globalmem.py

   1 #Copyright (c) 2008 Vincent Povirk
   2 #
   3 #Permission is hereby granted, free of charge, to any person
   4 #obtaining a copy of this software and associated documentation
   5 #files (the "Software"), to deal in the Software without
   6 #restriction, including without limitation the rights to use,
   7 #copy, modify, merge, publish, distribute, sublicense, and/or sell
   8 #copies of the Software, and to permit persons to whom the
   9 #Software is furnished to do so, subject to the following
  10 #conditions:
  11 #
  12 #The above copyright notice and this permission notice shall be
  13 #included in all copies or substantial portions of the Software.
  14 #
  15 #THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16 #EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  17 #OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18 #NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  19 #HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  20 #WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21 #FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  22 #OTHER DEALINGS IN THE SOFTWARE.
  23
  24 # Global memory definitions
  25 # see http://msdn.microsoft.com/en-us/library/aa366596(VS.85).aspx
  26
  27 from ctypes import windll, WinError
  28 from winliteutils import get_symbols, NONZERO, ZERO
  29 from windef import UINT, SIZE_T, HGLOBAL, LPCVOID, LPVOID
  30
  31 _kernel32 = windll.kernel32
  32
  33 GMEM_FIXED = 0x0000
  34 GMEM_MOVEABLE = 0x0002
  35 GMEM_NOCOMPACT = 0x0010
  36 GMEM_NODISCARD = 0x0020
  37 GMEM_ZEROINIT = 0x0040
  38 GMEM_MODIFY = 0x0080
  39 GMEM_DISCARDABLE = 0x0100
  40 GMEM_NOT_BANKED = 0x1000
  41 GMEM_SHARE = 0x2000
  42 GMEM_DDESHARE = 0x2000
  43 GMEM_NOTIFY = 0x4000
  44 GMEM_LOWER = GMEM_NOT_BANKED
  45 GMEM_DISCARDED = 0x4000
  46 GMEM_LOCKCOUNT = 0x00ff
  47 GMEM_INVALID_HANDLE = 0x8000
  48
  49 GHND = (GMEM_MOVEABLE | GMEM_ZEROINIT)
  50 GPTR = (GMEM_FIXED | GMEM_ZEROINIT)
  51
  52 def gmem_handle(x):
  53     if x == GMEM_INVALID_HANDLE:
  54         raise WinError()
  55     return x
  56
  57 get_symbols(globals(), _kernel32, ['GlobalAlloc', 'GlobalFlags', 'GlobalFree', 'GlobalHandle', 'GlobalLock', 'GlobalReAlloc', 'GlobalSize', 'GlobalUnlock'])
  58
  59 GlobalAlloc.argtypes = [UINT, SIZE_T]
  60 GlobalAlloc.restype = NONZERO
  61
  62 GlobalFlags.argtypes = [HGLOBAL]
  63 GlobalFlags.restype = gmem_handle
  64
  65 GlobalFree.argtypes = [HGLOBAL]
  66 GlobalFree.restype = ZERO
  67
  68 GlobalHandle.argtypes = [LPCVOID]
  69 GlobalHandle.restype = NONZERO
  70
  71 GlobalLock.argtypes = [HGLOBAL]
  72 GlobalLock.restype = NONZERO
  73
  74 GlobalReAlloc.argtypes = [HGLOBAL, SIZE_T, UINT]
  75 GlobalReAlloc.restype = NONZERO
  76
  77 GlobalSize.argtypes = [HGLOBAL]
  78 GlobalSize.restype = NONZERO
  79
  80 GlobalUnlock.argtypes = [HGLOBAL]
  81 GlobalUnlock.restype = NONZERO
  82
  83 #obsolete:
  84 #GlobalLRUNewest = lambda x: x
  85 #GlobalLRUOldest = lambda x: x
  86
  87 def GlobalDiscard(handle):
  88     return GlobalReAlloc(handle, 0, GMEM_MOVEABLE)
  89
  90 class GlobalMemoryObject(object):
  91     __slots__ = ['handle', 'needs_free', '_as_parameter_']
  92
  93     def __init__(self, flags=GMEM_MOVEABLE, size=0, handle=None, needs_free=True):
  94         if handle is None:
  95             handle = GlobalAlloc(flags, size)
  96         self.handle = self._as_parameter_ = handle
  97         self.needs_free = needs_free
  98
  99     def free(self):
 100         if self.needs_free:
 101             if GlobalFree(self) != 0:
 102                 raise WinError()
 103             self.needs_free = False
 104             self.handle = self._as_parameter_ = 0
 105
 106     def lock(self):
 107         return GlobalLock(self)
 108
 109     def unlock(self):
 110         GlobalUnlock(self)
 111
 112     def __enter__(self):
 113         return self.lock()
 114
 115     def __exit__(self, exc_type, exc_val, exc_tb):
 116         self.unlock()
 117
 118     def realloc(self, size, flags=GMEM_MOVEABLE):
 119         GlobalReAlloc(self, size, flags)
 120
 121     def discard(self):
 122         GlobalDiscard(self)
 123
 124     def get_flags(self):
 125         return GlobalFlags(self)
 126
 127     def get_size(self):
 128         return GlobalSize(self)
 129
 130     def __del__(self):
 131         self.free()
 132