diff options
Diffstat (limited to 'Include/internal/pycore_long.h')
| -rw-r--r-- | Include/internal/pycore_long.h | 164 |
1 files changed, 146 insertions, 18 deletions
diff --git a/Include/internal/pycore_long.h b/Include/internal/pycore_long.h index 8c1d017..137a046 100644 --- a/Include/internal/pycore_long.h +++ b/Include/internal/pycore_long.h @@ -82,8 +82,6 @@ PyObject *_PyLong_Add(PyLongObject *left, PyLongObject *right); PyObject *_PyLong_Multiply(PyLongObject *left, PyLongObject *right); PyObject *_PyLong_Subtract(PyLongObject *left, PyLongObject *right); -int _PyLong_AssignValue(PyObject **target, Py_ssize_t value); - /* Used by Python/mystrtoul.c, _PyBytes_FromHex(), _PyBytes_DecodeEscape(), etc. */ PyAPI_DATA(unsigned char) _PyLong_DigitValue[256]; @@ -110,25 +108,155 @@ PyAPI_FUNC(char*) _PyLong_FormatBytesWriter( int base, int alternate); -/* Return 1 if the argument is positive single digit int */ +/* Long value tag bits: + * 0-1: Sign bits value = (1-sign), ie. negative=2, positive=0, zero=1. + * 2: Reserved for immortality bit + * 3+ Unsigned digit count + */ +#define SIGN_MASK 3 +#define SIGN_ZERO 1 +#define SIGN_NEGATIVE 2 +#define NON_SIZE_BITS 3 + +/* All *compact" values are guaranteed to fit into + * a Py_ssize_t with at least one bit to spare. + * In other words, for 64 bit machines, compact + * will be signed 63 (or fewer) bit values + */ + +/* Return 1 if the argument is compact int */ +static inline int +_PyLong_IsNonNegativeCompact(const PyLongObject* op) { + assert(PyLong_Check(op)); + return op->long_value.lv_tag <= (1 << NON_SIZE_BITS); +} + +static inline int +_PyLong_IsCompact(const PyLongObject* op) { + assert(PyLong_Check(op)); + return op->long_value.lv_tag < (2 << NON_SIZE_BITS); +} + static inline int -_PyLong_IsPositiveSingleDigit(PyObject* sub) { - /* For a positive single digit int, the value of Py_SIZE(sub) is 0 or 1. - - We perform a fast check using a single comparison by casting from int - to uint which casts negative numbers to large positive numbers. - For details see Section 14.2 "Bounds Checking" in the Agner Fog - optimization manual found at: - https://www.agner.org/optimize/optimizing_cpp.pdf - - The function is not affected by -fwrapv, -fno-wrapv and -ftrapv - compiler options of GCC and clang - */ - assert(PyLong_CheckExact(sub)); - Py_ssize_t signed_size = Py_SIZE(sub); - return ((size_t)signed_size) <= 1; +_PyLong_BothAreCompact(const PyLongObject* a, const PyLongObject* b) { + assert(PyLong_Check(a)); + assert(PyLong_Check(b)); + return (a->long_value.lv_tag | b->long_value.lv_tag) < (2 << NON_SIZE_BITS); +} + +/* Returns a *compact* value, iff `_PyLong_IsCompact` is true for `op`. + * + * "Compact" values have at least one bit to spare, + * so that addition and subtraction can be performed on the values + * without risk of overflow. + */ +static inline Py_ssize_t +_PyLong_CompactValue(const PyLongObject *op) +{ + assert(PyLong_Check(op)); + assert(_PyLong_IsCompact(op)); + Py_ssize_t sign = 1 - (op->long_value.lv_tag & SIGN_MASK); + return sign * (Py_ssize_t)op->long_value.ob_digit[0]; +} + +static inline bool +_PyLong_IsZero(const PyLongObject *op) +{ + return (op->long_value.lv_tag & SIGN_MASK) == SIGN_ZERO; +} + +static inline bool +_PyLong_IsNegative(const PyLongObject *op) +{ + return (op->long_value.lv_tag & SIGN_MASK) == SIGN_NEGATIVE; +} + +static inline bool +_PyLong_IsPositive(const PyLongObject *op) +{ + return (op->long_value.lv_tag & SIGN_MASK) == 0; +} + +static inline Py_ssize_t +_PyLong_DigitCount(const PyLongObject *op) +{ + assert(PyLong_Check(op)); + return op->long_value.lv_tag >> NON_SIZE_BITS; } +/* Equivalent to _PyLong_DigitCount(op) * _PyLong_NonCompactSign(op) */ +static inline Py_ssize_t +_PyLong_SignedDigitCount(const PyLongObject *op) +{ + assert(PyLong_Check(op)); + Py_ssize_t sign = 1 - (op->long_value.lv_tag & SIGN_MASK); + return sign * (Py_ssize_t)(op->long_value.lv_tag >> NON_SIZE_BITS); +} + +static inline int +_PyLong_CompactSign(const PyLongObject *op) +{ + assert(PyLong_Check(op)); + assert(_PyLong_IsCompact(op)); + return 1 - (op->long_value.lv_tag & SIGN_MASK); +} + +static inline int +_PyLong_NonCompactSign(const PyLongObject *op) +{ + assert(PyLong_Check(op)); + assert(!_PyLong_IsCompact(op)); + return 1 - (op->long_value.lv_tag & SIGN_MASK); +} + +/* Do a and b have the same sign? */ +static inline int +_PyLong_SameSign(const PyLongObject *a, const PyLongObject *b) +{ + return (a->long_value.lv_tag & SIGN_MASK) == (b->long_value.lv_tag & SIGN_MASK); +} + +#define TAG_FROM_SIGN_AND_SIZE(sign, size) ((1 - (sign)) | ((size) << NON_SIZE_BITS)) + +static inline void +_PyLong_SetSignAndDigitCount(PyLongObject *op, int sign, Py_ssize_t size) +{ + assert(size >= 0); + assert(-1 <= sign && sign <= 1); + assert(sign != 0 || size == 0); + op->long_value.lv_tag = TAG_FROM_SIGN_AND_SIZE(sign, (size_t)size); +} + +static inline void +_PyLong_SetDigitCount(PyLongObject *op, Py_ssize_t size) +{ + assert(size >= 0); + op->long_value.lv_tag = (((size_t)size) << NON_SIZE_BITS) | (op->long_value.lv_tag & SIGN_MASK); +} + +#define NON_SIZE_MASK ~((1 << NON_SIZE_BITS) - 1) + +static inline void +_PyLong_FlipSign(PyLongObject *op) { + unsigned int flipped_sign = 2 - (op->long_value.lv_tag & SIGN_MASK); + op->long_value.lv_tag &= NON_SIZE_MASK; + op->long_value.lv_tag |= flipped_sign; +} + +#define _PyLong_DIGIT_INIT(val) \ + { \ + .ob_base = _PyObject_IMMORTAL_INIT(&PyLong_Type), \ + .long_value = { \ + .lv_tag = TAG_FROM_SIGN_AND_SIZE( \ + (val) == 0 ? 0 : ((val) < 0 ? -1 : 1), \ + (val) == 0 ? 0 : 1), \ + { ((val) >= 0 ? (val) : -(val)) }, \ + } \ + } + +#define _PyLong_FALSE_TAG TAG_FROM_SIGN_AND_SIZE(0, 0) +#define _PyLong_TRUE_TAG TAG_FROM_SIGN_AND_SIZE(1, 1) + #ifdef __cplusplus } #endif |