| #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 (BASE-1)*(2*BASE+1) == MASK*(2*MASK+3)). |
| 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. |
| long_pow() requires that SHIFT be divisible by 5. */ |
| |
| typedef unsigned short digit; |
| typedef short sdigit; /* signed variant of digit */ |
| #define BASE_TWODIGITS_TYPE long |
| typedef unsigned BASE_TWODIGITS_TYPE twodigits; |
| typedef BASE_TWODIGITS_TYPE stwodigits; /* signed variant of twodigits */ |
| |
| #define PyLong_SHIFT 15 |
| #define PyLong_BASE ((digit)1 << PyLong_SHIFT) |
| #define PyLong_MASK ((digit)(PyLong_BASE - 1)) |
| |
| #if PyLong_SHIFT % 5 != 0 |
| #error "longobject.c requires that SHIFT be divisible by 5" |
| #endif |
| |
| /* 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. |
| |
| CAUTION: Generic code manipulating subtypes of PyVarObject has to |
| aware that longs abuse ob_size's sign bit. |
| */ |
| |
| struct _longobject { |
| PyObject_VAR_HEAD |
| digit ob_digit[1]; |
| }; |
| |
| PyAPI_FUNC(PyLongObject *) _PyLong_New(Py_ssize_t); |
| |
| /* Return a copy of src. */ |
| PyAPI_FUNC(PyObject *) _PyLong_Copy(PyLongObject *src); |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| #endif /* !Py_LONGINTREPR_H */ |