printf the values of a macro

I'm having a problem figuring out how to printf the value of BD_ADDR
from this macro.

What I'm tring to do is get it to display a Bluetooth Address in the
format

"BD_ADDR = xx:xx:xx:xx:xx:xx"

Several people have told me that it's written wrong and breaks the
rules of C, but I did not write it, it's part of a bluetooth lib

I can't do anything about how it's written, I just want to printf the
value of BD_ADDR but I have never before worked with a stucture like
this.


Below is a snippet of the lib I'm trying to work with.


/*
* Copyright (c) 2003 EISLAB, Lulea University of Technology.
* All rights reserved.
*
* This file is part of the lwBT Bluetooth stack.
*
* Author: Conny Ohult <conny@sm.luth.se>
*
*/

#ifndef __BD_ADDR_H__
#define __BD_ADDR_H__

struct bd_addr {
u8 addr[6];
};

#define BD_ADDR_LEN 6

#define BD_ADDR_ANY (&(struct bd_addr){{0,0,0,0,0,0}})
#define BD_ADDR_LOCAL (&(struct bd_addr){{0,0,0,0xff,0xff,0xff}})

#define BD_ADDR(bdaddr, a, b, c, d, e, f) do{ \
(bdaddr)->addr[0] = a; \
(bdaddr)->addr[1] = b; \
(bdaddr)->addr[2] = c; \
(bdaddr)->addr[3] = d; \
(bdaddr)->addr[4] = e; \
(bdaddr)->addr[5] = f; }while(0)

In article <4qs3n5hhdgtacqcgjguatko6uset2m6uv2@4ax.com>, idontuse@email.com writes:

> "BD_ADDR = xx:xx:xx:xx:xx:xx"

> struct bd_addr {
> u8 addr[6];
> };


int
print_bd_addr(FILE *f, const struct bd_addr *p)
{
return fprintf(f, "BD_ADDR = %02x:%02x:%02x:%02x:%02x:%02x",
(unsigned)p->addr[0], (unsigned)p->addr[1],
(unsigned)p->addr[2], (unsigned)p->addr[3],
(unsigned)p->addr[4], (unsigned)p->addr[5]
);
}

If this is what you want.

Cheers,
lacos

On 10 Feb 2010 01:28:34 +0100, lacos@ludens.elte.hu (Ersek, Laszlo)
wrote:

>In article <4qs3n5hhdgtacqcgjguatko6uset2m6uv2@4ax.com>, idontuse@email.com writes:
>
>> "BD_ADDR = xx:xx:xx:xx:xx:xx"
>
>> struct bd_addr {
>> u8 addr[6];
>> };
>
>
>int
>print_bd_addr(FILE *f, const struct bd_addr *p)
>{
> return fprintf(f, "BD_ADDR = %02x:%02x:%02x:%02x:%02x:%02x",
> (unsigned)p->addr[0], (unsigned)p->addr[1],
> (unsigned)p->addr[2], (unsigned)p->addr[3],
> (unsigned)p->addr[4], (unsigned)p->addr[5]
> );
>}
>
>If this is what you want.
>
>Cheers,
>lacos


Hi lacos,

Thanks for the post.

Sorry for my ignorance, but wouyld I put this inside the lib I'm
including, or would I put this in my main.c ?

No matter where I put it, would I just:

int ret;
ret = print_bd_addr();

to use it?

As you can tell, I don't do a whole lot of c programming and this is
the first time I've had to use any type of structure/macro.

Thanks!
Jason

In article <c514n5hhtj10hej94njnhq52670cbpdep6@4ax.com>, idontuse@email.com writes:
> On 10 Feb 2010 01:28:34 +0100, lacos@ludens.elte.hu (Ersek, Laszlo)
> wrote:
>
>>In article <4qs3n5hhdgtacqcgjguatko6uset2m6uv2@4ax.com>, idontuse@email.com writes:
>>
>>> "BD_ADDR = xx:xx:xx:xx:xx:xx"
>>
>>> struct bd_addr {
>>> u8 addr[6];
>>> };
>>
>>
>>int
>>print_bd_addr(FILE *f, const struct bd_addr *p)
>>{
>> return fprintf(f, "BD_ADDR = %02x:%02x:%02x:%02x:%02x:%02x",
>> (unsigned)p->addr[0], (unsigned)p->addr[1],
>> (unsigned)p->addr[2], (unsigned)p->addr[3],
>> (unsigned)p->addr[4], (unsigned)p->addr[5]
>> );
>>}

> No matter where I put it, would I just:
>
> int ret;
> ret = print_bd_addr();
>
> to use it?


