Subversion Repositories ssbcc

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#

# Copyright 2012, Sinclair R.F., Inc.

#

# Utilities required by ssbcc

#

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import math

import re

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#

# Classes

#

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class SSBCCException(Exception):

  """

  Exception class for ssbcc.

  """

  def __init__(self,message):

    self.message = message;

  def __str__(self):

    return self.message;

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#

# Methods

#

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def CeilLog2(v):

  """

  Return the smallest integer that has a power of 2 greater than or equal to

  the argument.

  """

  tmp = int(math.log(v,2));

  while 2**tmp < v:

    tmp = tmp + 1;

  return tmp;

def CeilPow2(v):

  """

  Return the smallest power of 2 greater than or equal to the argument.

  """

  return 2**CeilLog2(v);

def ExtractBits(v,bits):

  """

  Extract the bits specified by bits from v.

  bits must have a Verilog-type format.  I.e., [7:0], [0+:8], etc.

  """

  if type(v) != int:

    raise SSBCCException('%s must be an int' % v);

  if re.match(r'[[]\d+:\d+]$',bits):

    cmd = re.findall(r'[[](\d+):(\d+)]$',bits)[0];

    b0 = int(cmd[1]);

    bL = int(cmd[0]) - b0 + 1;

  elif re.match(r'[[]\d+\+:\d+]$',bits):

    cmd = re.findall(r'[[](\d+)\+:(\d+)]$',bits)[0];

    b0 = int(cmd[0]);

    bL = int(cmd[1]);

  else:

    raise SSBCCException('Unrecognized bit slice format:  %s' % bits);

  if not 1 <= bL <= 8:

    raise SSBCCException('Malformed range "%s" doesn\'t provide 1 to 8 bits' % bits)

  v /= 2**b0;

  v %= 2**bL;

  return v;

def IntValue(v):

  """

  Convert a Verilog format integer into an integer value.

  """

  ov = 0;

  for vv in [v[i] for i in range(len(v)) if '0' <= v[i] <= '9']:

    ov *= 10;

    ov += ord(vv)-ord('0');

  return ov;

def IsPowerOf2(v):

  """

  Indicate whether or not the argument is a power of 2.

  """

  return v == 2**int(math.log(v,2)+0.5);

def LoadFile(filename):

  """

  Load the file into a list with the line contents and line numbers.\n

  filename is either the name of the file or a file object.\n

  Note:  The file object is closed in either case.

  """

  if type(filename) == str:

    try:

      filename = file(filename);

    except:

      raise SSBCCException('Error opening "%s"' % filename);

  elif type(filename) == file:

    pass;

  else:

    raise Exception('Unexpected argument type:  %s' % type(filename))

  v = list();

  ixLine = 0;

  for tmpLine in filename:

    ixLine += 1;

    while tmpLine and tmpLine[-1] in ('\n','\r',):

      tmpLine = tmpLine[0:-1];

    v.append((tmpLine,ixLine,));

  filename.close();

  return v;

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#

# Unit test.

#

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if __name__ == "__main__":

  def Test_ExtractBits(v,bits,vExpect):

    vGot = ExtractBits(v,bits);

    if vGot != vExpect:

      raise Exception('ExtractBits failed: 0x%04X %s ==> 0x%02X instead of 0x%02X' % (v,bits,ExtractBits(v,bits),vExpect,));

  for v in (256,257,510,):

    Test_ExtractBits(v,'[0+:8]',v%256);

    Test_ExtractBits(v,'[7:0]',v%256);

    Test_ExtractBits(v,'[4+:6]',(v/16)%64);

    Test_ExtractBits(v,'[9:4]',(v/16)%64);

  print 'Unit test passed';