memory.py

# Helper functions dealing with memory blocks.

import ctypes as ct

def addressOffset(x, offset, bt):
  return ct.cast(ct.addressof(x.contents)+int(offset), ct.POINTER(bt))

def allocateMem(size):
  return ct.cast((ct.c_byte * max(0,size))(), ct.POINTER(ct.c_byte))

# Copy an array if its is not-None.  This is important for treating
# Numpy arrays as flat memory, but has some overhead.
def normaliseArray(x):
  if (x.base is x) or (x.base is None):
    return x
  else:
    return x.copy()

def unwrapArray(x):
  return normaliseArray(x).ctypes.data_as(ct.POINTER(ct.c_byte))

def createArray(x, dim):
  return np.ctypeslib.as_array(x, shape=dim)

def indexArray(x, offset, bt, nptype):
  return nptype(addressOffset(x, offset, bt)[0])

def writeScalarArray(x, offset, v):
  ct.memmove(ct.addressof(x.contents)+int(offset), ct.addressof(v), ct.sizeof(v))

# An opaque Futhark value.
class opaque(object):
  def __init__(self, desc, *payload):
    self.data = payload
    self.desc = desc

  def __repr__(self):
    return "<opaque Futhark value of type {}>".format(self.desc)