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"""
Buffer protocol support.
"""
from rpython.rtyper.lltypesystem import lltype, llmemory, rffi
from rpython.rtyper.lltypesystem.lloperation import llop
from rpython.rtyper.lltypesystem.rstr import STR, copy_string_to_raw
from rpython.rtyper.lltypesystem.rlist import LIST_OF
from rpython.rtyper.annlowlevel import llstr
from rpython.rlib.objectmodel import specialize, we_are_translated
from rpython.rlib import jit
from rpython.rlib.rgc import (resizable_list_supporting_raw_ptr,
nonmoving_raw_ptr_for_resizable_list,
ll_for_resizable_list)
from rpython.rlib.signature import signature
from rpython.rlib import types
from rpython.rlib import rawstorage
ALLOW_UNALIGNED_ACCESS = rawstorage.misaligned_is_fine
@specialize.ll()
def is_alignment_correct(TYPE, index):
if ALLOW_UNALIGNED_ACCESS:
return True
try:
rawstorage._check_alignment(TYPE, index)
except rawstorage.AlignmentError:
return False
else:
return True
class CannotRead(Exception):
"""
Exception raised by Buffer.typed_read in case it is not possible to
accomplish the request. This might be because it is not supported by the
specific type of buffer, or because of alignment issues.
"""
class CannotWrite(Exception):
"""
Raised by Buffer.typed_write in case it is not possible to accomplish the
request
"""
class Buffer(object):
"""
Base class for buffers of bytes.
Most probably, you do NOT want to use this as a lone base class, but
either inherit from RawBuffer or GCBuffer, so that you automatically get
the proper implementation of typed_read and typed_write.
"""
_attrs_ = ['readonly']
_immutable_ = True
def getlength(self):
"""Return the size in bytes."""
raise NotImplementedError
def __len__(self):
res = self.getlength()
assert res >= 0
return res
def as_str(self):
"Returns an interp-level string with the whole content of the buffer."
# May be overridden.
return self.getslice(0, 1, self.getlength())
def getitem(self, index):
"Returns the index'th character in the buffer."
raise NotImplementedError # Must be overriden. No bounds checks.
def __getitem__(self, i):
return self.getitem(i)
def getslice(self, start, step, size):
# May be overridden. No bounds checks.
lst = ['\x00'] * size
for i in range(size):
lst[i] = self.getitem(start)
start += step
return ''.join(lst)
@signature(types.any(), types.int(), types.int(), returns=types.str())
def __getslice__(self, start, stop):
return self.getslice(start, 1, min(stop, self.getlength()) - start)
def setitem(self, index, char):
"Write a character into the buffer."
raise NotImplementedError # Must be overriden. No bounds checks.
def __setitem__(self, i, char):
return self.setitem(i, char)
def setslice(self, start, string):
# May be overridden. No bounds checks.
for i in range(len(string)):
self.setitem(start + i, string[i])
@jit.look_inside_iff(lambda self, index, count:
jit.isconstant(count) and count <= 8)
def setzeros(self, index, count):
for i in range(index, index + count):
self.setitem(i, '\x00')
@specialize.ll_and_arg(1)
def typed_read(self, TP, byte_offset):
"""
Read the value of type TP starting at byte_offset. No bounds checks
"""
raise CannotRead
@specialize.ll_and_arg(1)
def typed_write(self, TP, byte_offset, value):
"""
Write the value of type TP at byte_offset. No bounds checks
"""
raise CannotWrite
def get_raw_address(self):
msg = "cannot take the raw address of this buffer"
if not we_are_translated():
msg += " '%s'" % (self,)
raise ValueError(msg)
class RawBuffer(Buffer):
"""
A buffer which is backed by a raw, non-movable memory area. It implementes
typed_read and typed_write in terms of get_raw_address(), llop.raw_load,
llop.raw_store.
