Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
Thanks Roman, I didn't know that this was possible with [oscformat] and [oscparse]. Thanks all the friends here, I finally succeed writing my own external. Not a perfect one, but solved my problem for now. Roman Haefeli , 7 Nis 2019 Paz, 18:54 tarihinde şunu yazdı: > Hi Arda > > On Fri, 2019-04-05 at 16:00 +0300, Arda Eden wrote: > > > > I am reading the udp data with [netreceive] succesfully and able to > > reach any value I need. Now trying to find a way to combine these > > (big endian) sequential 4 bytes in order to get the resulting 32 bit > > floating point number. A little advice would speed me up. > > > Don't know if you need to do it in your own external. If you do the > message parsing in Pd (as opposed to a dedicated external), check > attached patch. It converts between floats and 4-byte-lists. Probably > not efficient, when converting tons of numbers, but easy if you're > looking for a quick'n'dirty solution. > > Roman > ___ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list > -- Arda EDEN Yıldız Teknik Üniversitesi Sanat ve Tasarım Fakültesi Müzik ve Sahne Sanatları Bölümü Duysal (Ses) Sanatları Tasarımı Programı İstanbul/Türkiye Yildiz Technical University Faculty of Art and Design Department of Music and Performing Arts Audio Design Program Istanbul/Turkey ___ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
Hi Arda On Fri, 2019-04-05 at 16:00 +0300, Arda Eden wrote: > > I am reading the udp data with [netreceive] succesfully and able to > reach any value I need. Now trying to find a way to combine these > (big endian) sequential 4 bytes in order to get the resulting 32 bit > floating point number. A little advice would speed me up. Don't know if you need to do it in your own external. If you do the message parsing in Pd (as opposed to a dedicated external), check attached patch. It converts between floats and 4-byte-lists. Probably not efficient, when converting tons of numbers, but easy if you're looking for a quick'n'dirty solution. Roman #N canvas 119 99 443 367 10; #N canvas 0 99 387 150 float2bytes 0; #X obj 34 64 oscformat l; #X obj 34 87 list split 8; #X obj 34 38 inlet; #X obj 68 120 outlet; #X connect 0 0 1 0; #X connect 1 1 3 0; #X connect 2 0 0 0; #X restore 109 97 pd float2bytes; #N canvas 0 99 409 269 bytes2float 0; #X msg 102 90 47 108 0 0 44 102 0 0; #X obj 33 133 list prepend; #X obj 102 59 loadbang; #X obj 33 156 oscparse; #X obj 33 179 list trim; #X obj 33 202 route l; #X obj 33 32 inlet; #X obj 33 227 outlet; #X connect 0 0 1 1; #X connect 1 0 3 0; #X connect 2 0 0 0; #X connect 3 0 4 0; #X connect 4 0 5 0; #X connect 5 0 7 0; #X connect 6 0 1 0; #X restore 109 215 pd bytes2float; #X obj 109 138 t a a; #X obj 136 165 print BYTES; #X obj 109 300 print FLOAT; #X floatatom 109 32 10 0 0 0 - - -; #X connect 0 0 2 0; #X connect 1 0 4 0; #X connect 2 0 1 0; #X connect 2 1 3 0; #X connect 5 0 0 0; signature.asc Description: This is a digitally signed message part ___ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
Absolutely !!! Copying memory 3 times is not efficient already. :) Thanks Martin. I just need to get 2 or a few skeleton segments for a contemporary dance performance, and this way, I will solve my problem temporarily. Xsens may not be a widely used system, but it works great. I think it deserves an Xsens to OSC converter PD object some day, But this exceeds my programming skills (as you will get it from my code above :) ). Just remembered now: Xsens has a fps rate of 60-240 and a very big amount of data is transferred very fast over the network. When I listened the packages with [netreceive] and printed them on the console, PD Vanilla 0.49.1 crashed. But it worked with Purr-data. Indeed, I didn't have time to test it in detail. Maybe the problem was with my computer. Just for info. Thank you my friends. ___ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
On Sat, Apr 6, 2019 at 10:54 AM Arda Eden wrote:
> With this method, I got the compiler warning about breaking the strict
> aliasing rule:
> uint8_t bytes[4] = {12, 34, 56, 78};
> float f = *(float*)bytes;
>
> Yes, modern c doesn't like type punning.