Please describe what you're trying to achieve.

Cheers,
lacos

An example of using Ersek's Function:

int main(void)
{
FILE *file = fopen("output.txt","wb");
struct bd_addr BD_ADDR;

BD_ADDR->addr[0] = 0xff;
BD_ADDR->addr[1] = 0xff;
BD_ADDR->addr[2] = 0xff;
BD_ADDR->addr[3] = 0xff;
BD_ADDR->addr[4] = 0xff;
BD_ADDR->addr[5] = 0xff;

printf_bd_addr(file,&BD_ADDR);
fclose(file);
return 0;
}

int print_bd_addr(FILE *f, const struct bd_addr *p)
{
return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
(unsigned char)p->addr[0],(unsigned char)p->addr[1],
(unsigned char)p->addr[2],(unsigned char)p->addr[3],
(unsigned char)p->addr[4],(unsigned char)p->addr[5]
);

}

On Feb 9, 5:02*pm, idont...@email.com wrote:
> On 10 Feb 2010 01:28:34 +0100, la...@ludens.elte.hu (Ersek, Laszlo)
> wrote:
>
>
>
> >In article <4qs3n5hhdgtacqcgjguatko6uset2m6...@4ax.com>, idont...@email.com writes:
>
> >> "BD_ADDR = xx:xx:xx:xx:xx:xx"
>
> >> struct bd_addr {
> >> * u8 addr[6];
> >> };
>
> >int
> >print_bd_addr(FILE *f, const struct bd_addr *p)
> >{
> > *return fprintf(f, "BD_ADDR = %02x:%02x:%02x:%02x:%02x:%02x",
> > * * *(unsigned)p->addr[0], (unsigned)p->addr[1],
> > * * *(unsigned)p->addr[2], (unsigned)p->addr[3],
> > * * *(unsigned)p->addr[4], (unsigned)p->addr[5]
> > *);
> >}
>
> >If this is what you want.
>
> >Cheers,
> >lacos
>
> Hi lacos,
>
> Thanks for the post.
>
> Sorry for my ignorance, but wouyld I put this inside the lib I'm
> including, or would I put this in my main.c ?
>
> No matter where I put it, would I just:
>
> * int ret;
> * ret = print_bd_addr();
>
> to use it?
>
> As you can tell, I don't do a whole lot of c programming and this is
> the first time I've had to use any type of structure/macro.
>
> Thanks!
> Jason

An example of using Ersek's Function:

int main(void)
{
FILE *file = fopen("output.txt","wb");
struct bd_addr *BD_ADDR;

BD_ADDR->addr[0] = 0xff;
BD_ADDR->addr[1] = 0xff;
BD_ADDR->addr[2] = 0xff;
BD_ADDR->addr[3] = 0xff;
BD_ADDR->addr[4] = 0xff;
BD_ADDR->addr[5] = 0xff;

printf_bd_addr(file,&BD_ADDR);
fclose(file);
return 0;

}

int print_bd_addr(FILE *f, const struct bd_addr *p)
{
return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
(unsigned char)p->addr[0],(unsigned char)p->addr[1],
(unsigned char)p->addr[2],(unsigned char)p->addr[3],
(unsigned char)p->addr[4],(unsigned char)p->addr[5]
);
}

J wrote:
> An example of using Ersek's Function:
>
> int print_bd_addr(FILE *f, const struct bd_addr *p)
> {
> return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
> (unsigned char)p->addr[0],(unsigned char)p->addr[1],
> (unsigned char)p->addr[2],(unsigned char)p->addr[3],
> (unsigned char)p->addr[4],(unsigned char)p->addr[5]
> );
> }

Why are you casting to unsigned char?

--
Ian Collins

On Feb 9, 6:00*pm, Ian Collins <ian-n...@hotmail.com> wrote:
> J wrote:
> > An example of using Ersek's Function:
>
> > int print_bd_addr(FILE *f, const struct bd_addr *p)
> > {
> > * return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
> > * * * (unsigned char)p->addr[0],(unsigned char)p->addr[1],
> > * * * (unsigned char)p->addr[2],(unsigned char)p->addr[3],
> > * * * (unsigned char)p->addr[4],(unsigned char)p->addr[5]
> > * );
> > }
>
> Why are you casting to unsigned char?
>
> --
> Ian Collins

I wasn't sure what type u8 was until I found this definition using
Google Search:
typedef U8 unsigned char
It could be u8.