NOTE: this assumes that get_raw_address() is cheap. Do not use this as a
base class if get_raw_address() is potentially costly, like for example if
you call rgc.nonmoving_raw_ptr_for_resizable_list
"""
_immutable_ = True
@specialize.ll_and_arg(1)
def typed_read(self, TP, byte_offset):
"""
Read the value of type TP starting at byte_offset. No bounds checks
"""
if not is_alignment_correct(TP, byte_offset):
raise CannotRead
ptr = self.get_raw_address()
return llop.raw_load(TP, ptr, byte_offset)
@specialize.ll_and_arg(1)
def typed_write(self, TP, byte_offset, value):
"""
Write the value of type TP at byte_offset. No bounds checks
"""
if self.readonly or not is_alignment_correct(TP, byte_offset):
raise CannotWrite
ptr = self.get_raw_address()
value = lltype.cast_primitive(TP, value)
return llop.raw_store(lltype.Void, ptr, byte_offset, value)
class LLBuffer(RawBuffer):
_immutable_ = True
def __init__(self, raw_cdata, size):
self.raw_cdata = raw_cdata
self.size = size
self.readonly = False
def getlength(self):
return self.size
def getitem(self, index):
return self.raw_cdata[index]
def setitem(self, index, char):
self.raw_cdata[index] = char
def get_raw_address(self):
return self.raw_cdata
def getslice(self, start, step, size):
if step == 1:
return rffi.charpsize2str(rffi.ptradd(self.raw_cdata, start), size)
return RawBuffer.getslice(self, start, step, size)
def setslice(self, start, string):
raw_cdata = rffi.ptradd(self.raw_cdata, start)
copy_string_to_raw(llstr(string), raw_cdata, 0, len(string))
class RawByteBuffer(RawBuffer):
_immutable_ = True
def __init__(self, length):
self._length = length
self._buf = lltype.malloc(rffi.CCHARP.TO, length, flavor='raw', zero=True)
self.readonly = False
def getlength(self):
return self._length
def getitem(self, index):
return self._buf[index]
def getslice(self, start, step, size):
if step == 1:
return rffi.charpsize2str(rffi.ptradd(self._buf, start), size)
return Buffer.getslice(self, start, step, size)
def setitem(self, index, char):
self._buf[index] = char
def get_raw_address(self):
return self._buf
def __del__(self):
lltype.free(self._buf, flavor='raw')
self._buf = lltype.nullptr(rffi.CCHARP.TO)
class GCBuffer(Buffer):
"""
Base class for a buffer which is backed by a GC-managed memory area. You
MUST also decorate the class with @GCBuffer.decorate: it implements
typed_read and typed_write in terms of llop.gc_load_indexed and
llop.gc_store_indexed.
"""
_attrs_ = ['readonly', 'value']
_immutable_ = True
@staticmethod
def decorate(targetcls):
"""
Create and attach specialized versions of typed_{read,write}. We need to
do this becase the JIT codewriters mandates that base_ofs is an
RPython constant.
"""
if targetcls.__bases__ != (GCBuffer,):
raise ValueError("@GCBuffer.decorate should be used only on "
"GCBuffer subclasses")
base_ofs = targetcls._get_gc_data_offset()
scale_factor = llmemory.sizeof(lltype.Char)
@specialize.ll_and_arg(1)
def typed_read(self, TP, byte_offset):
if not is_alignment_correct(TP, byte_offset):
raise CannotRead
lldata = self._get_gc_data()
byte_offset += self._get_gc_data_extra_offset()
return llop.gc_load_indexed(TP, lldata, byte_offset,
scale_factor, base_ofs)
@specialize.ll_and_arg(1)
def typed_write(self, TP, byte_offset, value):
if self.readonly or not is_alignment_correct(TP, byte_offset):
raise CannotWrite
lldata = self._get_gc_data()
byte_offset += self._get_gc_data_extra_offset()
value = lltype.cast_primitive(TP, value)
return llop.gc_store_indexed(lltype.Void, lldata, byte_offset, value,
scale_factor, base_ofs)
targetcls.typed_read = typed_read
targetcls.typed_write = typed_write
return targetcls
@staticmethod
def _get_gc_data_offset(self):
raise NotImplementedError
def _get_gc_data_extra_offset(self):
return 0
def _get_gc_data(self):
raise NotImplementedError
@specialize.ll_and_arg(1)
def typed_read(self, TP, byte_offset):
raise NotImplementedError("You MUST decorate this class with "
"@GCBuffer.decorate")
@specialize.ll_and_arg(1)
def typed_write(self, TP, byte_offset, value):
