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| extern "C" { | |
| /* 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. | |
| */ | |
| typedef uint32_t digit; | |
| typedef int32_t sdigit; /* signed variant of digit */ | |
| typedef uint64_t twodigits; | |
| typedef int64_t stwodigits; /* signed variant of twodigits */ | |
| typedef unsigned short digit; | |
| typedef short sdigit; /* signed variant of digit */ | |
| typedef unsigned long twodigits; | |
| typedef long stwodigits; /* signed variant of twodigits */ | |
| /* 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); | |
| } | |