I must see the definition of u8 in the library. I assumed it was
unsigned char.

On 10 Feb 2010 02:18:00 +0100, lacos@ludens.elte.hu (Ersek, Laszlo)
wrote:
....
>
>
>Please describe what you're trying to achieve.
>
>Cheers,
>lacos



Hi lacos,

OK here's my story.

I'm obviously a beginning c programmer; hence my probably explaining
this wrong, but here's my best shot.


I'm editing a main.c that I created that has an #include "bte.h"

bte.h has an include of #include "bd_addr.h"

Inside bd_addr.h is the BD_ADDR function that has the bluetooth
address the system found on boot-up.


The main.c program I am writting currently compiles OK, but I need to
exact one more piece of information that it has access to, the
bluetooth address of the attached device.

(The device is a remote controller for a video game (a wii remote))

I was able to get all of the bluetooth functions I'm after to work
just fine, but I need to add a feature where I press the "B" Button
and it will display the attached remote's BlueTooth address.

There are many other functions, such as button_pressed, battery level
and so on that I was able to display with little trouble, but when I
came across this...macro I guess it is... I got stuck.


So, in closing, what I want to do is be able to call one of the
built-in functions of bte_address.h and get the BlueTooth Address and
printf it on the screen.

Below are links to the two includes that are part of my main.c


http://pastie.org/817526 = the entire bte.h

http://pastie.org/817534 = the entire bd_addr.h

On Feb 9, 6:00*pm, Ian Collins <ian-n...@hotmail.com> wrote:
> J wrote:
> > An example of using Ersek's Function:
>
> > int print_bd_addr(FILE *f, const struct bd_addr *p)
> > {
> > * return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
> > * * * (unsigned char)p->addr[0],(unsigned char)p->addr[1],
> > * * * (unsigned char)p->addr[2],(unsigned char)p->addr[3],
> > * * * (unsigned char)p->addr[4],(unsigned char)p->addr[5]
> > * );
> > }
>
> Why are you casting to unsigned char?
>
> --
> Ian Collins

An example of using Ersek's Function:

int main(void)
{
FILE *file = fopen("output.txt","wb");
struct bd_addr *BD_ADDR;

BD_ADDR->addr[0] = 0xff;
BD_ADDR->addr[1] = 0xff;
BD_ADDR->addr[2] = 0xff;
BD_ADDR->addr[3] = 0xff;
BD_ADDR->addr[4] = 0xff;
BD_ADDR->addr[5] = 0xff;

printf_bd_addr(file,&BD_ADDR);
fclose(file);
return 0;

}
int print_bd_addr(FILE *f, const struct bd_addr *p)
{
return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
(unsigned)p->addr[0],(unsigned)p->addr[1],
(unsigned)p->addr[2],(unsigned)p->addr[3],
(unsigned)p->addr[4],(unsigned)p->addr[5]
);
}

On Tue, 9 Feb 2010 18:20:12 -0800 (PST), J <seaworthyjeremy@gmail.com>
wrote:

>On Feb 9, 6:00*pm, Ian Collins <ian-n...@hotmail.com> wrote:
>> J wrote:
>> > An example of using Ersek's Function:
>>
>> > int print_bd_addr(FILE *f, const struct bd_addr *p)
>> > {
>> > * return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
>> > * * * (unsigned char)p->addr[0],(unsigned char)p->addr[1],
>> > * * * (unsigned char)p->addr[2],(unsigned char)p->addr[3],
>> > * * * (unsigned char)p->addr[4],(unsigned char)p->addr[5]
>> > * );

