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"""
The format table for standard sizes and alignments.
"""
# Note: we follow Python 2.5 in being strict about the ranges of accepted
# values when packing.
import struct
from rpython.rlib.objectmodel import specialize
from rpython.rlib.rarithmetic import r_uint, r_longlong, r_ulonglong
from rpython.rlib.rstruct import ieee
from rpython.rlib.rstruct.error import StructError, StructOverflowError
from rpython.rlib.unroll import unrolling_iterable
def pack_pad(fmtiter, count):
fmtiter.result.append_multiple_char('\x00', count)
def pack_char(fmtiter):
string = fmtiter.accept_str_arg()
if len(string) != 1:
raise StructError("expected a string of length 1")
c = string[0] # string->char conversion for the annotator
fmtiter.result.append(c)
def pack_bool(fmtiter):
c = '\x01' if fmtiter.accept_bool_arg() else '\x00'
fmtiter.result.append(c)
def pack_string(fmtiter, count):
string = fmtiter.accept_str_arg()
if len(string) < count:
fmtiter.result.append(string)
fmtiter.result.append_multiple_char('\x00', count - len(string))
else:
fmtiter.result.append_slice(string, 0, count)
def pack_pascal(fmtiter, count):
string = fmtiter.accept_str_arg()
prefix = len(string)
if prefix >= count:
prefix = count - 1
if prefix < 0:
raise StructError("bad '0p' in struct format")
if prefix > 255:
prefixchar = '\xff'
else:
prefixchar = chr(prefix)
fmtiter.result.append(prefixchar)
fmtiter.result.append_slice(string, 0, prefix)
fmtiter.result.append_multiple_char('\x00', count - (1 + prefix))
def make_float_packer(size):
def packer(fmtiter):
fl = fmtiter.accept_float_arg()
try:
return ieee.pack_float(fmtiter.result, fl, size, fmtiter.bigendian)
except OverflowError:
assert size == 4
raise StructOverflowError("float too large for format 'f'")
return packer
# ____________________________________________________________
native_int_size = struct.calcsize("l")
def min_max_acc_method(size, signed):
if signed:
min = -(2 ** (8*size-1))
max = (2 ** (8*size-1)) - 1
if size <= native_int_size:
accept_method = 'accept_int_arg'
min = int(min)
max = int(max)
else:
accept_method = 'accept_longlong_arg'
min = r_longlong(min)
max = r_longlong(max)
else:
min = 0
max = (2 ** (8*size)) - 1
if size < native_int_size:
accept_method = 'accept_int_arg'
elif size == native_int_size:
accept_method = 'accept_uint_arg'
min = r_uint(min)
max = r_uint(max)
else:
accept_method = 'accept_ulonglong_arg'
min = r_ulonglong(min)
max = r_ulonglong(max)
return min, max, accept_method
def make_int_packer(size, signed, _memo={}):
key = size, signed
try:
return _memo[key]
except KeyError:
pass
min, max, accept_method = min_max_acc_method(size, signed)
if size > 1:
plural = "s"
else:
plural = ""
errormsg = "argument out of range for %d-byte%s integer format" % (size,
plural)
unroll_revrange_size = unrolling_iterable(range(size-1, -1, -1))
def pack_int(fmtiter):
method = getattr(fmtiter, accept_method)
value = method()
if not min <= value <= max:
raise StructError(errormsg)
if fmtiter.bigendian:
for i in unroll_revrange_size:
x = (value >> (8*i)) & 0xff
fmtiter.result.append(chr(x))
else:
for i in unroll_revrange_size:
fmtiter.result.append(chr(value & 0xff))
value >>= 8
_memo[key] = pack_int
return pack_int
# ____________________________________________________________
@specialize.argtype(0)
def unpack_pad(fmtiter, count):
fmtiter.read(count)
@specialize.argtype(0)
def unpack_char(fmtiter):
fmtiter.appendobj(fmtiter.read(1))
@specialize.argtype(0)
def unpack_bool(fmtiter):
c = ord(fmtiter.read(1)[0])
fmtiter.appendobj(bool(c))
@specialize.argtype(0)
def unpack_string(fmtiter, count):
fmtiter.appendobj(fmtiter.read(count))
@specialize.argtype(0)
def unpack_pascal(fmtiter, count):
if count == 0:
raise StructError("bad '0p' in struct format")
data = fmtiter.read(count)
end = 1 + ord(data[0])
if end > count:
end = count
fmtiter.appendobj(data[1:end])
def make_float_unpacker(size):
@specialize.argtype(0)
def unpacker(fmtiter):
data = fmtiter.read(size)
fmtiter.appendobj(ieee.unpack_float(data, fmtiter.bigendian))
return unpacker
# ____________________________________________________________
def make_int_unpacker(size, signed, _memo={}):
try:
return _memo[size, signed]
except KeyError:
pass
if signed:
if size <= native_int_size:
inttype = int
else:
inttype = r_longlong
else:
if size < native_int_size:
inttype = int
elif size == native_int_size:
inttype = r_uint
else:
inttype = r_ulonglong
unroll_range_size = unrolling_iterable(range(size))
@specialize.argtype(0)
def unpack_int(fmtiter):
intvalue = inttype(0)
s = fmtiter.read(size)
idx = 0
if fmtiter.bigendian:
for i in unroll_range_size:
x = ord(s[idx])
if signed and i == 0 and x >= 128:
x -= 256
intvalue <<= 8
intvalue |= inttype(x)
idx += 1
else:
for i in unroll_range_size:
x = ord(s[idx])
if signed and i == size - 1 and x >= 128:
x -= 256
intvalue |= inttype(x) << (8*i)
idx += 1
fmtiter.appendobj(intvalue)
_memo[size, signed] = unpack_int
return unpack_int
# ____________________________________________________________
standard_fmttable = {
'x':{ 'size' : 1, 'pack' : pack_pad, 'unpack' : unpack_pad,
'needcount' : True },
'c':{ 'size' : 1, 'pack' : pack_char, 'unpack' : unpack_char},
's':{ 'size' : 1, 'pack' : pack_string, 'unpack' : unpack_string,
'needcount' : True },
'p':{ 'size' : 1, 'pack' : pack_pascal, 'unpack' : unpack_pascal,
'needcount' : True },
'f':{ 'size' : 4, 'pack' : make_float_packer(4),
'unpack' : make_float_unpacker(4)},
'd':{ 'size' : 8, 'pack' : make_float_packer(8),
'unpack' : make_float_unpacker(8)},
'?':{ 'size' : 1, 'pack' : pack_bool, 'unpack' : unpack_bool},
}
for c, size in [('b', 1), ('h', 2), ('i', 4), ('l', 4), ('q', 8)]:
standard_fmttable[c] = {'size': size,
'pack': make_int_packer(size, True),
'unpack': make_int_unpacker(size, True)}
standard_fmttable[c.upper()] = {'size': size,
'pack': make_int_packer(size, False),
'unpack': make_int_unpacker(size, False)}
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