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