Include/floatobject.h

   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 #ifdef Py_NAN
  25 #define Py_RETURN_NAN return PyFloat_FromDouble(Py_NAN)
  26 #endif
  27
  28 #define Py_RETURN_INF(sign) do                                  \
  29         if (copysign(1., sign) == 1.) {                         \
  30                 return PyFloat_FromDouble(Py_HUGE_VAL); \
  31         } else {                                                \
  32                 return PyFloat_FromDouble(-Py_HUGE_VAL);        \
  33         } while(0)
  34
  35 PyAPI_FUNC(double) PyFloat_GetMax(void);
  36 PyAPI_FUNC(double) PyFloat_GetMin(void);
  37 PyAPI_FUNC(PyObject *) PyFloat_GetInfo(void);
  38
  39 /* Return Python float from string PyObject.  Second argument ignored on
  40    input, and, if non-NULL, NULL is stored into *junk (this tried to serve a
  41    purpose once but can't be made to work as intended). */
  42 PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*, char** junk);
  43
  44 /* Return Python float from C double. */
  45 PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);
  46
  47 /* Extract C double from Python float.  The macro version trades safety for
  48    speed. */
  49 PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);
  50 #define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)
  51
  52 /* Write repr(v) into the char buffer argument, followed by null byte.  The
  53    buffer must be "big enough"; >= 100 is very safe.
  54    PyFloat_AsReprString(buf, x) strives to print enough digits so that
  55    PyFloat_FromString(buf) then reproduces x exactly. */
  56 PyAPI_FUNC(void) PyFloat_AsReprString(char*, PyFloatObject *v);
  57
  58 /* Write str(v) into the char buffer argument, followed by null byte.  The
  59    buffer must be "big enough"; >= 100 is very safe.  Note that it's
  60    unusual to be able to get back the float you started with from
  61    PyFloat_AsString's result -- use PyFloat_AsReprString() if you want to
  62    preserve precision across conversions. */
  63 PyAPI_FUNC(void) PyFloat_AsString(char*, PyFloatObject *v);
  64
  65 /* _PyFloat_{Pack,Unpack}{4,8}
  66  *
  67  * The struct and pickle (at least) modules need an efficient platform-
  68  * independent way to store floating-point values as byte strings.
  69  * The Pack routines produce a string from a C double, and the Unpack
  70  * routines produce a C double from such a string.  The suffix (4 or 8)
  71  * specifies the number of bytes in the string.
  72  *
  73  * On platforms that appear to use (see _PyFloat_Init()) IEEE-754 formats
  74  * these functions work by copying bits.  On other platforms, the formats the
  75  * 4- byte format is identical to the IEEE-754 single precision format, and
  76  * the 8-byte format to the IEEE-754 double precision format, although the
  77  * packing of INFs and NaNs (if such things exist on the platform) isn't
  78  * handled correctly, and attempting to unpack a string containing an IEEE
  79  * INF or NaN will raise an exception.
  80  *
  81  * On non-IEEE platforms with more precision, or larger dynamic range, than
  82  * 754 supports, not all values can be packed; on non-IEEE platforms with less
  83  * precision, or smaller dynamic range, not all values can be unpacked.  What
  84  * happens in such cases is partly accidental (alas).
  85  */
  86
  87 /* The pack routines write 4 or 8 bytes, starting at p.  le is a bool
  88  * argument, true if you want the string in little-endian format (exponent
  89  * last, at p+3 or p+7), false if you want big-endian format (exponent
  90  * first, at p).
  91  * Return value:  0 if all is OK, -1 if error (and an exception is
  92  * set, most likely OverflowError).
  93  * There are two problems on non-IEEE platforms:
  94  * 1):  What this does is undefined if x is a NaN or infinity.
  95  * 2):  -0.0 and +0.0 produce the same string.
  96  */
  97 PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
  98 PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
  99
 100 /* Used to get the important decimal digits of a double */
 101 PyAPI_FUNC(int) _PyFloat_Digits(char *buf, double v, int *signum);
 102 PyAPI_FUNC(void) _PyFloat_DigitsInit(void);
 103
 104 /* The unpack routines read 4 or 8 bytes, starting at p.  le is a bool
 105  * argument, true if the string is in little-endian format (exponent
 106  * last, at p+3 or p+7), false if big-endian (exponent first, at p).
 107  * Return value:  The unpacked double.  On error, this is -1.0 and
 108  * PyErr_Occurred() is true (and an exception is set, most likely
 109  * OverflowError).  Note that on a non-IEEE platform this will refuse
 110  * to unpack a string that represents a NaN or infinity.
 111  */
 112 PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
 113 PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
 114
 115 /* free list api */
 116 PyAPI_FUNC(int) PyFloat_ClearFreeList(void);
 117
 118 /* Format the object based on the format_spec, as defined in PEP 3101
 119    (Advanced String Formatting). */
 120 PyAPI_FUNC(PyObject *) _PyFloat_FormatAdvanced(PyObject *obj,
 121                                                char *format_spec,
 122                                                Py_ssize_t format_spec_len);
 123
 124 #ifdef __cplusplus
 125 }
 126 #endif
 127 #endif /* !Py_FLOATOBJECT_H */