lambda x: x, # noqa 1: lambda x: x} # noqa dox = 1 doy = 0 l = len(backtrackx) while i < l: separate = 0 linex = backtrackx[i:i+16] liney = backtracky[i:i+16] xx = sum(len(k) for k in linex) yy = sum(len(k) for k in liney) if dox and not xx: dox = 0 doy = 1 if dox and linex == liney: doy = 1 if dox: xd = y j = 0 while not linex[j]: j += 1 xd -= 1 if dox != doy: rs += highlight("%04x" % xd) + " " else: rs += highlight("%04x" % xd, colour=ANSI.COLOR_HILITE_HEXDIFF_1) + " " x += xx line = linex else: rs += " " if doy: yd = y j = 0 while not liney[j]: j += 1 yd -= 1 if doy - dox != 0: rs += " " + highlight("%04x" % yd) else: rs += highlight("%04x" % yd, colour=ANSI.COLOR_HILITE_HEXDIFF_1) y += yy line = liney else: rs += " " rs += " " cl = "" for j in range(16): if i + j < l: if line[j]: char_j, = line[j] if linex[j] != liney[j]: rs += highlight("%02X" % char_j, colour=ANSI.COLOR_HILITE_HEXDIFF_2) else: rs += "%02X" % char_j if linex[j] == liney[j]: cl += highlight(_sane(line[j]), colour=ANSI.COLOR_HILITE_HEXDIFF_3) else: cl += highlight(_sane(line[j]), colour=ANSI.COLOR_HILITE_HEXDIFF_4) else: rs += " " cl += " " else: rs += " " if j == 7: rs += " " rs += " " + cl + '\n' if doy or not yy: doy = 0 dox = 1 i += 16 else: if yy: dox = 0 doy = 1 else: i += 16 return rs
[docs]class ParametrizedSingleton(type): """A metaclass that allows class construction to reuse an existing instance. We use this so that :class:`RisingEdge(sig) <cocotb.triggers.RisingEdge>` and :class:`Join(coroutine) <cocotb.triggers.Join>` always return the same instance, rather than creating new copies. """ def __init__(cls, *args, **kwargs): # Attach a lookup table to this class. # Weak such that if the instance is no longer referenced, it can be # collected. cls.__instances = weakref.WeakValueDictionary() def __singleton_key__(cls, *args, **kwargs): """Convert the construction arguments into a normalized representation that uniquely identifies this singleton. """ # Could default to something like this, but it would be slow # return tuple(inspect.Signature(cls).bind(*args, **kwargs).arguments.items()) raise NotImplementedError def __call__(cls, *args, **kwargs): key = cls.__singleton_key__(*args, **kwargs) try: return cls.__instances[key] except KeyError: # construct the object as normal self = super(ParametrizedSingleton, cls).__call__(*args, **kwargs) cls.__instances[key] = self return self
[docs]def reject_remaining_kwargs(name, kwargs): """ Helper function to emulate Python 3 keyword-only arguments. Use as:: def func(x1, **kwargs): a = kwargs.pop('a', 1) b = kwargs.pop('b', 2) reject_remaining_kwargs('func', kwargs) ... To emulate the Python 3 syntax:: def func(x1, *, a=1, b=2): ... .. deprecated:: 1.4 Since the minimum supported Python version is now 3.5, this function is not needed. """ warnings.warn( "reject_remaining_kwargs is deprecated and will be removed, use " "Python 3 keyword-only arguments directly.", DeprecationWarning, stacklevel=2) if kwargs: # match the error message to what Python 3 produces bad_arg = next(iter(kwargs)) raise TypeError( '{}() got an unexpected keyword argument {!r}'.format(name, bad_arg) )
[docs]class lazy_property: """ A property that is executed the first time, then cached forever. It does this by replacing itself on the instance, which works because unlike `@property` it does not define __set__. This should be used for expensive members of objects that are not always used. """ def __init__(self, fget): self.fget = fget # copy the getter function's docstring and other attributes functools.update_wrapper(self, fget) def __get__(self, obj, cls): if obj is None: return self value = self.fget(obj) setattr(obj, self.fget.__qualname__, value) return value
[docs]def want_color_output(): """Return ``True`` if colored output is possible/requested and not running in GUI. Colored output can be explicitly requested by setting :envvar:`COCOTB_ANSI_OUTPUT` to ``1``. """ want_color = sys.stdout.isatty() # default to color for TTYs if os.getenv("NO_COLOR") is not None: want_color = False if os.getenv("COCOTB_ANSI_OUTPUT", default='0') == '1': want_color = True if os.getenv("GUI", default='0') == '1': want_color = False return want_color
if __name__ == "__main__": import random a = "" for char in range(random.randint(250, 500)): a += chr(random.randint(0, 255)) b = a for error in range(random.randint(2, 9)): offset = random.randint(0, len(a)) b = b[:offset] + chr(random.randint(0, 255)) + b[offset+1:] diff = hexdiffs(a, b) print(diff) space = '\n' + (" " * 20) print(space.join(diff.split('\n')))
[docs]def remove_traceback_frames(tb_or_exc, frame_names): """ Strip leading frames from a traceback Args: tb_or_exc (Union[traceback, BaseException, exc_info]): Object to strip frames from. If an exception is passed, creates a copy of the exception with a new shorter traceback. If a tuple from `sys.exc_info` is passed, returns the same tuple with the traceback shortened frame_names (List[str]): Names of the frames to strip, which must be present. """ # self-invoking overloads if isinstance(tb_or_exc, BaseException): exc = tb_or_exc return exc.with_traceback( remove_traceback_frames(exc.__traceback__, frame_names) ) elif isinstance(tb_or_exc, tuple): exc_type, exc_value, exc_tb = tb_or_exc exc_tb = remove_traceback_frames(exc_tb, frame_names) return exc_type, exc_value, exc_tb # base case else: tb = tb_or_exc for frame_name in frame_names: assert tb.tb_frame.f_code.co_name == frame_name tb = tb.tb_next return tb