>> > }
>>
>> Why are you casting to unsigned char?
>>
>> --
>> Ian Collins
>
>An example of using Ersek's Function:
>
>int main(void)
>{
> FILE *file = fopen("output.txt","wb");
> struct bd_addr *BD_ADDR;
>
> BD_ADDR->addr[0] = 0xff;
> BD_ADDR->addr[1] = 0xff;
> BD_ADDR->addr[2] = 0xff;
> BD_ADDR->addr[3] = 0xff;
> BD_ADDR->addr[4] = 0xff;
> BD_ADDR->addr[5] = 0xff;
>
> printf_bd_addr(file,&BD_ADDR);
> fclose(file);
> return 0;
>
>}
>int print_bd_addr(FILE *f, const struct bd_addr *p)
>{
> return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
> (unsigned)p->addr[0],(unsigned)p->addr[1],
> (unsigned)p->addr[2],(unsigned)p->addr[3],
> (unsigned)p->addr[4],(unsigned)p->addr[5]
> );
>}


Thanks J,

I really appreciate your showing how this works... I would have never
figuered it out on my own.

I'm getting ready to give this a try.
One question though..

With my limited knowledge of, it looks like this is going to write the
value to a text file called output.txt ?

If so, what do I need to change to get it to just printf it to the
output window?

On Tue, 09 Feb 2010 20:39:18 -0800, idontuse@email.com wrote:

>On Tue, 9 Feb 2010 18:20:12 -0800 (PST), J <seaworthyjeremy@gmail.com>
>wrote:
>
>>On Feb 9, 6:00*pm, Ian Collins <ian-n...@hotmail.com> wrote:
>>> J wrote:
>>> > An example of using Ersek's Function:
>>>
>>> > int print_bd_addr(FILE *f, const struct bd_addr *p)
>>> > {
>>> > * return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
>>> > * * * (unsigned char)p->addr[0],(unsigned char)p->addr[1],
>>> > * * * (unsigned char)p->addr[2],(unsigned char)p->addr[3],
>>> > * * * (unsigned char)p->addr[4],(unsigned char)p->addr[5]
>>> > * );
>
>>> > }
>>>
>>> Why are you casting to unsigned char?
>>>
>>> --
>>> Ian Collins
>>
>>An example of using Ersek's Function:
>>
>>int main(void)
>>{
>> FILE *file = fopen("output.txt","wb");
>> struct bd_addr *BD_ADDR;
>>
>> BD_ADDR->addr[0] = 0xff;
>> BD_ADDR->addr[1] = 0xff;
>> BD_ADDR->addr[2] = 0xff;
>> BD_ADDR->addr[3] = 0xff;
>> BD_ADDR->addr[4] = 0xff;
>> BD_ADDR->addr[5] = 0xff;
>>
>> printf_bd_addr(file,&BD_ADDR);
>> fclose(file);
>> return 0;
>>
>>}
>>int print_bd_addr(FILE *f, const struct bd_addr *p)
>>{
>> return fprintf(f,"BD_ADDR = %2x:%2x:%2x:%2x:%2x:%2x",
>> (unsigned)p->addr[0],(unsigned)p->addr[1],
>> (unsigned)p->addr[2],(unsigned)p->addr[3],
>> (unsigned)p->addr[4],(unsigned)p->addr[5]
>> );
>>}
>
>
>Thanks J,
>
>I really appreciate your showing how this works... I would have never
>figuered it out on my own.
>
>I'm getting ready to give this a try.
>One question though..
>
>With my limited knowledge of, it looks like this is going to write the
>value to a text file called output.txt ?
>
>If so, what do I need to change to get it to just printf it to the
>output window?
>


Well, it compiles with a few warnings, so I must be getting closer...



main.c
l:/devkitPro/mrc/src/source/main.c: In function 'get_bt_info':
l:/devkitPro/mrc/src/source/main.c:359: warning: passing argument 2 of
'print_bd_addr' from incompatible pointer type
l:/devkitPro/mrc/src/source/main.c:283: note: expected 'const struct
bd_addr *' but argument is of type 'struct bd_addr **'
l:/devkitPro/mrc/src/source/main.c:288: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:288: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:287: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:287: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:286: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:286: warning: dereferencing pointer
'BD_ADDR.56' does break strict-aliasing rules
l:/devkitPro/mrc/src/source/main.c:359: note: initialized from here
tools.c
linking ... src.elf
output ... src.dol

> Process Exit Code: 0
> Time Taken: 00:17

idontuse@email.com writes:

<snip>
> Well, it compiles with a few warnings, so I must be getting closer...
>
> main.c
> l:/devkitPro/mrc/src/source/main.c: In function 'get_bt_info':
> l:/devkitPro/mrc/src/source/main.c:359: warning: passing argument 2 of
> 'print_bd_addr' from incompatible pointer type
> l:/devkitPro/mrc/src/source/main.c:283: note: expected 'const struct
> bd_addr *' but argument is of type 'struct bd_addr **'
> l:/devkitPro/mrc/src/source/main.c:288: warning: dereferencing pointer
> 'BD_ADDR.56' does break strict-aliasing rules

Some of these are very serious. You can't consider then to be "a few
warnings". It is in the nature of C that a very serious error can go
undetected by the compiler. To get a warning is a bonus, and they
would not be ignored unless you know that it is safe to do so.

