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) ((op)->ob_type == &PyFloat_Type)

    23 

    24 /* Return Python float from string PyObject.  Second argument ignored on

    25    input, and, if non-NULL, NULL is stored into *junk (this tried to serve a

    26    purpose once but can't be made to work as intended). */

    27 PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*, char** junk);

    28 

    29 /* Return Python float from C double. */

    30 PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);

    31 

    32 /* Extract C double from Python float.  The macro version trades safety for

    33    speed. */

    34 PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);

    35 #define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)

    36 

    37 /* Write repr(v) into the char buffer argument, followed by null byte.  The

    38    buffer must be "big enough"; >= 100 is very safe.

    39    PyFloat_AsReprString(buf, x) strives to print enough digits so that

    40    PyFloat_FromString(buf) then reproduces x exactly. */

    41 PyAPI_FUNC(void) PyFloat_AsReprString(char*, PyFloatObject *v);

    42 

    43 /* Write str(v) into the char buffer argument, followed by null byte.  The

    44    buffer must be "big enough"; >= 100 is very safe.  Note that it's

    45    unusual to be able to get back the float you started with from

    46    PyFloat_AsString's result -- use PyFloat_AsReprString() if you want to

    47    preserve precision across conversions. */

    48 PyAPI_FUNC(void) PyFloat_AsString(char*, PyFloatObject *v);

    49 

    50 /* _PyFloat_{Pack,Unpack}{4,8}

    51  *

    52  * The struct and pickle (at least) modules need an efficient platform-

    53  * independent way to store floating-point values as byte strings.

    54  * The Pack routines produce a string from a C double, and the Unpack

    55  * routines produce a C double from such a string.  The suffix (4 or 8)

    56  * specifies the number of bytes in the string.

    57  *

    58  * On platforms that appear to use (see _PyFloat_Init()) IEEE-754 formats

    59  * these functions work by copying bits.  On other platforms, the formats the

    60  * 4- byte format is identical to the IEEE-754 single precision format, and

    61  * the 8-byte format to the IEEE-754 double precision format, although the

    62  * packing of INFs and NaNs (if such things exist on the platform) isn't

    63  * handled correctly, and attempting to unpack a string containing an IEEE

    64  * INF or NaN will raise an exception.

    65  *

    66  * On non-IEEE platforms with more precision, or larger dynamic range, than

    67  * 754 supports, not all values can be packed; on non-IEEE platforms with less

    68  * precision, or smaller dynamic range, not all values can be unpacked.  What

    69  * happens in such cases is partly accidental (alas).

    70  */

    71 

    72 /* The pack routines write 4 or 8 bytes, starting at p.  le is a bool

    73  * argument, true if you want the string in little-endian format (exponent

    74  * last, at p+3 or p+7), false if you want big-endian format (exponent

    75  * first, at p).

    76  * Return value:  0 if all is OK, -1 if error (and an exception is

    77  * set, most likely OverflowError).

    78  * There are two problems on non-IEEE platforms:

    79  * 1):  What this does is undefined if x is a NaN or infinity.

    80  * 2):  -0.0 and +0.0 produce the same string.

    81  */

    82 PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);

    83 PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);

    84 

    85 /* The unpack routines read 4 or 8 bytes, starting at p.  le is a bool

    86  * argument, true if the string is in little-endian format (exponent

    87  * last, at p+3 or p+7), false if big-endian (exponent first, at p).

    88  * Return value:  The unpacked double.  On error, this is -1.0 and

    89  * PyErr_Occurred() is true (and an exception is set, most likely

    90  * OverflowError).  Note that on a non-IEEE platform this will refuse

    91  * to unpack a string that represents a NaN or infinity.

    92  */

    93 PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);

    94 PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);

    95 

    96 

    97 #ifdef __cplusplus

    98 }

    99 #endif

   100 #endif /* !Py_FLOATOBJECT_H */