def ASCII(ld: LogicalData) -> bytes:
"""
Representation code 20, Variable length identifier. Length up to 2**30-1 bytes.
[RP66V1 Appendix B Section B.20]
"""
size: int = UVARI(ld)
return ld.chunk(size)
def SNORM(ld: LogicalData) -> int:
"""
Representation code 13, Signed 2-byte integer.
[RP66V1 Appendix B Section B.13]
"""
by = ld.chunk(2)
value = struct.unpack('>h', by)
return value[0]
def ULONG(ld: LogicalData) -> int:
"""
Representation code 16, Unsigned 4-byte integer.
[RP66V1 Appendix B Section B.17]
"""
by = ld.chunk(4)
value = struct.unpack('>I', by)
return value[0]
def VSINGL(ld: LogicalData) -> float:
"""Representation code 6, VAX single precision floating point."""
by = ld.chunk(4)
s = (by[1] & 0x80)
m = ((by[0] & 0x7f) << 16) | (by[3] << 8) | by[2]
e = ((by[1] & 0x7f) << 1) | ((by[0] & 0x80) >> 7)
if e == 0 and s == 0:
# m is arbitrary
return 0.0
m = float(m) / (1 << 23)
value = (0.5 + m) * 2**(e - 128)
if s:
return -value
return value
def _pascal_string(ld: LogicalData) -> bytes:
"""Reads a Pascal like string from the LogicalData."""
siz: int = ld.read()
return ld.chunk(siz)
def FDOUBL(ld: LogicalData) -> float:
"""Representation code 7, IEEE double precision floating point."""
by = ld.chunk(8)
value = struct.unpack('>d', by)
return value[0]
def FSINGL(ld: LogicalData) -> float:
"""Representation code 2, IEEE single precision floating point."""
by = ld.chunk(4)
value = struct.unpack('>f', by)
return value[0]
def __init__(self, ld: LogicalData):
self.size = UNORM(ld)
self.producer_code = UNORM(ld)
self.encryption_information = ld.chunk(self.size)
self.bytes = ld.chunk(ld.remain)