‘u16’ does not name a type

CandyRedTele · 01-21-2013, 10:39 PM

Hello,

I'm trying to compile a cpp file which includes ad799x.h and I get this error :

ad799x.h:121:2: error: ‘u16’ does not name a type

I would like to know what should I include or link to be able to compile?

Thanks

corp769 · 01-21-2013, 11:00 PM

In your ad799x.h file, what is on line 121? And what is the purpose of your program/what does it do? By reading the error, it seems as you don't have a function, struct, etc properly defined. Also, if you could post more information about the header file, it would definitely help in further troubleshooting.

CandyRedTele · 01-22-2013, 09:03 AM

I'm trying to talk to the sensor AD7998, and to do that I'm supposed to use 'iio'.
The stucture is not defined in ad799x.h, that's why I think I have to include something else.

118
119 struct ad799x_platform_data {
120 u16 vref_mv;
121 };
122

You can find the header here :
http://wiki.analog.com/resources/too...98?force_rev=1

johnsfine · 01-22-2013, 09:59 AM

That code in ad799x.h is clearly assuming some previous include file defined u16 to be the same as __u16

But I can't see where in that project the definition of u16 is supposed to occur.

Somewhere there ought to be lines such as

Code:

typedef __u16 u16;
typedef __u8 u8;

But I'm not sure where those should be of whether that should be done in some way with more portability protection.

Another possibility is that you are supposed to include /usr/include/op_types.h

NevemTeve · 01-22-2013, 10:12 AM

Guess this source is meant for use in the kernel, where type 'u16' is defined. Try this:

Code:

#define __KERNEL__
#include <linux/types.h>
#include "ad799x.h"

CandyRedTele · 01-27-2013, 12:02 PM

I tried this :

#define __KERNEL__
#include <linux/types.h>
#include "ad799x.h"

But I got the same errors.
Any idea?

johnsfine · 01-27-2013, 12:09 PM

Maybe it varies by version, but the linux/types.h on my system does not declare u16 regardless of what #define's you might have.

The /usr/include/op_types.h does define u16 conditional on some #define.

Try looking at the .h file that you hope might solve your problem and see for yourself whether/when it declares u16

CandyRedTele · 01-27-2013, 01:00 PM

// This fixe the u16 error :
#define __KERNEL__
#include <asm-generic/int-ll64.h>
#include "ad799x.h"

g++ -I/usr/src/linux-headers-3.0.0-30-generic/include test.cpp
In file included from test.cpp:4:0:
ad799x.h:97:33: erreur: field ‘channel’ has incomplete type

channel is of type iio_chan_spec which is defined here in linux/iio/iio.h
But when I include it, I get Alot of errors

NevemTeve · 01-27-2013, 10:51 PM

Whenever you have a pre-processor related problem, ask cpp for help:

Code:

compilation: gcc <options> -c mysource.c -o mysource.o
pre-proc:    cpp <options> -dD mysource.c mysource.E

file mysource.E will contain the preprocessor's output.

NevemTeve · 01-28-2013, 02:54 AM

Made a few test that confirmed my original opinion: this source is meant for use in the kernel. It heavily depends on other kernel headers, not likely to be usable from user program.

mina86 · 01-28-2013, 07:13 AM

Why are you using this header in user space? It's a kernel driver.

In general “u16” type is never declared by Linux headers included by user space and for user space use “__u16” is used instead. If you find yourself in need to define __KERNEL__ than you're most likely doing something you should not be doing (or there is a problem with the header file).

CandyRedTele · 01-28-2013, 09:05 AM

Ok thanks for your answers!

I'm probably doing something wrong. I thougth the driver would be the interface between the user space and the kernel. If I'm not supposed to use the driver from user space, does that mean that I have to compile a kernel module in order to be able to use the sensor AD7998? Or is there a 'normal' way to do that from user space?

mina86 · 01-28-2013, 12:13 PM

Quote:

Originally Posted by CandyRedTele

I'm probably doing something wrong. I thougth the driver would be the interface between the user space and the kernel. If I'm not supposed to use the driver from user space, does that mean that I have to compile a kernel module in order to be able to use the sensor AD7998? Or is there a 'normal' way to do that from user space?

Since Linux 2.6.31 ad799x driver is in staging directory so you should use it instead of building the module itself.