passing a pointer value to a C function from python

Question

I have a C function which takes a int and returns by filling up the value in b

typedef   uint8_t State;
#define   STATE_POWERDOWN               ((State) 0x00) 
#define   STATE_SLEEP                   ((State) 0x10) 


int Val_GetStatus(int a , State *b)

This function alongwith others has been exported from a C DLL.

I call this function from python. While I am able to connect with the DLL I don't understand how to pass a variable to this function in python ?

def Acme_getDeviceStatus(self,DeviceStatus):
    # b 
    self.device.Val_GetStatus(0,b)  # how to pass and get value in b
    # DeviceStatus = b
    # return DeviceStatus somehow

How is State defined in C?

wenzul
– wenzul

2014-10-14 14:54:58 +00:00
Commented Oct 14, 2014 at 14:54 — wenzul
– wenzul, Commented Oct 14, 2014 at 14:54
@wenzul updated with definition of State

user974168
– user974168

2014-10-14 14:59:25 +00:00
Commented Oct 14, 2014 at 14:59 — user974168
– user974168, Commented Oct 14, 2014 at 14:59
Maybe this could help: docs.python.org/2/library/…

Vorac
– Vorac

2014-10-14 15:01:16 +00:00
Commented Oct 14, 2014 at 15:01 — Vorac
– Vorac, Commented Oct 14, 2014 at 15:01

wenzul · Accepted Answer · 2014-10-14 15:09:53Z

6

You can use for example ctypes or swig to call C functions in Python.

from ctypes import *

Val_GetStatus= CDLL('x').Val_GetStatus
Val_GetStatus.argtypes = [c_int,POINTER(c_unit8)]
Val_GetStatus.restype = c_int

deviceStatus = ctypes.c_uint8()

print Val_GetStatus(0, byref(deviceStatus))
print deviceStatus.value

Swig will generate kind of interface for you, so you don't have to do it manually.

answered Oct 14, 2014 at 15:09

wenzul

4,0782 gold badges24 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

passing a pointer value to a C function from python

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related