mirror of
https://github.com/python/cpython.git
synced 2024-11-30 10:41:14 +01:00
100 lines
3.7 KiB
C
100 lines
3.7 KiB
C
#ifndef Py_LIMITED_API
|
|
#ifndef Py_LONGINTREPR_H
|
|
#define Py_LONGINTREPR_H
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
|
|
/* This is published for the benefit of "friends" marshal.c and _decimal.c. */
|
|
|
|
/* Parameters of the integer representation. There are two different
|
|
sets of parameters: one set for 30-bit digits, stored in an unsigned 32-bit
|
|
integer type, and one set for 15-bit digits with each digit stored in an
|
|
unsigned short. The value of PYLONG_BITS_IN_DIGIT, defined either at
|
|
configure time or in pyport.h, is used to decide which digit size to use.
|
|
|
|
Type 'digit' should be able to hold 2*PyLong_BASE-1, and type 'twodigits'
|
|
should be an unsigned integer type able to hold all integers up to
|
|
PyLong_BASE*PyLong_BASE-1. x_sub assumes that 'digit' is an unsigned type,
|
|
and that overflow is handled by taking the result modulo 2**N for some N >
|
|
PyLong_SHIFT. The majority of the code doesn't care about the precise
|
|
value of PyLong_SHIFT, but there are some notable exceptions:
|
|
|
|
- long_pow() requires that PyLong_SHIFT be divisible by 5
|
|
|
|
- PyLong_{As,From}ByteArray require that PyLong_SHIFT be at least 8
|
|
|
|
- long_hash() requires that PyLong_SHIFT is *strictly* less than the number
|
|
of bits in an unsigned long, as do the PyLong <-> long (or unsigned long)
|
|
conversion functions
|
|
|
|
- the Python int <-> size_t/Py_ssize_t conversion functions expect that
|
|
PyLong_SHIFT is strictly less than the number of bits in a size_t
|
|
|
|
- the marshal code currently expects that PyLong_SHIFT is a multiple of 15
|
|
|
|
- NSMALLNEGINTS and NSMALLPOSINTS should be small enough to fit in a single
|
|
digit; with the current values this forces PyLong_SHIFT >= 9
|
|
|
|
The values 15 and 30 should fit all of the above requirements, on any
|
|
platform.
|
|
*/
|
|
|
|
#if PYLONG_BITS_IN_DIGIT == 30
|
|
typedef uint32_t digit;
|
|
typedef int32_t sdigit; /* signed variant of digit */
|
|
typedef uint64_t twodigits;
|
|
typedef int64_t stwodigits; /* signed variant of twodigits */
|
|
#define PyLong_SHIFT 30
|
|
#define _PyLong_DECIMAL_SHIFT 9 /* max(e such that 10**e fits in a digit) */
|
|
#define _PyLong_DECIMAL_BASE ((digit)1000000000) /* 10 ** DECIMAL_SHIFT */
|
|
#elif PYLONG_BITS_IN_DIGIT == 15
|
|
typedef unsigned short digit;
|
|
typedef short sdigit; /* signed variant of digit */
|
|
typedef unsigned long twodigits;
|
|
typedef long stwodigits; /* signed variant of twodigits */
|
|
#define PyLong_SHIFT 15
|
|
#define _PyLong_DECIMAL_SHIFT 4 /* max(e such that 10**e fits in a digit) */
|
|
#define _PyLong_DECIMAL_BASE ((digit)10000) /* 10 ** DECIMAL_SHIFT */
|
|
#else
|
|
#error "PYLONG_BITS_IN_DIGIT should be 15 or 30"
|
|
#endif
|
|
#define PyLong_BASE ((digit)1 << PyLong_SHIFT)
|
|
#define PyLong_MASK ((digit)(PyLong_BASE - 1))
|
|
|
|
#if PyLong_SHIFT % 5 != 0
|
|
#error "longobject.c requires that PyLong_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 ints 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 */
|
|
#endif /* Py_LIMITED_API */
|