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from enum import Enum, unique, auto
@unique
class Coding(Enum):
FIXED_CODE = auto() # f(x) - fixed code to assert
UNSIGNED_FIXED = auto() # u(x) - unsigned int with a fixed number of bits
UNSIGNED_VARIABLE = auto() # u(v) - unsigned int with a variable number of bits
UNSIGNED_EXP = auto() # ue(v) - unsigned int wit exp golomb coding
SIGNED_EXP = auto() # se(v) - signed int with exp golomb coding
def isCodingType(descriptor : str):
try:
CodingType(descriptor)
except:
return False
return True
class CodingType():
def __init__(self, descriptor : str):
self.length = 0
self.codingType = None
self.parseCodingType(descriptor)
def parseCodingType(self, descriptor : str):
if (descriptor.startswith("f(")):
self.codingType = Coding.FIXED_CODE
self.length = int(descriptor[2:-1])
elif (descriptor.startswith("u(v)")):
self.codingType = Coding.UNSIGNED_VARIABLE
elif (descriptor.startswith("u(")):
self.codingType = Coding.UNSIGNED_FIXED
self.length = int(descriptor[2:-1])
elif (descriptor.startswith("ue(v)")):
self.codingType = Coding.UNSIGNED_EXP
elif (descriptor.startswith("se(v)")):
self.codingType = Coding.SIGNED_EXP
else:
raise SyntaxError("Unknown descriptor type " + descriptor)
def __str__(self):
if (self.codingType == Coding.FIXED_CODE):
return f"f({self.length})"
if (self.codingType == Coding.UNSIGNED_VARIABLE):
return "u(v)"
if (self.codingType == Coding.UNSIGNED_FIXED):
return f"u({self.length})"
if (self.codingType == Coding.UNSIGNED_EXP):
return "ue(v)"
if (self.codingType == Coding.SIGNED_EXP):
return "se(v)"
return "Err"
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