1#ifndef Py_INTERNAL_LONG_H
2#define Py_INTERNAL_LONG_H
3#ifdef __cplusplus
4extern "C" {
5#endif
6
7#ifndef Py_BUILD_CORE
8#  error "this header requires Py_BUILD_CORE define"
9#endif
10
11#include "pycore_global_objects.h"  // _PY_NSMALLNEGINTS
12#include "pycore_runtime.h"       // _PyRuntime
13
14/*
15 * Default int base conversion size limitation: Denial of Service prevention.
16 *
17 * Chosen such that this isn't wildly slow on modern hardware and so that
18 * everyone's existing deployed numpy test suite passes before
19 * https://github.com/numpy/numpy/issues/22098 is widely available.
20 *
21 * $ python -m timeit -s 's = "1"*4300' 'int(s)'
22 * 2000 loops, best of 5: 125 usec per loop
23 * $ python -m timeit -s 's = "1"*4300; v = int(s)' 'str(v)'
24 * 1000 loops, best of 5: 311 usec per loop
25 * (zen2 cloud VM)
26 *
27 * 4300 decimal digits fits a ~14284 bit number.
28 */
29#define _PY_LONG_DEFAULT_MAX_STR_DIGITS 4300
30/*
31 * Threshold for max digits check.  For performance reasons int() and
32 * int.__str__() don't checks values that are smaller than this
33 * threshold.  Acts as a guaranteed minimum size limit for bignums that
34 * applications can expect from CPython.
35 *
36 * % python -m timeit -s 's = "1"*640; v = int(s)' 'str(int(s))'
37 * 20000 loops, best of 5: 12 usec per loop
38 *
39 * "640 digits should be enough for anyone." - gps
40 * fits a ~2126 bit decimal number.
41 */
42#define _PY_LONG_MAX_STR_DIGITS_THRESHOLD 640
43
44#if ((_PY_LONG_DEFAULT_MAX_STR_DIGITS != 0) && \
45   (_PY_LONG_DEFAULT_MAX_STR_DIGITS < _PY_LONG_MAX_STR_DIGITS_THRESHOLD))
46# error "_PY_LONG_DEFAULT_MAX_STR_DIGITS smaller than threshold."
47#endif
48
49
50/* runtime lifecycle */
51
52extern PyStatus _PyLong_InitTypes(PyInterpreterState *);
53extern void _PyLong_FiniTypes(PyInterpreterState *interp);
54
55
56/* other API */
57
58#define _PyLong_SMALL_INTS _Py_SINGLETON(small_ints)
59
60// _PyLong_GetZero() and _PyLong_GetOne() must always be available
61// _PyLong_FromUnsignedChar must always be available
62#if _PY_NSMALLPOSINTS < 257
63#  error "_PY_NSMALLPOSINTS must be greater than or equal to 257"
64#endif
65
66// Return a borrowed reference to the zero singleton.
67// The function cannot return NULL.
68static inline PyObject* _PyLong_GetZero(void)
69{ return (PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS]; }
70
71// Return a borrowed reference to the one singleton.
72// The function cannot return NULL.
73static inline PyObject* _PyLong_GetOne(void)
74{ return (PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS+1]; }
75
76static inline PyObject* _PyLong_FromUnsignedChar(unsigned char i)
77{
78    return Py_NewRef((PyObject *)&_PyLong_SMALL_INTS[_PY_NSMALLNEGINTS+i]);
79}
80
81PyObject *_PyLong_Add(PyLongObject *left, PyLongObject *right);
82PyObject *_PyLong_Multiply(PyLongObject *left, PyLongObject *right);
83PyObject *_PyLong_Subtract(PyLongObject *left, PyLongObject *right);
84
85/* Used by Python/mystrtoul.c, _PyBytes_FromHex(),
86   _PyBytes_DecodeEscape(), etc. */
87PyAPI_DATA(unsigned char) _PyLong_DigitValue[256];
88
89/* Format the object based on the format_spec, as defined in PEP 3101
90   (Advanced String Formatting). */
91PyAPI_FUNC(int) _PyLong_FormatAdvancedWriter(
92    _PyUnicodeWriter *writer,
93    PyObject *obj,
94    PyObject *format_spec,
95    Py_ssize_t start,
96    Py_ssize_t end);
97
98PyAPI_FUNC(int) _PyLong_FormatWriter(
99    _PyUnicodeWriter *writer,
100    PyObject *obj,
101    int base,
102    int alternate);
103
104PyAPI_FUNC(char*) _PyLong_FormatBytesWriter(
105    _PyBytesWriter *writer,
106    char *str,
107    PyObject *obj,
108    int base,
109    int alternate);
110
111#ifdef __cplusplus
112}
113#endif
114#endif /* !Py_INTERNAL_LONG_H */
115