Commit 5ecfc44d authored by Dag Sverre Seljebotn's avatar Dag Sverre Seljebotn

Buffers: cast option (#76)

Yet more really low-hanging fruit...
parent b9ffa8b7
......@@ -113,8 +113,8 @@ class IntroduceBufferAuxiliaryVars(CythonTransform):
#
# Analysis
#
buffer_options = ("dtype", "ndim", "mode", "negative_indices") # ordered!
buffer_defaults = {"ndim": 1, "mode": "full", "negative_indices": True}
buffer_options = ("dtype", "ndim", "mode", "negative_indices", "cast") # ordered!
buffer_defaults = {"ndim": 1, "mode": "full", "negative_indices": True, "cast": False}
buffer_positional_options_count = 1 # anything beyond this needs keyword argument
ERR_BUF_OPTION_UNKNOWN = '"%s" is not a buffer option'
......@@ -124,7 +124,7 @@ ERR_BUF_MISSING = '"%s" missing'
ERR_BUF_MODE = 'Only allowed buffer modes are: "c", "fortran", "full", "strided" (as a compile-time string)'
ERR_BUF_NDIM = 'ndim must be a non-negative integer'
ERR_BUF_DTYPE = 'dtype must be "object", numeric type or a struct'
ERR_BUF_NEGATIVE_INDICES = 'negative_indices must be a boolean'
ERR_BUF_BOOL = '"%s" must be a boolean'
def analyse_buffer_options(globalpos, env, posargs, dictargs, defaults=None, need_complete=True):
"""
......@@ -179,9 +179,13 @@ def analyse_buffer_options(globalpos, env, posargs, dictargs, defaults=None, nee
if mode and not (mode in ('full', 'strided', 'c', 'fortran')):
raise CompileError(globalpos, ERR_BUF_MODE)
negative_indices = options.get("negative_indices")
if mode and not isinstance(negative_indices, bool):
raise CompileError(globalpos, ERR_BUF_NEGATIVE_INDICES)
def assert_bool(name):
x = options.get(name)
if not isinstance(x, bool):
raise CompileError(globalpos, ERR_BUF_BOOL % name)
assert_bool('negative_indices')
assert_bool('cast')
return options
......@@ -234,13 +238,15 @@ def put_acquire_arg_buffer(entry, code, pos):
code.globalstate.use_utility_code(acquire_utility_code)
buffer_aux = entry.buffer_aux
getbuffer_cname = get_getbuffer_code(entry.type.dtype, code)
# Acquire any new buffer
code.putln(code.error_goto_if("%s((PyObject*)%s, &%s, %s, %d) == -1" % (
code.putln(code.error_goto_if("%s((PyObject*)%s, &%s, %s, %d, %d) == -1" % (
getbuffer_cname,
entry.cname,
entry.buffer_aux.buffer_info_var.cname,
get_flags(buffer_aux, entry.type),
entry.type.ndim), pos))
entry.type.ndim,
int(entry.type.cast)), pos))
