floatobject.h 5.6 KB

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  1. /* Float object interface */
  2. /*
  3. PyFloatObject represents a (double precision) floating point number.
  4. */
  5. #ifndef Py_FLOATOBJECT_H
  6. #define Py_FLOATOBJECT_H
  7. #ifdef __cplusplus
  8. extern "C" {
  9. #endif
  10. typedef struct {
  11. PyObject_HEAD
  12. double ob_fval;
  13. } PyFloatObject;
  14. PyAPI_DATA(PyTypeObject) PyFloat_Type;
  15. #define PyFloat_Check(op) PyObject_TypeCheck(op, &PyFloat_Type)
  16. #define PyFloat_CheckExact(op) (Py_TYPE(op) == &PyFloat_Type)
  17. /* The str() precision PyFloat_STR_PRECISION is chosen so that in most cases,
  18. the rounding noise created by various operations is suppressed, while
  19. giving plenty of precision for practical use. */
  20. #define PyFloat_STR_PRECISION 12
  21. #ifdef Py_NAN
  22. #define Py_RETURN_NAN return PyFloat_FromDouble(Py_NAN)
  23. #endif
  24. #define Py_RETURN_INF(sign) do \
  25. if (copysign(1., sign) == 1.) { \
  26. return PyFloat_FromDouble(Py_HUGE_VAL); \
  27. } else { \
  28. return PyFloat_FromDouble(-Py_HUGE_VAL); \
  29. } while(0)
  30. PyAPI_FUNC(double) PyFloat_GetMax(void);
  31. PyAPI_FUNC(double) PyFloat_GetMin(void);
  32. PyAPI_FUNC(PyObject *) PyFloat_GetInfo(void);
  33. /* Return Python float from string PyObject. Second argument ignored on
  34. input, and, if non-NULL, NULL is stored into *junk (this tried to serve a
  35. purpose once but can't be made to work as intended). */
  36. PyAPI_FUNC(PyObject *) PyFloat_FromString(PyObject*, char** junk);
  37. /* Return Python float from C double. */
  38. PyAPI_FUNC(PyObject *) PyFloat_FromDouble(double);
  39. /* Extract C double from Python float. The macro version trades safety for
  40. speed. */
  41. PyAPI_FUNC(double) PyFloat_AsDouble(PyObject *);
  42. #define PyFloat_AS_DOUBLE(op) (((PyFloatObject *)(op))->ob_fval)
  43. /* Write repr(v) into the char buffer argument, followed by null byte. The
  44. buffer must be "big enough"; >= 100 is very safe.
  45. PyFloat_AsReprString(buf, x) strives to print enough digits so that
  46. PyFloat_FromString(buf) then reproduces x exactly. */
  47. PyAPI_FUNC(void) PyFloat_AsReprString(char*, PyFloatObject *v);
  48. /* Write str(v) into the char buffer argument, followed by null byte. The
  49. buffer must be "big enough"; >= 100 is very safe. Note that it's
  50. unusual to be able to get back the float you started with from
  51. PyFloat_AsString's result -- use PyFloat_AsReprString() if you want to
  52. preserve precision across conversions. */
  53. PyAPI_FUNC(void) PyFloat_AsString(char*, PyFloatObject *v);
  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. /* The pack routines write 4 or 8 bytes, starting at p. le is a bool
  76. * argument, true if you want the string in little-endian format (exponent
  77. * last, at p+3 or p+7), false if you want big-endian format (exponent
  78. * first, at p).
  79. * Return value: 0 if all is OK, -1 if error (and an exception is
  80. * set, most likely OverflowError).
  81. * There are two problems on non-IEEE platforms:
  82. * 1): What this does is undefined if x is a NaN or infinity.
  83. * 2): -0.0 and +0.0 produce the same string.
  84. */
  85. PyAPI_FUNC(int) _PyFloat_Pack4(double x, unsigned char *p, int le);
  86. PyAPI_FUNC(int) _PyFloat_Pack8(double x, unsigned char *p, int le);
  87. /* Used to get the important decimal digits of a double */
  88. PyAPI_FUNC(int) _PyFloat_Digits(char *buf, double v, int *signum);
  89. PyAPI_FUNC(void) _PyFloat_DigitsInit(void);
  90. /* The unpack routines read 4 or 8 bytes, starting at p. le is a bool
  91. * argument, true if the string is in little-endian format (exponent
  92. * last, at p+3 or p+7), false if big-endian (exponent first, at p).
  93. * Return value: The unpacked double. On error, this is -1.0 and
  94. * PyErr_Occurred() is true (and an exception is set, most likely
  95. * OverflowError). Note that on a non-IEEE platform this will refuse
  96. * to unpack a string that represents a NaN or infinity.
  97. */
  98. PyAPI_FUNC(double) _PyFloat_Unpack4(const unsigned char *p, int le);
  99. PyAPI_FUNC(double) _PyFloat_Unpack8(const unsigned char *p, int le);
  100. /* free list api */
  101. PyAPI_FUNC(int) PyFloat_ClearFreeList(void);
  102. /* Format the object based on the format_spec, as defined in PEP 3101
  103. (Advanced String Formatting). */
  104. PyAPI_FUNC(PyObject *) _PyFloat_FormatAdvanced(PyObject *obj,
  105. char *format_spec,
  106. Py_ssize_t format_spec_len);
  107. /* Round a C double x to the closest multiple of 10**-ndigits. Returns a
  108. Python float on success, or NULL (with an appropriate exception set) on
  109. failure. Used in builtin_round in bltinmodule.c. */
  110. PyAPI_FUNC(PyObject *) _Py_double_round(double x, int ndigits);
  111. #ifdef __cplusplus
  112. }
  113. #endif
  114. #endif /* !Py_FLOATOBJECT_H */