#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: - 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 digit; sdigit; /* signed variant of digit */ twodigits; stwodigits; /* signed variant of twodigits */ #define PyLong_SHIFT … #define _PyLong_DECIMAL_SHIFT … #define _PyLong_DECIMAL_BASE … #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 … #define _PyLong_DECIMAL_SHIFT … #define _PyLong_DECIMAL_BASE … #else #error "PYLONG_BITS_IN_DIGIT should be 15 or 30" #endif #define PyLong_BASE … #define PyLong_MASK … /* Long integer representation. Long integers are made up of a number of 30- or 15-bit digits, depending on the platform. The number of digits (ndigits) is stored in the high bits of the lv_tag field (lvtag >> _PyLong_NON_SIZE_BITS). The absolute value of a number is equal to SUM(for i=0 through ndigits-1) ob_digit[i] * 2**(PyLong_SHIFT*i) The sign of the value is stored in the lower 2 bits of lv_tag. - 0: Positive - 1: Zero - 2: Negative The third lowest bit of lv_tag is reserved for an immortality flag, but is not currently used. In a normalized number, ob_digit[ndigits-1] (the most significant digit) is never zero. Also, in all cases, for all valid i, 0 <= ob_digit[i] <= PyLong_MASK. The allocation function takes care of allocating extra memory so that ob_digit[0] ... ob_digit[ndigits-1] are actually available. We always allocate memory for at least one digit, so accessing ob_digit[0] is always safe. However, in the case ndigits == 0, the contents of ob_digit[0] may be undefined. */ _PyLongValue; struct _longobject { … }; PyAPI_FUNC(PyLongObject*) _PyLong_New(Py_ssize_t); // Return a copy of src. PyAPI_FUNC(PyObject*) _PyLong_Copy(PyLongObject *src); PyAPI_FUNC(PyLongObject*) _PyLong_FromDigits( int negative, Py_ssize_t digit_count, digit *digits); /* Inline some internals for speed. These should be in pycore_long.h * if user code didn't need them inlined. */ #define _PyLong_SIGN_MASK … #define _PyLong_NON_SIZE_BITS … static inline int _PyLong_IsCompact(const PyLongObject* op) { … } #define PyUnstable_Long_IsCompact … static inline Py_ssize_t _PyLong_CompactValue(const PyLongObject *op) { … } #define PyUnstable_Long_CompactValue … #ifdef __cplusplus } #endif #endif /* !Py_LONGINTREPR_H */ #endif /* Py_LIMITED_API */
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