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from cpython cimport PyBytes_FromStringAndSize
def make_varint(unsigned long long number):
"""
Writes integer of variable length using LEB128.
"""
cdef unsigned char to_write, i = 0
# unsigned PY_LONG_LONG checks integer on function call and
# raises OverflowError if integer overflows unsigned PY_LONG_LONG.
# Long enough for handling unsigned PY_LONG_LONG.
cdef unsigned char num_buf[32]
while True:
to_write = number & 0x7f
number >>= 7
if number:
num_buf[i] = to_write | 0x80
i += 1
else:
num_buf[i] = to_write
i += 1
break
return PyBytes_FromStringAndSize(<char *>num_buf, i)
def write_varint(unsigned long long number, buf):
"""
Writes integer of variable length using LEB128.
"""
cdef unsigned char to_write, i = 0
# unsigned PY_LONG_LONG checks integer on function call and
# raises OverflowError if integer overflows unsigned PY_LONG_LONG.
# Long enough for handling unsigned PY_LONG_LONG.
cdef unsigned char num_buf[32]
while True:
to_write = number & 0x7f
number >>= 7
if number:
num_buf[i] = to_write | 0x80
i += 1
else:
num_buf[i] = to_write
i += 1
break
buf.write(PyBytes_FromStringAndSize(<char *>num_buf, i))
def read_varint(f):
"""
Reads integer of variable length using LEB128.
"""
cdef unsigned char shift = 0
cdef unsigned long long i, result = 0
read_one = f.read_one
while True:
i = read_one()
result |= (i & 0x7f) << shift
shift += 7
if i < 0x80:
break
return result
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