Andrew Hsieh | 83760d2 | 2013-06-18 12:24:28 -0700 | [diff] [blame^] | 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 */ |