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90 lines
3.4 KiB
C
90 lines
3.4 KiB
C
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/* Float object interface */
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/*
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PyFloatObject represents a (double precision) floating point number.
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*/
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#ifndef Py_FLOATOBJECT_H
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#define Py_FLOATOBJECT_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef struct {
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PyObject_HEAD
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double ob_fval;
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} PyFloatObject;
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PyAPI_DATA(PyTypeObject) PyFloat_Type;
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#define PyFloat_Check(op) PyObject_TypeCheck(op, &PyFloat_Type)
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#define PyFloat_CheckExact(op) ((op)->ob_type == &PyFloat_Type)
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/* Return Python float from string PyObject. */
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PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*);
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/* Return Python float from C double. */
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PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);
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/* Extract C double from Python float. The macro version trades safety for
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speed. */
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PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);
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#define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)
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/* _PyFloat_{Pack,Unpack}{4,8}
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*
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* The struct and pickle (at least) modules need an efficient platform-
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* independent way to store floating-point values as byte strings.
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* The Pack routines produce a string from a C double, and the Unpack
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* routines produce a C double from such a string. The suffix (4 or 8)
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* specifies the number of bytes in the string.
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*
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* On platforms that appear to use (see _PyFloat_Init()) IEEE-754 formats
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* these functions work by copying bits. On other platforms, the formats the
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* 4- byte format is identical to the IEEE-754 single precision format, and
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* the 8-byte format to the IEEE-754 double precision format, although the
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* packing of INFs and NaNs (if such things exist on the platform) isn't
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* handled correctly, and attempting to unpack a string containing an IEEE
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* INF or NaN will raise an exception.
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*
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* On non-IEEE platforms with more precision, or larger dynamic range, than
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* 754 supports, not all values can be packed; on non-IEEE platforms with less
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* precision, or smaller dynamic range, not all values can be unpacked. What
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* happens in such cases is partly accidental (alas).
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*/
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/* The pack routines write 4 or 8 bytes, starting at p. le is a bool
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* argument, true if you want the string in little-endian format (exponent
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* last, at p+3 or p+7), false if you want big-endian format (exponent
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* first, at p).
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* Return value: 0 if all is OK, -1 if error (and an exception is
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* set, most likely OverflowError).
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* There are two problems on non-IEEE platforms:
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* 1): What this does is undefined if x is a NaN or infinity.
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* 2): -0.0 and +0.0 produce the same string.
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*/
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PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
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PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
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/* Needed for the old way for marshal to store a floating point number.
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Returns the string length copied into p, -1 on error.
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*/
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PyAPI_FUNC(int) _PyFloat_Repr(double x, char *p, size_t len);
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/* The unpack routines read 4 or 8 bytes, starting at p. le is a bool
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* argument, true if the string is in little-endian format (exponent
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* last, at p+3 or p+7), false if big-endian (exponent first, at p).
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* Return value: The unpacked double. On error, this is -1.0 and
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* PyErr_Occurred() is true (and an exception is set, most likely
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* OverflowError). Note that on a non-IEEE platform this will refuse
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* to unpack a string that represents a NaN or infinity.
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*/
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PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
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PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
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#ifdef __cplusplus
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}
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#endif
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#endif /* !Py_FLOATOBJECT_H */
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