I got the relative magnitudes of the timeout increases reversed, so
[python.git] / Include / floatobject.h
blob6c11036190aa44fbcd0dbdc340283d4d0d49a828
2 /* Float object interface */
4 /*
5 PyFloatObject represents a (double precision) floating point number.
6 */
8 #ifndef Py_FLOATOBJECT_H
9 #define Py_FLOATOBJECT_H
10 #ifdef __cplusplus
11 extern "C" {
12 #endif
14 typedef struct {
15 PyObject_HEAD
16 double ob_fval;
17 } PyFloatObject;
19 PyAPI_DATA(PyTypeObject) PyFloat_Type;
21 #define PyFloat_Check(op) PyObject_TypeCheck(op, &PyFloat_Type)
22 #define PyFloat_CheckExact(op) (Py_TYPE(op) == &PyFloat_Type)
24 /* The str() precision PyFloat_STR_PRECISION is chosen so that in most cases,
25 the rounding noise created by various operations is suppressed, while
26 giving plenty of precision for practical use. */
28 #define PyFloat_STR_PRECISION 12
30 #ifdef Py_NAN
31 #define Py_RETURN_NAN return PyFloat_FromDouble(Py_NAN)
32 #endif
34 #define Py_RETURN_INF(sign) do \
35 if (copysign(1., sign) == 1.) { \
36 return PyFloat_FromDouble(Py_HUGE_VAL); \
37 } else { \
38 return PyFloat_FromDouble(-Py_HUGE_VAL); \
39 } while(0)
41 PyAPI_FUNC(double) PyFloat_GetMax(void);
42 PyAPI_FUNC(double) PyFloat_GetMin(void);
43 PyAPI_FUNC(PyObject *) PyFloat_GetInfo(void);
45 /* Return Python float from string PyObject. Second argument ignored on
46 input, and, if non-NULL, NULL is stored into *junk (this tried to serve a
47 purpose once but can't be made to work as intended). */
48 PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*, char** junk);
50 /* Return Python float from C double. */
51 PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);
53 /* Extract C double from Python float. The macro version trades safety for
54 speed. */
55 PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);
56 #define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)
58 /* Write repr(v) into the char buffer argument, followed by null byte. The
59 buffer must be "big enough"; >= 100 is very safe.
60 PyFloat_AsReprString(buf, x) strives to print enough digits so that
61 PyFloat_FromString(buf) then reproduces x exactly. */
62 PyAPI_FUNC(void) PyFloat_AsReprString(char*, PyFloatObject *v);
64 /* Write str(v) into the char buffer argument, followed by null byte. The
65 buffer must be "big enough"; >= 100 is very safe. Note that it's
66 unusual to be able to get back the float you started with from
67 PyFloat_AsString's result -- use PyFloat_AsReprString() if you want to
68 preserve precision across conversions. */
69 PyAPI_FUNC(void) PyFloat_AsString(char*, PyFloatObject *v);
71 /* _PyFloat_{Pack,Unpack}{4,8}
73 * The struct and pickle (at least) modules need an efficient platform-
74 * independent way to store floating-point values as byte strings.
75 * The Pack routines produce a string from a C double, and the Unpack
76 * routines produce a C double from such a string. The suffix (4 or 8)
77 * specifies the number of bytes in the string.
79 * On platforms that appear to use (see _PyFloat_Init()) IEEE-754 formats
80 * these functions work by copying bits. On other platforms, the formats the
81 * 4- byte format is identical to the IEEE-754 single precision format, and
82 * the 8-byte format to the IEEE-754 double precision format, although the
83 * packing of INFs and NaNs (if such things exist on the platform) isn't
84 * handled correctly, and attempting to unpack a string containing an IEEE
85 * INF or NaN will raise an exception.
87 * On non-IEEE platforms with more precision, or larger dynamic range, than
88 * 754 supports, not all values can be packed; on non-IEEE platforms with less
89 * precision, or smaller dynamic range, not all values can be unpacked. What
90 * happens in such cases is partly accidental (alas).
93 /* The pack routines write 4 or 8 bytes, starting at p. le is a bool
94 * argument, true if you want the string in little-endian format (exponent
95 * last, at p+3 or p+7), false if you want big-endian format (exponent
96 * first, at p).
97 * Return value: 0 if all is OK, -1 if error (and an exception is
98 * set, most likely OverflowError).
99 * There are two problems on non-IEEE platforms:
100 * 1): What this does is undefined if x is a NaN or infinity.
101 * 2): -0.0 and +0.0 produce the same string.
103 PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
104 PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
106 /* Used to get the important decimal digits of a double */
107 PyAPI_FUNC(int) _PyFloat_Digits(char *buf, double v, int *signum);
108 PyAPI_FUNC(void) _PyFloat_DigitsInit(void);
110 /* The unpack routines read 4 or 8 bytes, starting at p. le is a bool
111 * argument, true if the string is in little-endian format (exponent
112 * last, at p+3 or p+7), false if big-endian (exponent first, at p).
113 * Return value: The unpacked double. On error, this is -1.0 and
114 * PyErr_Occurred() is true (and an exception is set, most likely
115 * OverflowError). Note that on a non-IEEE platform this will refuse
116 * to unpack a string that represents a NaN or infinity.
118 PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
119 PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
121 /* free list api */
122 PyAPI_FUNC(int) PyFloat_ClearFreeList(void);
124 /* Format the object based on the format_spec, as defined in PEP 3101
125 (Advanced String Formatting). */
126 PyAPI_FUNC(PyObject *) _PyFloat_FormatAdvanced(PyObject *obj,
127 char *format_spec,
128 Py_ssize_t format_spec_len);
130 #ifdef __cplusplus
132 #endif
133 #endif /* !Py_FLOATOBJECT_H */