> This is my code, and for now, it is working properly. But I am not sure if
> this is an efficient way or not.
>
> typedef struct _xsensparse
> {
> t_object x_obj;
> uint8_t wrd[4];
> t_float o;
> t_outlet *f1_out, *f2_out;
> } t_xsensparse;
>
> static void xsensparse_list(t_xsensparse *x, t_symbol *s, int argc, t_atom
> *argv)
> {
> for(int i=0; i x->wrd[i]=(uint8_t)atom_getfloat(argv+3-i);
> memcpy(>o, >wrd, 4);
> }
> post("%f", x->o);
> outlet_float(x->f1_out, x->o);
> }
>
>
I think the memcpy statement should be outside the for loop. As it is, it
operates the first three times uselessly.
Using a union would be a bit more efficient as it doesn't copy any memory.
Martin
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Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
With this method, I got the compiler warning about breaking the strict
aliasing rule:
uint8_t bytes[4] = {12, 34, 56, 78};
float f = *(float*)bytes;
This is my code, and for now, it is working properly. But I am not sure if
this is an efficient way or not.
typedef struct _xsensparse
{
t_object x_obj;
uint8_t wrd[4];
t_float o;
t_outlet *f1_out, *f2_out;
} t_xsensparse;
static void xsensparse_list(t_xsensparse *x, t_symbol *s, int argc, t_atom
*argv)
{
for(int i=0; iwrd[i]=(uint8_t)atom_getfloat(argv+3-i);
memcpy(>o, >wrd, 4);
}
post("%f", x->o);
outlet_float(x->f1_out, x->o);
}
Martin Peach , 6 Nis 2019 Cmt, 17:36 tarihinde şunu
yazdı:
> On Sat, Apr 6, 2019 at 10:06 AM Christof Ressi
> wrote:
>
>> While type punning through unions is allowed in C, the only way which
>> works in both C and C++ (without breaking the strict aliasing rule) is
>> using memcpy. In such case, the call to memcpy will completely optimized
>> away by every decent compiler.
>>
>>
> But Pd is written in c, so no problem. How does the memcpy thing work? It
> is also ANSI c. To m it looks just as 'dangerous' as the union method,
> which I wouldn't call type-punning. 'Raw' type punning would be like:
> uint8_t bytes[4] = {12, 34, 56, 78};
> float f = *(float*)bytes;
> But isn't that basically the same as what memcpy does?
>
>
> Martin
>
> ___
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Audio Design Program
Istanbul/Turkey
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Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
On Sat, Apr 6, 2019 at 10:06 AM Christof Ressi
wrote:
> While type punning through unions is allowed in C, the only way which
> works in both C and C++ (without breaking the strict aliasing rule) is
> using memcpy. In such case, the call to memcpy will completely optimized
> away by every decent compiler.
>
>
But Pd is written in c, so no problem. How does the memcpy thing work? It
is also ANSI c. To m it looks just as 'dangerous' as the union method,
which I wouldn't call type-punning. 'Raw' type punning would be like:
uint8_t bytes[4] = {12, 34, 56, 78};
float f = *(float*)bytes;
But isn't that basically the same as what memcpy does?
Martin
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Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
While type punning through unions is allowed in C, the only way which works in
both C and C++ (without breaking the strict aliasing rule) is using memcpy. In
such case, the call to memcpy will completely optimized away by every decent
compiler.
> Gesendet: Samstag, 06. April 2019 um 11:28 Uhr
> Von: "cyrille henry"
> An: "pd-list@lists.iem.at"
> Betreff: Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
>
> hello,
> I think a better way (that did not need to copy the data) is to use a union :
> i.e. 2 different type can be declared in the same memory space.
