Binary data exchange

[RasikaSrinivasan]

friends

I have a pair of simple python programs as follows:

#!/usr/bin/python
# broadcast.py
import socket
from ctypes import *
import random

class PurgeData(Structure):
_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]

myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
addr = ('localhost',myPort)
#sock.sendto(data,addr)

presdata = PurgeData()
presdata.press = 0
presdata.ticks = 100

for msg in range(1,20):
presdata.press = presdata.press+1
presdata.ticks = presdata.ticks+1
presdata.volume = random.random()
sock.sendto(presdata,addr)

#--------------------

#!/usr/bin/python
# Receiver
import socket

from ctypes import *

class PurgeData(Structure):
_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]

myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
addr = ('localhost',myPort)
sock.bind(addr)
presdata=PurgeData()

while True:
data,addr = sock.recvfrom(1024)
memmove(addressof(presdata),data.strip(),len(data.strip()))
print presdata.press, presdata.ticks, presdata.volume

---------------------

When I tried to run this I get some bizarre results:


1 101 0.343009024858
2 102 0.36397305131
3 103 0.495895296335
4 104 0.372055351734
5 105 0.933839201927
6 106 0.931187808514
7 107 0.876732826233
8 108 0.298638045788
1828716544 -754974720 0.183644190431
1845493760 1660944384 0.186560109258
1862270976 1056964608 0.18631502986
1879048192 1728053248 0.186902835965
1895825408 2097152000 0.18658298254
14 114 0.407857120037
15 115 0.833854913712
16 116 0.00646247947589
17 117 0.297783941031
18 118 0.58082228899
19 119 0.61717569828

the received data for the messages 9 thru 13 are not as expected.

I wonder if anyone can see what I am doing wrong?

Appreciate any hints. thanks, srini

 

[RasikaSrinivasan]

BTW - My environment is:

H:\>python
Enthought Canopy Python 2.7.6 | 64-bit | (default, Apr 11 2014, 20:31:44) [MSC v
..1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.

 

[MRAB]

friends

I have a pair of simple python programs as follows:

#!/usr/bin/python
# broadcast.py
import socket
from ctypes import *
import random

class PurgeData(Structure):
_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]

myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
addr = ('localhost',myPort)
#sock.sendto(data,addr)

presdata = PurgeData()
presdata.press = 0
presdata.ticks = 100

for msg in range(1,20):
presdata.press = presdata.press+1
presdata.ticks = presdata.ticks+1
presdata.volume = random.random()
sock.sendto(presdata,addr)

#--------------------

#!/usr/bin/python
# Receiver
import socket

from ctypes import *

class PurgeData(Structure):
_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]

myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
addr = ('localhost',myPort)
sock.bind(addr)
presdata=PurgeData()

while True:
data,addr = sock.recvfrom(1024)
memmove(addressof(presdata),data.strip(),len(data.strip()))
print presdata.press, presdata.ticks, presdata.volume

---------------------

When I tried to run this I get some bizarre results:


1 101 0.343009024858
2 102 0.36397305131
3 103 0.495895296335
4 104 0.372055351734
5 105 0.933839201927
6 106 0.931187808514
7 107 0.876732826233
8 108 0.298638045788
1828716544 -754974720 0.183644190431
1845493760 1660944384 0.186560109258
1862270976 1056964608 0.18631502986
1879048192 1728053248 0.186902835965
1895825408 2097152000 0.18658298254
14 114 0.407857120037
15 115 0.833854913712
16 116 0.00646247947589
17 117 0.297783941031
18 118 0.58082228899
19 119 0.61717569828

the received data for the messages 9 thru 13 are not as expected.

I wonder if anyone can see what I am doing wrong?

Appreciate any hints. thanks, srini

I don't understand why you're using the .strip method. That's for
stripping whitespace from text, but you're not sending and receiving
text, you're sending and receiving binary data.

Personally, I'd use the struct module.

 

[RasikaSrinivasan]

Of course!!!! Cut and paste issue. Anyhow, i will look at the struct module. cheers, srini

friends

I have a pair of simple python programs as follows:


# broadcast.py

import socket

from ctypes import *

import random

class PurgeData(Structure):

_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]
myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)

addr = ('localhost',myPort)

#sock.sendto(data,addr)

presdata = PurgeData()

presdata.press = 0

presdata.ticks = 100

for msg in range(1,20):

presdata.press = presdata.press+1

presdata.ticks = presdata.ticks+1

presdata.volume = random.random()





# Receiver

import socket

from ctypes import *

class PurgeData(Structure):

_fields_ = [("press",c_int), ("ticks",c_int), ("volume",c_float)]
myPort = 10756

sock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)

addr = ('localhost',myPort)

sock.bind(addr)

presdata=PurgeData()

while True:

data,addr = sock.recvfrom(1024)

print presdata.press, presdata.ticks, presdata.volume



When I tried to run this I get some bizarre results:


1 101 0.343009024858

2 102 0.36397305131

3 103 0.495895296335

4 104 0.372055351734

5 105 0.933839201927

6 106 0.931187808514

7 107 0.876732826233

8 108 0.298638045788

1828716544 -754974720 0.183644190431

1845493760 1660944384 0.186560109258

1862270976 1056964608 0.18631502986

1879048192 1728053248 0.186902835965

1895825408 2097152000 0.18658298254

14 114 0.407857120037

15 115 0.833854913712

16 116 0.00646247947589

17 117 0.297783941031

18 118 0.58082228899

19 119 0.61717569828

the received data for the messages 9 thru 13 are not as expected.

I wonder if anyone can see what I am doing wrong?

Appreciate any hints. thanks, srini

I don't understand why you're using the .strip method. That's for

stripping whitespace from text, but you're not sending and receiving

text, you're sending and receiving binary data.



Personally, I'd use the struct module.

 

[Mark Lawrence]

Of course!!!! Cut and paste issue. Anyhow, i will look at the struct module. cheers, srini

Please let us know how you get on, please don't top post, and please
either use the mailing list
https://mail.python.org/mailman/listinfo/python-list or read and action
this https://wiki.python.org/moin/GoogleGroupsPython to prevent us
seeing double line spacing and single line paragraphs, thanks.