/src/cpython-install/include/python3.15/cpython/longintrepr.h
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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 | | |
66 | | Long integers are made up of a number of 30- or 15-bit digits, depending on |
67 | | the platform. The number of digits (ndigits) is stored in the high bits of |
68 | | the lv_tag field (lvtag >> _PyLong_NON_SIZE_BITS). |
69 | | |
70 | | The absolute value of a number is equal to |
71 | | SUM(for i=0 through ndigits-1) ob_digit[i] * 2**(PyLong_SHIFT*i) |
72 | | |
73 | | The sign of the value is stored in the lower 2 bits of lv_tag. |
74 | | |
75 | | - 0: Positive |
76 | | - 1: Zero |
77 | | - 2: Negative |
78 | | |
79 | | The third lowest bit of lv_tag is |
80 | | set to 1 for the small ints. |
81 | | |
82 | | In a normalized number, ob_digit[ndigits-1] (the most significant |
83 | | digit) is never zero. Also, in all cases, for all valid i, |
84 | | 0 <= ob_digit[i] <= PyLong_MASK. |
85 | | |
86 | | The allocation function takes care of allocating extra memory |
87 | | so that ob_digit[0] ... ob_digit[ndigits-1] are actually available. |
88 | | We always allocate memory for at least one digit, so accessing ob_digit[0] |
89 | | is always safe. However, in the case ndigits == 0, the contents of |
90 | | ob_digit[0] may be undefined. |
91 | | */ |
92 | | |
93 | | typedef struct _PyLongValue { |
94 | | uintptr_t lv_tag; /* Number of digits, sign and flags */ |
95 | | digit ob_digit[1]; |
96 | | } _PyLongValue; |
97 | | |
98 | | struct _longobject { |
99 | | PyObject_HEAD |
100 | | _PyLongValue long_value; |
101 | | }; |
102 | | |
103 | | Py_DEPRECATED(3.14) PyAPI_FUNC(PyLongObject*) _PyLong_New(Py_ssize_t); |
104 | | |
105 | | // Return a copy of src. |
106 | | PyAPI_FUNC(PyObject*) _PyLong_Copy(PyLongObject *src); |
107 | | |
108 | | Py_DEPRECATED(3.14) PyAPI_FUNC(PyLongObject*) _PyLong_FromDigits( |
109 | | int negative, |
110 | | Py_ssize_t digit_count, |
111 | | digit *digits); |
112 | | |
113 | | |
114 | | /* Inline some internals for speed. These should be in pycore_long.h |
115 | | * if user code didn't need them inlined. */ |
116 | | |
117 | | #define _PyLong_SIGN_MASK 3 |
118 | | #define _PyLong_NON_SIZE_BITS 3 |
119 | | |
120 | | |
121 | | static inline int |
122 | 0 | _PyLong_IsCompact(const PyLongObject* op) { |
123 | 0 | assert(PyType_HasFeature(op->ob_base.ob_type, Py_TPFLAGS_LONG_SUBCLASS)); |
124 | 0 | return op->long_value.lv_tag < (2 << _PyLong_NON_SIZE_BITS); |
125 | 0 | } |
126 | | |
127 | | #define PyUnstable_Long_IsCompact _PyLong_IsCompact |
128 | | |
129 | | static inline Py_ssize_t |
130 | | _PyLong_CompactValue(const PyLongObject *op) |
131 | 0 | { |
132 | 0 | Py_ssize_t sign; |
133 | 0 | assert(PyType_HasFeature(op->ob_base.ob_type, Py_TPFLAGS_LONG_SUBCLASS)); |
134 | 0 | assert(PyUnstable_Long_IsCompact(op)); |
135 | 0 | sign = 1 - (op->long_value.lv_tag & _PyLong_SIGN_MASK); |
136 | 0 | return sign * (Py_ssize_t)op->long_value.ob_digit[0]; |
137 | 0 | } |
138 | | |
139 | | #define PyUnstable_Long_CompactValue _PyLong_CompactValue |
140 | | |
141 | | |
142 | | /* --- Import/Export API -------------------------------------------------- */ |
143 | | |
144 | | typedef struct PyLongLayout { |
145 | | uint8_t bits_per_digit; |
146 | | uint8_t digit_size; |
147 | | int8_t digits_order; |
148 | | int8_t digit_endianness; |
149 | | } PyLongLayout; |
150 | | |
151 | | PyAPI_FUNC(const PyLongLayout*) PyLong_GetNativeLayout(void); |
152 | | |
153 | | typedef struct PyLongExport { |
154 | | int64_t value; |
155 | | uint8_t negative; |
156 | | Py_ssize_t ndigits; |
157 | | const void *digits; |
158 | | // Member used internally, must not be used for other purpose. |
159 | | Py_uintptr_t _reserved; |
160 | | } PyLongExport; |
161 | | |
162 | | PyAPI_FUNC(int) PyLong_Export( |
163 | | PyObject *obj, |
164 | | PyLongExport *export_long); |
165 | | PyAPI_FUNC(void) PyLong_FreeExport( |
166 | | PyLongExport *export_long); |
167 | | |
168 | | |
169 | | /* --- PyLongWriter API --------------------------------------------------- */ |
170 | | |
171 | | typedef struct PyLongWriter PyLongWriter; |
172 | | |
173 | | PyAPI_FUNC(PyLongWriter*) PyLongWriter_Create( |
174 | | int negative, |
175 | | Py_ssize_t ndigits, |
176 | | void **digits); |
177 | | PyAPI_FUNC(PyObject*) PyLongWriter_Finish(PyLongWriter *writer); |
178 | | PyAPI_FUNC(void) PyLongWriter_Discard(PyLongWriter *writer); |
179 | | |
180 | | #ifdef __cplusplus |
181 | | } |
182 | | #endif |
183 | | #endif /* !Py_LONGINTREPR_H */ |
184 | | #endif /* Py_LIMITED_API */ |