> something like :
>
> // union type definition
> union int_and_float {
>int8_t my_int[4];
>float my_float;
> };
>
> int_and_float my_int_and_float; // declaration of a variable of this type
>
> my_int_and_float.my_int[0] = 0; // value assignation
> my_int_and_float.my_int[1] = 0;
> my_int_and_float.my_int[2] = 0;
> my_int_and_float.my_int[3] = 0;
>
> the float data should be in : my_int_and_float.my_float;
>
> I did not test this code, It will certainly contain syntaxes errors, but
> you'll find the way to correct it on internet...
>
>
> An other solution is to use bitwise operator :
>
> my_float = (byte1 << 24) & (byte2 << 16) & (byte3 << 8) & byte4;
>
> cheers
> Cyrille
>
> Le 05/04/2019 à 19:04, Arda Eden a écrit :
> > I found a method using "memcpy". Seems like it is working for now.
> >
> > Arda Eden mailto:ardae...@gmail.com>>, 5 Nis 2019 Cum,
> > 16:00 tarihinde şunu yazdı:
> >
> > Hi,
> > I am trying to write a Pure Data external for getting real time motion
> > capture values from an Xsens system. According to the manual
> > (https://xsens.com/download/usermanual/3DBM/MVN_real-time_network_streaming_protocol_specification.pdf),
> > the x, y and z coordinates of the skeleton segment positions are
> > transferred over network (udp) as sequential 4 bytes (32 bit floating point
> > - big endian).
> >
> > I am reading the udp data with [netreceive] succesfully and able to
> > reach any value I need. Now trying to find a way to combine these (big
> > endian) sequential 4 bytes in order to get the resulting 32 bit floating
> > point number. A little advice would speed me up.
> >
> > By the way, I studied the [oscparse] source. It was very helpful in
> > most ways but also a little complicated too.
> >
> > Thanks already.
> >
> > --
> > Arda EDEN
> > Yıldız Teknik Üniversitesi
> > Sanat ve Tasarım Fakültesi
> > Müzik ve Sahne Sanatları Bölümü
> > Duysal (Ses) Sanatları Tasarımı Programı
> > İstanbul/Türkiye
> >
> > Yildiz Technical University
> > Faculty of Art and Design
> > Department of Music and Performing Arts
> > Audio Design Program
> > Istanbul/Turkey
> >
> >
> >
> > --
> > Arda EDEN
> > Yıldız Teknik Üniversitesi
> > Sanat ve Tasarım Fakültesi
> > Müzik ve Sahne Sanatları Bölümü
> > Duysal (Ses) Sanatları Tasarımı Programı
> > İstanbul/Türkiye
> >
> > Yildiz Technical University
> > Faculty of Art and Design
> > Department of Music and Performing Arts
> > Audio Design Program
> > Istanbul/Turkey
> >
> > ___
> > Pd-list@lists.iem.at mailing list
> > UNSUBSCRIBE and account-management ->
> > https://lists.puredata.info/listinfo/pd-list
> >
>
>
>
> ___
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Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
On Sat, 2019-04-06 at 11:28 +0200, cyrille henry wrote: > > > An other solution is to use bitwise operator : > > my_float = (byte1 << 24) & (byte2 << 16) & (byte3 << 8) & byte4; From what I understand, the result is not a 32 bit floating point number, but a 32 bit unsigned int (assuming that each byte is an unsigned 8 bit int). Roman signature.asc Description: This is a digitally signed message part ___ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
hello,
I think a better way (that did not need to copy the data) is to use a union :
i.e. 2 different type can be declared in the same memory space.
something like :
// union type definition
union int_and_float {
int8_t my_int[4];
float my_float;
};
int_and_float my_int_and_float; // declaration of a variable of this type
my_int_and_float.my_int[0] = 0; // value assignation
my_int_and_float.my_int[1] = 0;
my_int_and_float.my_int[2] = 0;
my_int_and_float.my_int[3] = 0;
the float data should be in : my_int_and_float.my_float;
I did not test this code, It will certainly contain syntaxes errors, but you'll
find the way to correct it on internet...
