Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 71 insertions, 0 deletions

diff --git a/include/qapi/qmp/qnum.h b/include/qapi/qmp/qnum.h
new file mode 100644
index 000000000..7f84e20bf
--- /dev/null
+++ b/include/qapi/qmp/qnum.h
@@ -0,0 +1,71 @@
+/*
+ * QNum Module
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *  Anthony Liguori <aliguori@us.ibm.com>
+ *  Marc-André Lureau <marcandre.lureau@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ */
+
+#ifndef QNUM_H
+#define QNUM_H
+
+#include "qapi/qmp/qobject.h"
+
+typedef enum {
+    QNUM_I64,
+    QNUM_U64,
+    QNUM_DOUBLE
+} QNumKind;
+
+/*
+ * QNum encapsulates how our dialect of JSON fills in the blanks left
+ * by the JSON specification (RFC 8259) regarding numbers.
+ *
+ * Conceptually, we treat number as an abstract type with three
+ * concrete subtypes: floating-point, signed integer, unsigned
+ * integer.  QNum implements this as a discriminated union of double,
+ * int64_t, uint64_t.
+ *
+ * The JSON parser picks the subtype as follows.  If the number has a
+ * decimal point or an exponent, it is floating-point.  Else if it
+ * fits into int64_t, it's signed integer.  Else if it fits into
+ * uint64_t, it's unsigned integer.  Else it's floating-point.
+ *
+ * Any number can serve as double: qnum_get_double() converts under
+ * the hood.
+ *
+ * An integer can serve as signed / unsigned integer as long as it is
+ * in range: qnum_get_try_int() / qnum_get_try_uint() check range and
+ * convert under the hood.
+ */
+struct QNum {
+    struct QObjectBase_ base;
+    QNumKind kind;
+    union {
+        int64_t i64;
+        uint64_t u64;
+        double dbl;
+    } u;
+};
+
+QNum *qnum_from_int(int64_t value);
+QNum *qnum_from_uint(uint64_t value);
+QNum *qnum_from_double(double value);
+
+bool qnum_get_try_int(const QNum *qn, int64_t *val);
+int64_t qnum_get_int(const QNum *qn);
+
+bool qnum_get_try_uint(const QNum *qn, uint64_t *val);
+uint64_t qnum_get_uint(const QNum *qn);
+
+double qnum_get_double(QNum *qn);
+
+char *qnum_to_string(QNum *qn);
+
+#endif /* QNUM_H */