in courses/machine_learning/deepdive2/end_to_end_ml/solutions/serving/application/lib/pyasn1/codec/ber/decoder.py [0:0]
def valueDecoder(self, substrate, asn1Spec,
tagSet=None, length=None, state=None,
decodeFun=None, substrateFun=None,
**options):
if tagSet[0].tagFormat != tag.tagFormatSimple:
raise error.PyAsn1Error('Simple tag format expected')
head, tail = substrate[:length], substrate[length:]
if not head:
return self._createComponent(asn1Spec, tagSet, 0.0, **options), tail
fo = oct2int(head[0])
head = head[1:]
if fo & 0x80: # binary encoding
if not head:
raise error.PyAsn1Error("Incomplete floating-point value")
if LOG:
LOG('decoding binary encoded REAL')
n = (fo & 0x03) + 1
if n == 4:
n = oct2int(head[0])
head = head[1:]
eo, head = head[:n], head[n:]
if not eo or not head:
raise error.PyAsn1Error('Real exponent screwed')
e = oct2int(eo[0]) & 0x80 and -1 or 0
while eo: # exponent
e <<= 8
e |= oct2int(eo[0])
eo = eo[1:]
b = fo >> 4 & 0x03 # base bits
if b > 2:
raise error.PyAsn1Error('Illegal Real base')
if b == 1: # encbase = 8
e *= 3
elif b == 2: # encbase = 16
e *= 4
p = 0
while head: # value
p <<= 8
p |= oct2int(head[0])
head = head[1:]
if fo & 0x40: # sign bit
p = -p
sf = fo >> 2 & 0x03 # scale bits
p *= 2 ** sf
value = (p, 2, e)
elif fo & 0x40: # infinite value
if LOG:
LOG('decoding infinite REAL')
value = fo & 0x01 and '-inf' or 'inf'
elif fo & 0xc0 == 0: # character encoding
if not head:
raise error.PyAsn1Error("Incomplete floating-point value")
if LOG:
LOG('decoding character encoded REAL')
try:
if fo & 0x3 == 0x1: # NR1
value = (int(head), 10, 0)
elif fo & 0x3 == 0x2: # NR2
value = float(head)
elif fo & 0x3 == 0x3: # NR3
value = float(head)
else:
raise error.SubstrateUnderrunError(
'Unknown NR (tag %s)' % fo
)
except ValueError:
raise error.SubstrateUnderrunError(
'Bad character Real syntax'
)
else:
raise error.SubstrateUnderrunError(
'Unknown encoding (tag %s)' % fo
)
return self._createComponent(asn1Spec, tagSet, value, **options), tail