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 /* 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. */
  46 PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*);
  47
  48 /* Return Python float from C double. */
  49 PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);
  50
  51 /* Extract C double from Python float.  The macro version trades safety for
  52    speed. */
  53 PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);
  54 #define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)
  55
  56 /* _PyFloat_{Pack,Unpack}{4,8}
  57  *
  58  * The struct and pickle (at least) modules need an efficient platform-
  59  * independent way to store floating-point values as byte strings.
  60  * The Pack routines produce a string from a C double, and the Unpack
  61  * routines produce a C double from such a string.  The suffix (4 or 8)
  62  * specifies the number of bytes in the string.
  63  *
  64  * On platforms that appear to use (see _PyFloat_Init()) IEEE-754 formats
  65  * these functions work by copying bits.  On other platforms, the formats the
  66  * 4- byte format is identical to the IEEE-754 single precision format, and
  67  * the 8-byte format to the IEEE-754 double precision format, although the
  68  * packing of INFs and NaNs (if such things exist on the platform) isn't
  69  * handled correctly, and attempting to unpack a string containing an IEEE
  70  * INF or NaN will raise an exception.
  71  *
  72  * On non-IEEE platforms with more precision, or larger dynamic range, than
  73  * 754 supports, not all values can be packed; on non-IEEE platforms with less
  74  * precision, or smaller dynamic range, not all values can be unpacked.  What
  75  * happens in such cases is partly accidental (alas).
  76  */
  77
  78 /* The pack routines write 4 or 8 bytes, starting at p.  le is a bool
  79  * argument, true if you want the string in little-endian format (exponent
  80  * last, at p+3 or p+7), false if you want big-endian format (exponent
  81  * first, at p).
  82  * Return value:  0 if all is OK, -1 if error (and an exception is
  83  * set, most likely OverflowError).
  84  * There are two problems on non-IEEE platforms:
  85  * 1):  What this does is undefined if x is a NaN or infinity.
  86  * 2):  -0.0 and +0.0 produce the same string.
  87  */
  88 PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
  89 PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
  90
  91 /* Needed for the old way for marshal to store a floating point number.
  92    Returns the string length copied into p, -1 on error.
  93  */
  94 PyAPI_FUNC(int) _PyFloat_Repr(double x, char *p, size_t len);
  95
  96 /* Used to get the important decimal digits of a double */
  97 PyAPI_FUNC(int) _PyFloat_Digits(char *buf, double v, int *signum);
  98 PyAPI_FUNC(void) _PyFloat_DigitsInit(void);
  99
 100 /* The unpack routines read 4 or 8 bytes, starting at p.  le is a bool
 101  * argument, true if the string is in little-endian format (exponent
 102  * last, at p+3 or p+7), false if big-endian (exponent first, at p).
 103  * Return value:  The unpacked double.  On error, this is -1.0 and
 104  * PyErr_Occurred() is true (and an exception is set, most likely
 105  * OverflowError).  Note that on a non-IEEE platform this will refuse
 106  * to unpack a string that represents a NaN or infinity.
 107  */
 108 PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
 109 PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
 110
 111 /* free list api */
 112 PyAPI_FUNC(int) PyFloat_ClearFreeList(void);
 113
 114 /* Format the object based on the format_spec, as defined in PEP 3101
 115    (Advanced String Formatting). */
 116 PyAPI_FUNC(PyObject *) _PyFloat_FormatAdvanced(PyObject *obj,
 117                                                Py_UNICODE *format_spec,
 118                                                Py_ssize_t format_spec_len);
 119
 120 #ifdef __cplusplus
 121 }
 122 #endif
 123 #endif /* !Py_FLOATOBJECT_H */