--
Ben.

In article <te34n556tav479lc8c7klcbsmgcql6ooge@4ax.com>, idontuse@email.com writes:

> I'm editing a main.c that I created that has an #include "bte.h"
>
> bte.h has an include of #include "bd_addr.h"
>
> Inside bd_addr.h is the BD_ADDR function that has the bluetooth
> address the system found on boot-up.


> http://pastie.org/817526 = the entire bte.h
>
> http://pastie.org/817534 = the entire bd_addr.h

BD_ADDR is a function-like macro defined in "bd_addr.h", and it doesn't
return the boot-up bluetooth address or some such -- it fills in a
programmer-supplied "struct bt_addr" object with the six
programmer-supplied octets. In other words, it's a convenience macro for
assigning a value to a "bluetooth address" object.


> So, in closing, what I want to do is be able to call one of the
> built-in functions of bte_address.h and get the BlueTooth Address and
> printf it on the screen.

I've never seen this library before, but from the structure declarations
and function declarations (prototypes) in "bte.h", I'd try something
like this:

#define MAXDEVICES 10u

/* Device identifier of the device we care about, or whatever. */
static const u8 mycod[] = { 0xAAu, 0xBBu, 0xCCu };

/*
Return value:
negative : device found, print error
0 : no device found / device not found
positive : device found and printed (no trailing newline)
*/
static int
print_it(void)
{
u8 max_cnt,
flush;
s32 inq_res;
struct inquiry_info info[MAXDEVICES];

/* Set up as appropriate, for example: */
max_cnt = MAXDEVICES;
flush = ...;

inq_res = bte_inquiry(info, max_cnt, flush);

/*
Check inq_res. I guess it returns the number of devices found,
or a negative value in case of error. If it succeeds, search for
the device you're interested in based on "cod" or whatever, and
print its address.
*/

if (0 < inq_res) {
unsigned devidx;

for (devidx = 0u; devidx < (unsigned)inq_res; ++devidx) {
if (0 == memcmp(info[devidx].cod, mycod, sizeof mycod)) {
const u8 *addr;

addr = info[devidx].bdaddr.addr;
return fprintf(stdout, "%02x:%02x:%02x:%02x:%02x:%02x",
(unsigned)addr[0], (unsigned)addr[1], (unsigned)addr[2],
(unsigned)addr[3], (unsigned)addr[4], (unsigned)addr[5]);
}
}
}

return 0;
}

As mentioned above, print_it() doesn't print a trailing newline after
the address. It doesn't flush stdout either. (I'm not even sure if
you've meant the standard output stream by "printing to the screen".)

Cheers,
lacos

idontuse@email.com wrote:
> I'm having a problem figuring out how to printf the value of BD_ADDR
> from this macro.
>
> What I'm tring to do is get it to display a Bluetooth Address in the
> format
>
> "BD_ADDR = xx:xx:xx:xx:xx:xx"
>
> Several people have told me that it's written wrong and breaks the
> rules of C, but I did not write it, it's part of a bluetooth lib

Sometimes there are good reasons for non-portable libraries to do
strange things. I'm not going to look look at the details...

> I can't do anything about how it's written, I just want to printf the
> value of BD_ADDR but I have never before worked with a stucture like
> this.

You just deal with the individual components rather than doing the thing
as a whole.

> Below is a snippet of the lib I'm trying to work with.

<snip>

> struct bd_addr {
> u8 addr[6];
> };

<snip>

Depends on how you are using this. If you have something like...

struct bd_addr myaddr;

You can access the elements as
myaddr.addr[0]
etc.

Then you can print them as normal and put in the colons yourself.
Remember that u8 is probably a typedef for "unsigned char" so you need
to select your format specifiers appropriately.
--
Flash Gordon