Re: [Qemu-devel] [RfC PATCH] qdev: helper macros for properties

[Anthony Liguori]

Paul Brook wrote:
> On Wednesday 15 July 2009, Gerd Hoffmann wrote:
>   
> >   Hi,
> >
> > New revision of the helper macros for defining properties, going on top
> > of all other qdev patches posted today.
> >     
>
> IMO this should have been part of the initial properties rework, not a 
> followup change. Use of these macros should not be optional.
>   

For the common case, I'd rather something like the following.  Very GCC 
specific.

Regards,

Anthony Liguori

> Paul
>
>
>   

commit a7e2799c7c3c790c83e015b48ba34ac0975b93bb
Author: Anthony Liguori <address@hidden>
Date:   Thu Jul 16 22:16:02 2009 -0500

    Introduce macro for defining qdev properties.
    
    Signed-off-by: Anthony Liguori <address@hidden>

diff --git a/hw/escc.c b/hw/escc.c
index 9abd092..43230b9 100644
--- a/hw/escc.c
+++ b/hw/escc.c
@@ -952,21 +952,9 @@ static SysBusDeviceInfo escc_info = {
     .qdev.name  = "escc",
     .qdev.size  = sizeof(SerialState),
     .qdev.props = (Property[]) {
-        {
-            .name = "frequency",
-            .info = &qdev_prop_uint32,
-            .offset = offsetof(SerialState, frequency),
-        },
-        {
-            .name = "it_shift",
-            .info = &qdev_prop_uint32,
-            .offset = offsetof(SerialState, it_shift),
-        },
-        {
-            .name = "disabled",
-            .info = &qdev_prop_uint32,
-            .offset = offsetof(SerialState, disabled),
-        },
+        QDEV_PROP(SerialState, frequency),
+        QDEV_PROP(SerialState, it_shift),
+        QDEV_PROP(SerialState, disabled),
         {
             .name = "chrB",
             .info = &qdev_prop_ptr,
diff --git a/hw/qdev.h b/hw/qdev.h
index 11744fa..957ce22 100644
--- a/hw/qdev.h
+++ b/hw/qdev.h
@@ -143,6 +143,25 @@ void do_info_qtree(Monitor *mon);
 
 /*** qdev-properties.c ***/
 
+#define CHOOSE(a, b, c) __builtin_choose_expr(a, b, c)
+#define TYPES_COMPAT(a, b) __builtin_types_compatible_p(a, b)
+#define TYPEOF_FIELD(type, field) typeof(((type *)0)->field)
+#define BUILD_BUG() sizeof(char[-1])
+
+#define QDEV_PROP(type, field)                                     \
+    {                                                              \
+        .name = stringify(field),                                  \
+        .offset = offsetof(type, field),                           \
+        .info =                                                    \
+        CHOOSE(TYPES_COMPAT(TYPEOF_FIELD(type, field), uint32_t),  \
+        &qdev_prop_uint32,                                         \
+        CHOOSE(TYPES_COMPAT(TYPEOF_FIELD(type, field), int32_t),   \
+        &qdev_prop_uint32,                                         \
+        CHOOSE(TYPES_COMPAT(TYPEOF_FIELD(type, field), void *),    \
+        &qdev_prop_ptr,                                            \
+        NULL))),                                                   \
+    }
+
 extern PropertyInfo qdev_prop_uint16;
 extern PropertyInfo qdev_prop_uint32;
 extern PropertyInfo qdev_prop_hex32;