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- #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 */
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