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[TupleVariations] Optimize serialization loops

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This commit is contained in:
Behdad Esfahbod 2021-04-07 17:06:24 -06:00
parent b1b672e17e
commit 62a89bc3d5
1 changed files with 33 additions and 17 deletions
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50
Lib/fontTools/ttLib/tables/TupleVariation.py
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@ -346,21 +346,24 @@ class TupleVariation(object):
return bytearr return bytearr
@staticmethod @staticmethod
def encodeDeltaRunAsZeroes_(deltas, pos, bytearr): def encodeDeltaRunAsZeroes_(deltas, offset, bytearr):
runLength = 0 pos = offset
numDeltas = len(deltas) numDeltas = len(deltas)
while pos < numDeltas and runLength < 64 and deltas[pos] == 0: while pos < numDeltas and deltas[pos] == 0:
pos += 1 pos += 1
runLength += 1 runLength = pos - offset
bytearr.append(DELTAS_ARE_ZERO | (runLength - 1)) while runLength >= 64:
bytearr.append(DELTAS_ARE_ZERO | 63)
runLength -= 64
if runLength:
bytearr.append(DELTAS_ARE_ZERO | (runLength - 1))
return pos return pos
@staticmethod @staticmethod
def encodeDeltaRunAsBytes_(deltas, offset, bytearr): def encodeDeltaRunAsBytes_(deltas, offset, bytearr):
runLength = 0
pos = offset pos = offset
numDeltas = len(deltas) numDeltas = len(deltas)
while pos < numDeltas and runLength < 64: while pos < numDeltas:
value = deltas[pos] value = deltas[pos]
if value < -128 or value > 127: if value < -128 or value > 127:
break break
@ -375,17 +378,22 @@ class TupleVariation(object):
if value == 0 and pos+1 < numDeltas and deltas[pos+1] == 0: if value == 0 and pos+1 < numDeltas and deltas[pos+1] == 0:
break break
pos += 1 pos += 1
runLength += 1 runLength = pos - offset
bytearr.append(runLength - 1) while runLength >= 64:
bytearr.extend(array.array('b', deltas[offset:pos])) bytearr.append(63)
bytearr.extend(array.array('b', deltas[offset:offset+64]))
offset += 64
runLength -= 64
if runLength:
bytearr.append(runLength - 1)
bytearr.extend(array.array('b', deltas[offset:pos]))
return pos return pos
@staticmethod @staticmethod
def encodeDeltaRunAsWords_(deltas, offset, bytearr): def encodeDeltaRunAsWords_(deltas, offset, bytearr):
runLength = 0
pos = offset pos = offset
numDeltas = len(deltas) numDeltas = len(deltas)
while pos < numDeltas and runLength < 64: while pos < numDeltas:
value = deltas[pos] value = deltas[pos]
# Within a word-encoded run of deltas, it is easiest # Within a word-encoded run of deltas, it is easiest
# to start a new run (with a different encoding) # to start a new run (with a different encoding)
@ -407,11 +415,19 @@ class TupleVariation(object):
if isByteEncodable(value) and pos+1 < numDeltas and isByteEncodable(deltas[pos+1]): if isByteEncodable(value) and pos+1 < numDeltas and isByteEncodable(deltas[pos+1]):
break break
pos += 1 pos += 1
runLength += 1 runLength = pos - offset
bytearr.append(DELTAS_ARE_WORDS | (runLength - 1)) while runLength >= 64:
a = array.array('h', deltas[offset:pos]) bytearr.append(DELTAS_ARE_WORDS | 63)
if sys.byteorder != "big": a.byteswap() a = array.array('h', deltas[offset:offset+64])
bytearr.extend(a) if sys.byteorder != "big": a.byteswap()
bytearr.extend(a)
offset += 64
runLength -= 64
if runLength:
bytearr.append(DELTAS_ARE_WORDS | (runLength - 1))
a = array.array('h', deltas[offset:pos])
if sys.byteorder != "big": a.byteswap()
bytearr.extend(a)
return pos return pos
@staticmethod @staticmethod