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The C and C++ Include Header Files

/usr/include/python3.12/cpython/longintrepr.h


$ cat -n /usr/include/python3.12/cpython/longintrepr.h

     1	#ifndef Py_LIMITED_API
     2	#ifndef Py_LONGINTREPR_H
     3	#define Py_LONGINTREPR_H
     4	#ifdef __cplusplus
     5	extern "C" {
     6	#endif
     7	
     8	
     9	/* This is published for the benefit of "friends" marshal.c and _decimal.c. */
    10	
    11	/* Parameters of the integer representation.  There are two different
    12	   sets of parameters: one set for 30-bit digits, stored in an unsigned 32-bit
    13	   integer type, and one set for 15-bit digits with each digit stored in an
    14	   unsigned short.  The value of PYLONG_BITS_IN_DIGIT, defined either at
    15	   configure time or in pyport.h, is used to decide which digit size to use.
    16	
    17	   Type 'digit' should be able to hold 2*PyLong_BASE-1, and type 'twodigits'
    18	   should be an unsigned integer type able to hold all integers up to
    19	   PyLong_BASE*PyLong_BASE-1.  x_sub assumes that 'digit' is an unsigned type,
    20	   and that overflow is handled by taking the result modulo 2**N for some N >
    21	   PyLong_SHIFT.  The majority of the code doesn't care about the precise
    22	   value of PyLong_SHIFT, but there are some notable exceptions:
    23	
    24	   - PyLong_{As,From}ByteArray require that PyLong_SHIFT be at least 8
    25	
    26	   - long_hash() requires that PyLong_SHIFT is *strictly* less than the number
    27	     of bits in an unsigned long, as do the PyLong <-> long (or unsigned long)
    28	     conversion functions
    29	
    30	   - the Python int <-> size_t/Py_ssize_t conversion functions expect that
    31	     PyLong_SHIFT is strictly less than the number of bits in a size_t
    32	
    33	   - the marshal code currently expects that PyLong_SHIFT is a multiple of 15
    34	
    35	   - NSMALLNEGINTS and NSMALLPOSINTS should be small enough to fit in a single
    36	     digit; with the current values this forces PyLong_SHIFT >= 9
    37	
    38	  The values 15 and 30 should fit all of the above requirements, on any
    39	  platform.
    40	*/
    41	
    42	#if PYLONG_BITS_IN_DIGIT == 30
    43	typedef uint32_t digit;
    44	typedef int32_t sdigit; /* signed variant of digit */
    45	typedef uint64_t twodigits;
    46	typedef int64_t stwodigits; /* signed variant of twodigits */
    47	#define PyLong_SHIFT    30
    48	#define _PyLong_DECIMAL_SHIFT   9 /* max(e such that 10**e fits in a digit) */
    49	#define _PyLong_DECIMAL_BASE    ((digit)1000000000) /* 10 ** DECIMAL_SHIFT */
    50	#elif PYLONG_BITS_IN_DIGIT == 15
    51	typedef unsigned short digit;
    52	typedef short sdigit; /* signed variant of digit */
    53	typedef unsigned long twodigits;
    54	typedef long stwodigits; /* signed variant of twodigits */
    55	#define PyLong_SHIFT    15
    56	#define _PyLong_DECIMAL_SHIFT   4 /* max(e such that 10**e fits in a digit) */
    57	#define _PyLong_DECIMAL_BASE    ((digit)10000) /* 10 ** DECIMAL_SHIFT */
    58	#else
    59	#error "PYLONG_BITS_IN_DIGIT should be 15 or 30"
    60	#endif
    61	#define PyLong_BASE     ((digit)1 << PyLong_SHIFT)
    62	#define PyLong_MASK     ((digit)(PyLong_BASE - 1))
    63	
    64	/* Long integer representation.
    65	   The absolute value of a number is equal to
    66	        SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
    67	   Negative numbers are represented with ob_size < 0;
    68	   zero is represented by ob_size == 0.
    69	   In a normalized number, ob_digit[abs(ob_size)-1] (the most significant
    70	   digit) is never zero.  Also, in all cases, for all valid i,
    71	        0 <= ob_digit[i] <= MASK.
    72	   The allocation function takes care of allocating extra memory
    73	   so that ob_digit[0] ... ob_digit[abs(ob_size)-1] are actually available.
    74	   We always allocate memory for at least one digit, so accessing ob_digit[0]
    75	   is always safe. However, in the case ob_size == 0, the contents of
    76	   ob_digit[0] may be undefined.
    77	
    78	   CAUTION:  Generic code manipulating subtypes of PyVarObject has to
    79	   aware that ints abuse  ob_size's sign bit.
    80	*/
    81	
    82	typedef struct _PyLongValue {
    83	    uintptr_t lv_tag; /* Number of digits, sign and flags */
    84	    digit ob_digit[1];
    85	} _PyLongValue;
    86	
    87	struct _longobject {
    88	    PyObject_HEAD
    89	    _PyLongValue long_value;
    90	};
    91	
    92	PyAPI_FUNC(PyLongObject *) _PyLong_New(Py_ssize_t);
    93	
    94	/* Return a copy of src. */
    95	PyAPI_FUNC(PyObject *) _PyLong_Copy(PyLongObject *src);
    96	
    97	PyAPI_FUNC(PyLongObject *)
    98	_PyLong_FromDigits(int negative, Py_ssize_t digit_count, digit *digits);
    99	
   100	
   101	/* Inline some internals for speed. These should be in pycore_long.h
   102	 * if user code didn't need them inlined. */
   103	
   104	#define _PyLong_SIGN_MASK 3
   105	#define _PyLong_NON_SIZE_BITS 3
   106	
   107	
   108	static inline int
   109	_PyLong_IsCompact(const PyLongObject* op) {
   110	    assert(PyType_HasFeature((op)->ob_base.ob_type, Py_TPFLAGS_LONG_SUBCLASS));
   111	    return op->long_value.lv_tag < (2 << _PyLong_NON_SIZE_BITS);
   112	}
   113	
   114	#define PyUnstable_Long_IsCompact _PyLong_IsCompact
   115	
   116	static inline Py_ssize_t
   117	_PyLong_CompactValue(const PyLongObject *op)
   118	{
   119	    Py_ssize_t sign;
   120	    assert(PyType_HasFeature((op)->ob_base.ob_type, Py_TPFLAGS_LONG_SUBCLASS));
   121	    assert(PyUnstable_Long_IsCompact(op));
   122	    sign = 1 - (op->long_value.lv_tag & _PyLong_SIGN_MASK);
   123	    return sign * (Py_ssize_t)op->long_value.ob_digit[0];
   124	}
   125	
   126	#define PyUnstable_Long_CompactValue _PyLong_CompactValue
   127	
   128	
   129	#ifdef __cplusplus
   130	}
   131	#endif
   132	#endif /* !Py_LONGINTREPR_H */
   133	#endif /* Py_LIMITED_API */