projects / OpenSPARC-T2-SAM / blame
| Commit | Line | Data |
|---|---|---|
| 920dae64 AT |
1 | #ifndef Py_LONGINTREPR_H |
| 2 | #define Py_LONGINTREPR_H | |
| 3 | #ifdef __cplusplus | |
| 4 | extern "C" { | |
| 5 | #endif | |
| 6 | ||
| 7 | ||
| 8 | /* This is published for the benefit of "friend" marshal.c only. */ | |
| 9 | ||
| 10 | /* Parameters of the long integer representation. | |
| 11 | These shouldn't have to be changed as C should guarantee that a short | |
| 12 | contains at least 16 bits, but it's made changeable anyway. | |
| 13 | Note: 'digit' should be able to hold 2*MASK+1, and 'twodigits' | |
| 14 | should be able to hold the intermediate results in 'mul' | |
| 15 | (at most (BASE-1)*(2*BASE+1) == MASK*(2*MASK+3)). | |
| 16 | Also, x_sub assumes that 'digit' is an unsigned type, and overflow | |
| 17 | is handled by taking the result mod 2**N for some N > SHIFT. | |
| 18 | And, at some places it is assumed that MASK fits in an int, as well. | |
| 19 | long_pow() requires that SHIFT be divisible by 5. */ | |
| 20 | ||
| 21 | typedef unsigned short digit; | |
| 22 | typedef unsigned int wdigit; /* digit widened to parameter size */ | |
| 23 | #define BASE_TWODIGITS_TYPE long | |
| 24 | typedef unsigned BASE_TWODIGITS_TYPE twodigits; | |
| 25 | typedef BASE_TWODIGITS_TYPE stwodigits; /* signed variant of twodigits */ | |
| 26 | ||
| 27 | #define SHIFT 15 | |
| 28 | #define BASE ((digit)1 << SHIFT) | |
| 29 | #define MASK ((int)(BASE - 1)) | |
| 30 | ||
| 31 | #if SHIFT % 5 != 0 | |
| 32 | #error "longobject.c requires that SHIFT be divisible by 5" | |
| 33 | #endif | |
| 34 | ||
| 35 | /* Long integer representation. | |
| 36 | The absolute value of a number is equal to | |
| 37 | SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i) | |
| 38 | Negative numbers are represented with ob_size < 0; | |
| 39 | zero is represented by ob_size == 0. | |
| 40 | In a normalized number, ob_digit[abs(ob_size)-1] (the most significant | |
| 41 | digit) is never zero. Also, in all cases, for all valid i, | |
| 42 | 0 <= ob_digit[i] <= MASK. | |
| 43 | The allocation function takes care of allocating extra memory | |
| 44 | so that ob_digit[0] ... ob_digit[abs(ob_size)-1] are actually available. | |
| 45 | ||
| 46 | CAUTION: Generic code manipulating subtypes of PyVarObject has to | |
| 47 | aware that longs abuse ob_size's sign bit. | |
| 48 | */ | |
| 49 | ||
| 50 | struct _longobject { | |
| 51 | PyObject_VAR_HEAD | |
| 52 | digit ob_digit[1]; | |
| 53 | }; | |
| 54 | ||
| 55 | PyAPI_FUNC(PyLongObject *) _PyLong_New(int); | |
| 56 | ||
| 57 | /* Return a copy of src. */ | |
| 58 | PyAPI_FUNC(PyObject *) _PyLong_Copy(PyLongObject *src); | |
| 59 | ||
| 60 | #ifdef __cplusplus | |
| 61 | } | |
| 62 | #endif | |
| 63 | #endif /* !Py_LONGINTREPR_H */ |