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cpython/Include/longintrepr.h
Tim Peters 64b5ce3a69 SF bug #460020: bug or feature: unicode() and subclasses.
Given an immutable type M, and an instance I of a subclass of M, the
constructor call M(I) was just returning I as-is; but it should return a
new instance of M.  This fixes it for M in {int, long}.  Strings, floats
and tuples remain to be done.
Added new macros PyInt_CheckExact and PyLong_CheckExact, to more easily
distinguish between "is" and "is a" (i.e., only an int passes
PyInt_CheckExact, while any sublass of int passes PyInt_Check).
Added private API function _PyLong_Copy.
2001-09-10 20:52:51 +00:00

56 lines
1.8 KiB
C

#ifndef Py_LONGINTREPR_H
#define Py_LONGINTREPR_H
#ifdef __cplusplus
extern "C" {
#endif
/* This is published for the benefit of "friend" marshal.c only. */
/* Parameters of the long integer representation.
These shouldn't have to be changed as C should guarantee that a short
contains at least 16 bits, but it's made changeable anyway.
Note: 'digit' should be able to hold 2*MASK+1, and 'twodigits'
should be able to hold the intermediate results in 'mul'
(at most MASK << SHIFT).
Also, x_sub assumes that 'digit' is an unsigned type, and overflow
is handled by taking the result mod 2**N for some N > SHIFT.
And, at some places it is assumed that MASK fits in an int, as well. */
typedef unsigned short digit;
typedef unsigned int wdigit; /* digit widened to parameter size */
#define BASE_TWODIGITS_TYPE long
typedef unsigned BASE_TWODIGITS_TYPE twodigits;
typedef BASE_TWODIGITS_TYPE stwodigits; /* signed variant of twodigits */
#define SHIFT 15
#define BASE ((digit)1 << SHIFT)
#define MASK ((int)(BASE - 1))
/* Long integer representation.
The absolute value of a number is equal to
SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
Negative numbers are represented with ob_size < 0;
zero is represented by ob_size == 0.
In a normalized number, ob_digit[abs(ob_size)-1] (the most significant
digit) is never zero. Also, in all cases, for all valid i,
0 <= ob_digit[i] <= MASK.
The allocation function takes care of allocating extra memory
so that ob_digit[0] ... ob_digit[abs(ob_size)-1] are actually available. */
struct _longobject {
PyObject_HEAD
int ob_size;
digit ob_digit[1];
};
DL_IMPORT(PyLongObject *) _PyLong_New(int);
/* Return a copy of src. */
DL_IMPORT(PyObject *) _PyLong_Copy(PyLongObject *src);
#ifdef __cplusplus
}
#endif
#endif /* !Py_LONGINTREPR_H */