LXR qemu/include/qapi/qmp/qnum.h

   1/*
   2 * QNum Module
   3 *
   4 * Copyright (C) 2009 Red Hat Inc.
   5 *
   6 * Authors:
   7 *  Luiz Capitulino <lcapitulino@redhat.com>
   8 *  Anthony Liguori <aliguori@us.ibm.com>
   9 *  Marc-André Lureau <marcandre.lureau@redhat.com>
  10 *
  11 * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
  12 * See the COPYING.LIB file in the top-level directory.
  13 */
  14
  15#ifndef QNUM_H
  16#define QNUM_H
  17
  18#include "qapi/qmp/qobject.h"
  19
  20typedef enum {
  21    QNUM_I64,
  22    QNUM_U64,
  23    QNUM_DOUBLE
  24} QNumKind;
  25
  26/*
  27 * QNum encapsulates how our dialect of JSON fills in the blanks left
  28 * by the JSON specification (RFC 8259) regarding numbers.
  29 *
  30 * Conceptually, we treat number as an abstract type with three
  31 * concrete subtypes: floating-point, signed integer, unsigned
  32 * integer.  QNum implements this as a discriminated union of double,
  33 * int64_t, uint64_t.
  34 *
  35 * The JSON parser picks the subtype as follows.  If the number has a
  36 * decimal point or an exponent, it is floating-point.  Else if it
  37 * fits into int64_t, it's signed integer.  Else if it fits into
  38 * uint64_t, it's unsigned integer.  Else it's floating-point.
  39 *
  40 * Any number can serve as double: qnum_get_double() converts under
  41 * the hood.
  42 *
  43 * An integer can serve as signed / unsigned integer as long as it is
  44 * in range: qnum_get_try_int() / qnum_get_try_uint() check range and
  45 * convert under the hood.
  46 */
  47struct QNum {
  48    struct QObjectBase_ base;
  49    QNumKind kind;
  50    union {
  51        int64_t i64;
  52        uint64_t u64;
  53        double dbl;
  54    } u;
  55};
  56
  57void qnum_unref(QNum *q);
  58
  59G_DEFINE_AUTOPTR_CLEANUP_FUNC(QNum, qnum_unref)
  60
  61QNum *qnum_from_int(int64_t value);
  62QNum *qnum_from_uint(uint64_t value);
  63QNum *qnum_from_double(double value);
  64
  65bool qnum_get_try_int(const QNum *qn, int64_t *val);
  66int64_t qnum_get_int(const QNum *qn);
  67
  68bool qnum_get_try_uint(const QNum *qn, uint64_t *val);
  69uint64_t qnum_get_uint(const QNum *qn);
  70
  71double qnum_get_double(QNum *qn);
  72
  73char *qnum_to_string(QNum *qn);
  74
  75#endif /* QNUM_H */
  76