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how can i convert the ip address into decimal

Asked by mez kari on 2 Aug 2019
Latest activity Commented on by dpb
on 5 Aug 2019
Hello,
for exemple i have this address and i want to convert it in decimal how can I do this with matlab
192.192.192.2

  3 Comments

dpb
on 2 Aug 2019
What does "convert into decimal" mean to you? It is decimal as is...
Do you mean how do I parse out the 4 fields into numeric data?
ipFields = str2double(split('192.192.192.2', '.'))
i will explaine to you i have sensor connected into my pc via ethernet : i have in my project function wich return for me this number (3233857538) and when i ping this number it return me the ip i write on top so i think it's a number we get when we convert the ip i don't know.
if i put dec2hex(3233857538) it return exactly the same when i convert the ip in hex wich is C0C0C002
see this exemple in c++ :
void SetDeviceInterface(unsigned int nInterface, int nAdditional)
Setting of the number of an interface and transfer of an additional parameter. The additional parameter is used in order to indicate the baud rate of the serial interface. Therefore, the value has to be 115 200. In case of Ethernet interface, nInterface corresponds to the IP address in the so-called host byte order, wherein the 4 bits of the IP address of the sequence are still saved from the highest to the lowest byte. This can be easily achieved by means of a shift operation of the individual bytes of the IP address, as seen in the example for the address
192.168.1.2:
(192<<24) | (168<<16) | (1<<8) | 2 = 3232235778 = 0xC0A80102
but if you know to how to use this in matlab (192<<24......) explain to me or show me an example
thanks for response

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1 Answer

Answer by Joel Handy on 2 Aug 2019
Edited by Joel Handy on 2 Aug 2019

ipFields = uint8(str2double(split('192.192.192.2', '.')))';
typecast(fliplr(ipFields), 'uint32')
% Explanation
dec2hex(192)
dec2hex(2)
Each field of an Ip address is an 8 bit (1 byte) integer, which can be represented by 2 digits in hexadecimal. If you squish the four 8 bit fields together, you get a single 32 bit integer which can be represented by 8 hexadecimal digits.
192.192.192.2 => [192 192 192 2] => [0C 0C 0C 02] => 0C0C0C02 => 3233857538
The typecast is where you "squish" the individual bytes together.
The field reordering is necessary due to the order of bits and bytes in memory. Different systems store bits in different orders. Some systems store data most significant bit, MSB, first while other store data least significant bit first, LSB. Some systems put the most significant byte before the least significant byte, which is called big endian, while others do the revers which is called little endian. You need to be aware of how your system stores data in order to correctly order the bytes before you squish them together.

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I'm a little rusty on calling C code from Matlab as well as my C++. I know you need to use loadlibrary before calling calllib. I believe the call would look something like this:
loadlibrary(<dll file path>, <header file path>);
result = calllib(<dll name>, 's_SetFeature', int32(input1), uint32(input2), uint32(input3));
There are a lot of unknowns. the function you call out, s_SetFeature, doesnt appear in the code snippet you shared. There is a function SetFeature but it only takes two inputs not three.
#DEFINES are macros. anywhere int he code where you See TRIG_INTERNAL, its getting replaced with (0 << 25) at compile time. In this case (0 << 25) appears to be a bitshift operator. But its bitshifting 0 which doesnt really make sense to me since an unsigned integer 0 is still 0 wether you bitshift it or not.
Hopefully someone else can chime in with a better answer to your follow up. If this answers your original question though, I encourage you to accept the answer to help anyone with a similar question.
What i want to know is how to write (0<<25) in matlab
dpb
on 5 Aug 2019
"how to write (0<<25) in matlab"
0 is still 0
>> bitshift(0,25)
ans =
0
>>

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