Le Fri, 20 Jun 2014 16:36:58 +0530,
Pranay Srivastava <pranjas@xxxxxxxxx> a écrit :
> You say here you will define the function else where if TEST_FUNCTION
> is defined
>
> > #ifdef TEST_FUNCTION
> > void test(int *value);
> > #else
> > static inline void test(int *value) { }
> > #endif
> >
> > test_ifdef.c:
> >
> > #include "test_ifdef.h"
> >
> But here you do on and define it any way. You must stick to the rule
> you created earlier. If you are defining it here then this must also
> be under the test of ifdef TEST_FUNCTION
> > void test(int *value)
> > {
> > *value += 1;
> > }
> >
Thank you Pranay for your answer. I understand this now.
But when i look at the kernel code, i don't see ifdef test around the
definition of the function. For example, i look for the function
"hiddev_hid_event":
In include/linux/hiddev.h:
#ifdef CONFIG_USB_HIDDEV
...
void hiddev_hid_event(struct hid_device *hid, struct hid_field *field,
struct hid_usage *usage, __s32 value);
...
#else
...
static inline void hiddev_hid_event(struct hid_device *hid, struct
hid_field *field, struct hid_usage *usage, __s32 value) { }
...
#endif
In drivers/hid/usbhid/hiddev.c:
/*
* This is where hid.c calls into hiddev to pass an event that occurred
over
* the interrupt pipe
*/
void hiddev_hid_event(struct hid_device *hid, struct hid_field *field,
struct hid_usage *usage, __s32 value)
{
unsigned type = field->report_type;
struct hiddev_usage_ref uref;
uref.report_type =
(type == HID_INPUT_REPORT) ? HID_REPORT_TYPE_INPUT :
((type == HID_OUTPUT_REPORT) ? HID_REPORT_TYPE_OUTPUT :
((type == HID_FEATURE_REPORT) ? HID_REPORT_TYPE_FEATURE :
0)); uref.report_id = field->report->id;
uref.field_index = field->index;
uref.usage_index = (usage - field->usage);
uref.usage_code = usage->hid;
uref.value = value;
hiddev_send_event(hid, &uref);
}
EXPORT_SYMBOL_GPL(hiddev_hid_event);
And in drivers/hid/hid-core.c:
...
if (hid->claimed & HID_CLAIMED_INPUT)
hidinput_hid_event(hid, field, usage, value);
if (hid->claimed & HID_CLAIMED_HIDDEV && interrupt &&
hid->hiddev_hid_event)
hid->hiddev_hid_event(hid, field, usage, value);
...
If i'm right. The function "hiddev_hid_event" is always defined in
"hiddev.c" whatever "CONFIG_USB_HIDDEV" is defined or not ?
How is it possible ?
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