Patchwork [02/29] Introduce QInt

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Submitter Luiz Capitulino
Date Aug. 13, 2009, 1:50 p.m.
Message ID <1250171428-29308-3-git-send-email-lcapitulino@redhat.com>
Download mbox | patch
Permalink /patch/31301/
State Superseded
Headers show

Comments

Luiz Capitulino - Aug. 13, 2009, 1:50 p.m.
QInt is a high-level data type that can be used to store integers
and perform type-safe conversions.

The following functions are available:

- qint_from_int()   Create a new QInt from an int
- qint_from_int64() Create a new QInt from an int64_t
- qint_to_int()     Export QInt to int
- qint_to_uint64()  Export QInt to uint64_t
- qint_to_uint32()  Export QInt to uint32_t

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 Makefile  |    1 +
 qint.c    |   81 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qint.h    |   27 ++++++++++++++++++++
 qobject.h |    1 +
 4 files changed, 110 insertions(+), 0 deletions(-)
 create mode 100644 qint.c
 create mode 100644 qint.h
Avi Kivity - Aug. 13, 2009, 1:55 p.m.
On 08/13/2009 04:50 PM, Luiz Capitulino wrote:
> +
> +/**
> + * qobject_to_qint(): Convert a QObject into a QInt
> + */
> +static inline QInt *qobject_to_qint(const QObject *obj)
> +{
> +    return container_of(obj, QInt, base);
> +}
> +
>    

It's worthwhile to check the type here and return NULL if not an 
integer.  That allows users to

    QInt *qi = qobject_to_qint(...);

    if (qi) {
        do something
    } else {
        error handling
    }

(this is equivalent to C++'s static_cast vs. dynamic_cast)
Luiz Capitulino - Aug. 13, 2009, 2:16 p.m.
On Thu, 13 Aug 2009 16:55:50 +0300
Avi Kivity <avi@redhat.com> wrote:

> On 08/13/2009 04:50 PM, Luiz Capitulino wrote:
> > +
> > +/**
> > + * qobject_to_qint(): Convert a QObject into a QInt
> > + */
> > +static inline QInt *qobject_to_qint(const QObject *obj)
> > +{
> > +    return container_of(obj, QInt, base);
> > +}
> > +
> >    
> 
> It's worthwhile to check the type here and return NULL if not an 
> integer.  That allows users to
> 
>     QInt *qi = qobject_to_qint(...);
> 
>     if (qi) {
>         do something
>     } else {
>         error handling
>     }
> 
> (this is equivalent to C++'s static_cast vs. dynamic_cast)

 OK.

 Note that QDict has high-level helpers like qdict_get_int()
that assumes that the stored key is a QInt.

 I was in doubt about how to fail. I chose to use assert() and
consider this a programming error.
Avi Kivity - Aug. 13, 2009, 2:43 p.m.
On 08/13/2009 05:16 PM, Luiz Capitulino wrote:
>
>   Note that QDict has high-level helpers like qdict_get_int()
> that assumes that the stored key is a QInt.
>
>   I was in doubt about how to fail. I chose to use assert() and
> consider this a programming error.
>    

We'll soon get qdicts from the monitor, so without an IDL we're forced 
on in-code checking.

Patch

diff --git a/Makefile b/Makefile
index 5279504..e296b5b 100644
--- a/Makefile
+++ b/Makefile
@@ -90,6 +90,7 @@  obj-y += buffered_file.o migration.o migration-tcp.o net.o qemu-sockets.o
 obj-y += qemu-char.o aio.o net-checksum.o savevm.o
 obj-y += msmouse.o ps2.o
 obj-y += qdev.o qdev-properties.o ssi.o
+obj-y += qint.o
 
 obj-$(CONFIG_BRLAPI) += baum.o
 obj-$(CONFIG_WIN32) += tap-win32.o
diff --git a/qint.c b/qint.c
new file mode 100644
index 0000000..6ac3499
--- /dev/null
+++ b/qint.c
@@ -0,0 +1,81 @@ 
+/*
+ * QInt data type.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+#include "qint.h"
+#include "qobject.h"
+#include "qemu-common.h"
+
+static QType qint_type;
+
+/**
+ * qint_from_int64(): Create a new QInt from an int64_t
+ *
+ * Return new reference.
+ */
+QInt *qint_from_int64(int64_t value)
+{
+    QInt *qi;
+
+    qi = qemu_malloc(sizeof(*qi));
+    qi->number = value;
+    qobject_init(QOBJECT(qi), &qint_type);
+
+    return qi;
+}
+
+/**
+ * qint_from_int(): Create a new QInt from an int
+ *
+ * Return new reference.
+ */
+QInt *qint_from_int(int value)
+{
+    return qint_from_int64(value);
+}
+
+/**
+ * qint_to_int(): Export QInt to int type
+ */
+int qint_to_int(const QInt *qi)
+{
+    return qi->number;
+}
+
+/**
+ * qint_to_uint64(): Export QInt to uint64_t type
+ */
+uint64_t qint_to_uint64(const QInt *qi)
+{
+    return qi->number;
+}
+
+/**
+ * qint_to_uint32(): Export QInt to uint32_t type
+ */
+uint32_t qint_to_uint32(const QInt *qi)
+{
+    return qi->number;
+}
+
+/**
+ * qint_destroy_obj(): Free all memory allocated by a
+ * QInt object
+ */
+static void qint_destroy_obj(QObject *obj)
+{
+    assert(obj != NULL);
+    qemu_free(qobject_to_qint(obj));
+}
+
+static QType qint_type = {
+    .code = QTYPE_QINT,
+    .destroy = qint_destroy_obj,
+};
diff --git a/qint.h b/qint.h
new file mode 100644
index 0000000..4c3b360
--- /dev/null
+++ b/qint.h
@@ -0,0 +1,27 @@ 
+#ifndef QINT_H
+#define QINT_H
+
+#include "qobject.h"
+#include "qemu-common.h"
+#include <stdint.h>
+
+typedef struct QInt {
+    QObject base;
+    int64_t number;
+} QInt;
+
+QInt *qint_from_int(int value);
+QInt *qint_from_int64(int64_t value);
+int qint_to_int(const QInt *qi);
+uint64_t qint_to_uint64(const QInt *qi);
+uint32_t qint_to_uint32(const QInt *qi);
+
+/**
+ * qobject_to_qint(): Convert a QObject into a QInt
+ */
+static inline QInt *qobject_to_qint(const QObject *obj)
+{
+    return container_of(obj, QInt, base);
+}
+
+#endif /* QINT_H */
diff --git a/qobject.h b/qobject.h
index 467f258..a5bbe61 100644
--- a/qobject.h
+++ b/qobject.h
@@ -40,6 +40,7 @@ 
 
 typedef enum {
     QTYPE_NONE,
+    QTYPE_QINT,
 } qtype_code;
 
 struct QObject;