1 2 /* Float object interface */ 3 4 /* 5 PyFloatObject represents a (double precision) floating point number. 6 */ 7 8 #ifndef Py_FLOATOBJECT_H 9 #define Py_FLOATOBJECT_H 10 #ifdef __cplusplus 11 extern "C" { 12 #endif 13 14 typedef struct { 15 PyObject_HEAD 16 double ob_fval; 17 } PyFloatObject; 18 19 PyAPI_DATA(PyTypeObject) PyFloat_Type; 20 21 #define PyFloat_Check(op) PyObject_TypeCheck(op, &PyFloat_Type) 22 #define PyFloat_CheckExact(op) (Py_TYPE(op) == &PyFloat_Type) 23 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. */ 27 28 #define PyFloat_STR_PRECISION 12 29 30 #ifdef Py_NAN 31 #define Py_RETURN_NAN return PyFloat_FromDouble(Py_NAN) 32 #endif 33 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) 40 41 PyAPI_FUNC(double) PyFloat_GetMax(void); 42 PyAPI_FUNC(double) PyFloat_GetMin(void); 43 PyAPI_FUNC(PyObject *) PyFloat_GetInfo(void); 44 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); 49 50 /* Return Python float from C double. */ 51 PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double); 52 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) 57 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); 63 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); 70 71 /* _PyFloat_{Pack,Unpack}{4,8} 72 * 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. 78 * 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. 86 * 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). 91 */ 92 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. 102 */ 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); 105 106 /* 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); 109 110 /* 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. 117 */ 118 PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le); 119 PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le); 120 121 /* free list api */ 122 PyAPI_FUNC(int) PyFloat_ClearFreeList(void); 123 124 /* 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); 129 130 /* Round a C double x to the closest multiple of 10**-ndigits. Returns a 131 Python float on success, or NULL (with an appropriate exception set) on 132 failure. Used in builtin_round in bltinmodule.c. */ 133 PyAPI_FUNC(PyObject *) _Py_double_round(double x, int ndigits); 134 135 136 137 #ifdef __cplusplus 138 } 139 #endif 140 #endif /* !Py_FLOATOBJECT_H */ 141