# An exception raised in arg parsing cannot be catched, so no
# need to care about the buffer then.
put_unpack_buffer_aux_into_scope(buffer_aux, entry.type.mode, code)
......@@ -274,11 +280,12 @@ def put_assign_to_buffer(lhs_cname, rhs_cname, buffer_aux, buffer_type,
bufstruct = buffer_aux.buffer_info_var.cname
flags = get_flags(buffer_aux, buffer_type)
getbuffer = "%s((PyObject*)%%s, &%s, %s, %d)" % (get_getbuffer_code(buffer_type.dtype, code),
getbuffer = "%s((PyObject*)%%s, &%s, %s, %d, %d)" % (get_getbuffer_code(buffer_type.dtype, code),
# note: object is filled in later (%%s)
bufstruct,
flags,
buffer_type.ndim)
buffer_type.ndim,
int(buffer_type.cast))
if is_initialized:
# Release any existing buffer
......@@ -572,10 +579,11 @@ def get_getbuffer_code(dtype, code):
if not code.globalstate.has_utility_code(name):
code.globalstate.use_utility_code(acquire_utility_code)
itemchecker = get_ts_check_item(dtype, code)
dtype_cname = dtype.declaration_code("")
utilcode = [dedent("""
static int %s(PyObject* obj, Py_buffer* buf, int flags, int nd); /*proto*/
static int %s(PyObject* obj, Py_buffer* buf, int flags, int nd, int cast); /*proto*/
""") % name, dedent("""
static int %(name)s(PyObject* obj, Py_buffer* buf, int flags, int nd) {
static int %(name)s(PyObject* obj, Py_buffer* buf, int flags, int nd, int cast) {
const char* ts;
if (obj == Py_None) {
__Pyx_ZeroBuffer(buf);
......@@ -587,6 +595,7 @@ def get_getbuffer_code(dtype, code):
__Pyx_BufferNdimError(buf, nd);
goto fail;
}
if (!cast) {
ts = buf->format;
ts = __Pyx_ConsumeWhitespace(ts);
if (!ts) goto fail;
......@@ -599,6 +608,13 @@ def get_getbuffer_code(dtype, code):
"Expected non-struct buffer data type (expected end, got '%%s')", ts);
goto fail;
}
} else {
if (buf->itemsize != sizeof(%(dtype_cname)s)) {
PyErr_SetString(PyExc_ValueError,
"Attempted cast of buffer to datatype of different size.");
goto fail;
}
}
if (buf->suboffsets == NULL) buf->suboffsets = __Pyx_minusones;
return 0;
fail:;
......
......@@ -200,18 +200,21 @@ class BufferType(BaseType):
# dtype PyrexType
# ndim int
# mode str
# is_buffer boolean
# writable boolean
# negative_indices bool
# cast bool
# is_buffer bool
# writable bool
is_buffer = 1
writable = True
def __init__(self, base, dtype, ndim, mode, negative_indices):
def __init__(self, base, dtype, ndim, mode, negative_indices, cast):
self.base = base
self.dtype = dtype
self.ndim = ndim
self.buffer_ptr_type = CPtrType(dtype)
self.mode = mode
self.negative_indices = negative_indices
self.cast = cast
def as_argument_type(self):
return self
......
......@@ -943,7 +943,32 @@ def assign_to_object(object[object] buf, int idx, obj):
"""
buf[idx] = obj
#
# cast option
#
@testcase
def buffer_cast(object[unsigned int, cast=True] buf, int idx):
"""
Round-trip a signed int through unsigned int buffer access.
>>> A = IntMockBuffer(None, [-100])
>>> buffer_cast(A, 0)
-100
"""
cdef unsigned int data = buf[idx]
return <int>data
@testcase
def buffer_cast_fails(object[char, cast=True] buf):
"""
Cannot cast between datatype of different sizes.
>>> buffer_cast_fails(IntMockBuffer(None, [0]))
Traceback (most recent call last):
...
ValueError: Attempted cast of buffer to datatype of different size.
"""
return buf[0]
#
......@@ -1101,6 +1126,13 @@ cdef class MockBuffer:
cdef get_default_format(self):
print "ERROR, not subclassed", self.__class__
cdef class CharMockBuffer(MockBuffer):
cdef int write(self, char* buf, object value) except -1:
(<char*>buf)[0] = <int>value
return 0
cdef get_itemsize(self): return sizeof(char)
cdef get_default_format(self): return b"@b"
cdef class IntMockBuffer(MockBuffer):
cdef int write(self, char* buf, object value) except -1:
(<int*>buf)[0] = <int>value
......
......@@ -138,6 +138,13 @@ try:
...
ValueError: only objects, int and float dtypes supported for ndarray buffer access so far (dtype is 20)
>>> test_good_cast()
True
>>> test_bad_cast()
Traceback (most recent call last):
...
ValueError: Attempted cast of buffer to datatype of different size.
"""
except:
__doc__ = ""
......@@ -225,3 +232,15 @@ def test_dtype(dtype, inc1):
a = np.array([0, 10], dtype=dtype)
inc1(a)
if a[1] != 11: print "failed!"
def test_good_cast():
# Check that a signed int can round-trip through casted unsigned int access
cdef np.ndarray[unsigned int, cast=True] arr = np.array([-100], dtype='i')
cdef unsigned int data = arr[0]
return -100 == <int>data
def test_bad_cast():
# This should raise an exception
cdef np.ndarray[long, cast=True] arr = np.array([1], dtype='b')
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