diff options
Diffstat (limited to 'Include/objimpl.h')
| -rw-r--r-- | Include/objimpl.h | 52 |
1 files changed, 24 insertions, 28 deletions
diff --git a/Include/objimpl.h b/Include/objimpl.h index 2ea3ad5..db4cb6d 100644 --- a/Include/objimpl.h +++ b/Include/objimpl.h @@ -173,40 +173,36 @@ extern DL_IMPORT(void) _PyObject_Del(PyObject *); #define _PyObject_SIZE(typeobj) ( (typeobj)->tp_basicsize ) -/* _PyObject_VAR_SIZE computes the amount of memory allocated for a vrbl- - size object with nitems items, exclusive of gc overhead (if any). The - value is rounded up to the closest multiple of sizeof(void *), in order - to ensure that pointer fields at the end of the object are correctly - aligned for the platform (this is of special importance for subclasses - of, e.g., str or long, so that pointers can be stored after the embedded - data). - - Note that there's no memory wastage in doing this, as malloc has to - return (at worst) pointer-aligned memory anyway - - However, writing the macro to *return* the result is clumsy due to the - calculations needed. Instead you must pass the result lvalue as the first - argument, and it should be of type size_t (both because that's the - correct conceptual type, and because using an unsigned type allows the - compiler to generate faster code for the mod computation inside the - macro). +/* _PyObject_VAR_SIZE returns the number of bytes (as size_t) allocated for a + vrbl-size object with nitems items, exclusive of gc overhead (if any). The + value is rounded up to the closest multiple of sizeof(void *), in order to + ensure that pointer fields at the end of the object are correctly aligned + for the platform (this is of special importance for subclasses of, e.g., + str or long, so that pointers can be stored after the embedded data). + + Note that there's no memory wastage in doing this, as malloc has to + return (at worst) pointer-aligned memory anyway. */ -#define _PyObject_VAR_SIZE(result, typeobj, nitems) \ - do { \ - size_t mod; \ - (result) = (size_t) (typeobj)->tp_basicsize; \ - (result) += (size_t) ((nitems)*(typeobj)->tp_itemsize); \ - mod = (result) % SIZEOF_VOID_P; \ - if (mod) \ - (result) += SIZEOF_VOID_P - mod; \ - } while(0) +#if ((SIZEOF_VOID_P - 1) & SIZEOF_VOID_P) != 0 +# error "_PyObject_VAR_SIZE requires SIZEOF_VOID_P be a power of 2" +#endif + +#define _PyObject_VAR_SIZE(typeobj, nitems) \ + (size_t) \ + ( ( (typeobj)->tp_basicsize + \ + (nitems)*(typeobj)->tp_itemsize + \ + (SIZEOF_VOID_P - 1) \ + ) & ~(SIZEOF_VOID_P - 1) \ + ) #define PyObject_NEW(type, typeobj) \ ( (type *) PyObject_Init( \ (PyObject *) PyObject_MALLOC( _PyObject_SIZE(typeobj) ), (typeobj)) ) -#define PyObject_NEW_VAR(type, typeobj, nitems) \ - ((type *) _PyObject_NewVar(typeobj, nitems)) +#define PyObject_NEW_VAR(type, typeobj, n) \ +( (type *) PyObject_InitVar( \ + (PyVarObject *) PyObject_MALLOC(_PyObject_VAR_SIZE((typeobj),(n)) ),\ + (typeobj), (n)) ) #define PyObject_DEL(op) PyObject_FREE(op) |