raise NotImplementedError("You MUST decorate this class with "
"@GCBuffer.decorate")
def get_gc_data_for_list_of_chars(data):
ll_data = ll_for_resizable_list(data)
ll_items = ll_data.items
return lltype.cast_opaque_ptr(llmemory.GCREF, ll_items)
def get_gc_data_offset_for_list_of_chars():
LIST = LIST_OF(lltype.Char)
return llmemory.itemoffsetof(LIST.items.TO, 0)
@GCBuffer.decorate
class ByteBuffer(GCBuffer):
_immutable_ = True
def __init__(self, n):
self.data = resizable_list_supporting_raw_ptr(['\0'] * n)
self.readonly = False
def getlength(self):
return len(self.data)
def getitem(self, index):
return self.data[index]
def setitem(self, index, char):
self.data[index] = char
def getslice(self, start, step, size):
if step == 1:
assert start >= 0
assert size >= 0
if start == 0 and size == len(self.data):
return "".join(self.data)
return "".join(self.data[start:start + size])
return Buffer.getslice(self, start, step, size)
def get_raw_address(self):
return nonmoving_raw_ptr_for_resizable_list(self.data)
def _get_gc_data(self):
return get_gc_data_for_list_of_chars(self.data)
@staticmethod
def _get_gc_data_offset():
return get_gc_data_offset_for_list_of_chars()
@GCBuffer.decorate
class StringBuffer(GCBuffer):
_attrs_ = ['readonly', 'value']
_immutable_ = True
def __init__(self, value):
assert value is not None
self.value = value
self.readonly = 1
def getlength(self):
return len(self.value)
def as_str(self):
return self.value
def getitem(self, index):
return self.value[index]
def getslice(self, start, step, size):
if size == 0:
return ""
if step == 1:
assert start >= 0
assert size >= 0
if start == 0 and size == len(self.value):
return self.value
return self.value[start:start + size]
return Buffer.getslice(self, start, step, size)
def get_raw_address(self):
from rpython.rtyper.lltypesystem import rffi
# may still raise ValueError on some GCs
return rffi.get_raw_address_of_string(self.value)
@staticmethod
def _get_gc_data_offset():
return (llmemory.offsetof(STR, 'chars') +
llmemory.itemoffsetof(STR.chars, 0))
def _get_gc_data(self):
lls = llstr(self.value)
return lltype.cast_opaque_ptr(llmemory.GCREF, lls)
class SubBuffer(Buffer):
_attrs_ = ['buffer', 'offset', 'size', 'readonly']
_immutable_ = True
@signature(types.any(), types.instance(Buffer), types.int(), types.int(),
returns=types.none())
def __init__(self, buffer, offset, size):
self.readonly = buffer.readonly
if isinstance(buffer, SubBuffer): # don't nest them
# we want a view (offset, size) over a view
# (buffer.offset, buffer.size) over buffer.buffer.
# Note that either '.size' can be -1 to mean 'up to the end'.
at_most = buffer.getlength() - offset
if size > at_most or size < 0:
if at_most < 0:
at_most = 0
size = at_most
offset += buffer.offset
buffer = buffer.buffer
#
self.buffer = buffer
self.offset = offset
self.size = size
def getlength(self):
at_most = self.buffer.getlength() - self.offset
if 0 <= self.size <= at_most:
return self.size
elif at_most >= 0:
return at_most
else:
return 0
def getitem(self, index):
return self.buffer.getitem(self.offset + index)
def getslice(self, start, step, size):
if size == 0:
# otherwise, adding self.offset might make them out of bounds
return ''
return self.buffer.getslice(self.offset + start, step, size)
def setitem(self, index, char):
self.buffer.setitem(self.offset + index, char)
def setslice(self, start, string):
if len(string) == 0:
# otherwise, adding self.offset might make 'start' out of bounds
return
self.buffer.setslice(self.offset + start, string)
def get_raw_address(self):
from rpython.rtyper.lltypesystem import rffi
ptr = self.buffer.get_raw_address()
return rffi.ptradd(ptr, self.offset)
@specialize.ll_and_arg(1)
def typed_read(self, TP, byte_offset):
return self.buffer.typed_read(TP, byte_offset + self.offset)
@specialize.ll_and_arg(1)
def typed_write(self, TP, byte_offset, value):
return self.buffer.typed_write(TP, byte_offset + self.offset, value)
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