[PD] Getting 32 bit floating point number from 4 sequential bytes

[cyrille henry]

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 <ardaeden at gmail.com <mailto:ardaeden at 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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