Chris@87: #ifndef Py_LONGINTREPR_H
Chris@87: #define Py_LONGINTREPR_H
Chris@87: #ifdef __cplusplus
Chris@87: extern "C" {
Chris@87: #endif
Chris@87: 
Chris@87: 
Chris@87: /* This is published for the benefit of "friend" marshal.c only. */
Chris@87: 
Chris@87: /* Parameters of the long integer representation.  There are two different
Chris@87:    sets of parameters: one set for 30-bit digits, stored in an unsigned 32-bit
Chris@87:    integer type, and one set for 15-bit digits with each digit stored in an
Chris@87:    unsigned short.  The value of PYLONG_BITS_IN_DIGIT, defined either at
Chris@87:    configure time or in pyport.h, is used to decide which digit size to use.
Chris@87: 
Chris@87:    Type 'digit' should be able to hold 2*PyLong_BASE-1, and type 'twodigits'
Chris@87:    should be an unsigned integer type able to hold all integers up to
Chris@87:    PyLong_BASE*PyLong_BASE-1.  x_sub assumes that 'digit' is an unsigned type,
Chris@87:    and that overflow is handled by taking the result modulo 2**N for some N >
Chris@87:    PyLong_SHIFT.  The majority of the code doesn't care about the precise
Chris@87:    value of PyLong_SHIFT, but there are some notable exceptions:
Chris@87: 
Chris@87:    - long_pow() requires that PyLong_SHIFT be divisible by 5
Chris@87: 
Chris@87:    - PyLong_{As,From}ByteArray require that PyLong_SHIFT be at least 8
Chris@87: 
Chris@87:    - long_hash() requires that PyLong_SHIFT is *strictly* less than the number
Chris@87:      of bits in an unsigned long, as do the PyLong <-> long (or unsigned long)
Chris@87:      conversion functions
Chris@87: 
Chris@87:    - the long <-> size_t/Py_ssize_t conversion functions expect that
Chris@87:      PyLong_SHIFT is strictly less than the number of bits in a size_t
Chris@87: 
Chris@87:    - the marshal code currently expects that PyLong_SHIFT is a multiple of 15
Chris@87: 
Chris@87:   The values 15 and 30 should fit all of the above requirements, on any
Chris@87:   platform.
Chris@87: */
Chris@87: 
Chris@87: #if PYLONG_BITS_IN_DIGIT == 30
Chris@87: #if !(defined HAVE_UINT64_T && defined HAVE_UINT32_T &&          \
Chris@87:       defined HAVE_INT64_T && defined HAVE_INT32_T)
Chris@87: #error "30-bit long digits requested, but the necessary types are not available on this platform"
Chris@87: #endif
Chris@87: typedef PY_UINT32_T digit;
Chris@87: typedef PY_INT32_T sdigit; /* signed variant of digit */
Chris@87: typedef PY_UINT64_T twodigits;
Chris@87: typedef PY_INT64_T stwodigits; /* signed variant of twodigits */
Chris@87: #define PyLong_SHIFT	30
Chris@87: #define _PyLong_DECIMAL_SHIFT	9 /* max(e such that 10**e fits in a digit) */
Chris@87: #define _PyLong_DECIMAL_BASE	((digit)1000000000) /* 10 ** DECIMAL_SHIFT */
Chris@87: #elif PYLONG_BITS_IN_DIGIT == 15
Chris@87: typedef unsigned short digit;
Chris@87: typedef short sdigit; /* signed variant of digit */
Chris@87: typedef unsigned long twodigits;
Chris@87: typedef long stwodigits; /* signed variant of twodigits */
Chris@87: #define PyLong_SHIFT	15
Chris@87: #define _PyLong_DECIMAL_SHIFT	4 /* max(e such that 10**e fits in a digit) */
Chris@87: #define _PyLong_DECIMAL_BASE	((digit)10000) /* 10 ** DECIMAL_SHIFT */
Chris@87: #else
Chris@87: #error "PYLONG_BITS_IN_DIGIT should be 15 or 30"
Chris@87: #endif
Chris@87: #define PyLong_BASE	((digit)1 << PyLong_SHIFT)
Chris@87: #define PyLong_MASK	((digit)(PyLong_BASE - 1))
Chris@87: 
Chris@87: /* b/w compatibility with Python 2.5 */
Chris@87: #define SHIFT	PyLong_SHIFT
Chris@87: #define BASE	PyLong_BASE
Chris@87: #define MASK	PyLong_MASK
Chris@87: 
Chris@87: #if PyLong_SHIFT % 5 != 0
Chris@87: #error "longobject.c requires that PyLong_SHIFT be divisible by 5"
Chris@87: #endif
Chris@87: 
Chris@87: /* Long integer representation.
Chris@87:    The absolute value of a number is equal to
Chris@87:    	SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
Chris@87:    Negative numbers are represented with ob_size < 0;
Chris@87:    zero is represented by ob_size == 0.
Chris@87:    In a normalized number, ob_digit[abs(ob_size)-1] (the most significant
Chris@87:    digit) is never zero.  Also, in all cases, for all valid i,
Chris@87:    	0 <= ob_digit[i] <= MASK.
Chris@87:    The allocation function takes care of allocating extra memory
Chris@87:    so that ob_digit[0] ... ob_digit[abs(ob_size)-1] are actually available.
Chris@87: 
Chris@87:    CAUTION:  Generic code manipulating subtypes of PyVarObject has to
Chris@87:    aware that longs abuse  ob_size's sign bit.
Chris@87: */
Chris@87: 
Chris@87: struct _longobject {
Chris@87: 	PyObject_VAR_HEAD
Chris@87: 	digit ob_digit[1];
Chris@87: };
Chris@87: 
Chris@87: PyAPI_FUNC(PyLongObject *) _PyLong_New(Py_ssize_t);
Chris@87: 
Chris@87: /* Return a copy of src. */
Chris@87: PyAPI_FUNC(PyObject *) _PyLong_Copy(PyLongObject *src);
Chris@87: 
Chris@87: #ifdef __cplusplus
Chris@87: }
Chris@87: #endif
Chris@87: #endif /* !Py_LONGINTREPR_H */