An other solution is to use bitwise operator :
my_float = (byte1 << 24) & (byte2 << 16) & (byte3 << 8) & byte4;
cheers
Cyrille
Le 05/04/2019 à 19:04, Arda Eden a écrit :
I found a method using "memcpy". Seems like it is working for now.
Arda Eden mailto:ardae...@gmail.com>>, 5 Nis 2019 Cum,
16:00 tarihinde şunu yazdı:
Hi,
I am trying to write a Pure Data external for getting real time motion
capture values from an Xsens system. According to the manual
(https://xsens.com/download/usermanual/3DBM/MVN_real-time_network_streaming_protocol_specification.pdf),
the x, y and z coordinates of the skeleton segment positions are transferred
over network (udp) as sequential 4 bytes (32 bit floating point - big endian).
I am reading the udp data with [netreceive] succesfully and able to reach
any value I need. Now trying to find a way to combine these (big endian)
sequential 4 bytes in order to get the resulting 32 bit floating point number.
A little advice would speed me up.
By the way, I studied the [oscparse] source. It was very helpful in most
ways but also a little complicated too.
Thanks already.
--
Arda EDEN
Yıldız Teknik Üniversitesi
Sanat ve Tasarım Fakültesi
Müzik ve Sahne Sanatları Bölümü
Duysal (Ses) Sanatları Tasarımı Programı
İstanbul/Türkiye
Yildiz Technical University
Faculty of Art and Design
Department of Music and Performing Arts
Audio Design Program
Istanbul/Turkey
--
Arda EDEN
Yıldız Teknik Üniversitesi
Sanat ve Tasarım Fakültesi
Müzik ve Sahne Sanatları Bölümü
Duysal (Ses) Sanatları Tasarımı Programı
İstanbul/Türkiye
Yildiz Technical University
Faculty of Art and Design
Department of Music and Performing Arts
Audio Design Program
Istanbul/Turkey
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Re: [PD] Getting 32 bit floating point number from 4 sequential bytes
I found a method using "memcpy". Seems like it is working for now. Arda Eden , 5 Nis 2019 Cum, 16:00 tarihinde şunu yazdı: > Hi, > I am trying to write a Pure Data external for getting real time motion > capture values from an Xsens system. According to the manual ( > https://xsens.com/download/usermanual/3DBM/MVN_real-time_network_streaming_protocol_specification.pdf), > the x, y and z coordinates of the skeleton segment positions are > transferred over network (udp) as sequential 4 bytes (32 bit floating point > - big endian). > > I am reading the udp data with [netreceive] succesfully and able to reach > any value I need. Now trying to find a way to combine these (big endian) > sequential 4 bytes in order to get the resulting 32 bit floating point > number. A little advice would speed me up. > > By the way, I studied the [oscparse] source. It was very helpful in most > ways but also a little complicated too. > > Thanks already. > > -- > Arda EDEN > Yıldız Teknik Üniversitesi > Sanat ve Tasarım Fakültesi > Müzik ve Sahne Sanatları Bölümü > Duysal (Ses) Sanatları Tasarımı Programı > İstanbul/Türkiye > > Yildiz Technical University > Faculty of Art and Design > Department of Music and Performing Arts > Audio Design Program > Istanbul/Turkey > -- Arda EDEN Yıldız Teknik Üniversitesi Sanat ve Tasarım Fakültesi Müzik ve Sahne Sanatları Bölümü Duysal (Ses) Sanatları Tasarımı Programı İstanbul/Türkiye Yildiz Technical University Faculty of Art and Design Department of Music and Performing Arts Audio Design Program Istanbul/Turkey ___ Pd-list@lists.iem.at mailing list UNSUBSCRIBE and account-management -> https://lists.puredata.info/listinfo/pd-list
