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# Demonstrate some functions from the standard C library.
from ctypes import cdll, POINTER, CFUNCTYPE
import os, sys
from ctypes import c_char_p, c_double, c_char, sizeof
def c_string(init, size=None):
"""c_string(aString) -> character array
c_string(anInteger) -> character array
c_string(aString, anInteger) -> character array
"""
if isinstance(init, str):
if size is None:
size = len(init)+1
buftype = c_char * size
buf = buftype()
buf.value = init
return buf
elif isinstance(init, int):
buftype = c_char * init
buf = buftype()
return buf
raise TypeError, init
if os.name == "nt":
libc = cdll.msvcrt
printf = libc.printf
sscanf = libc.sscanf
snprintf = libc._snprintf
libmath = cdll.msvcrt
msvcrt = cdll.msvcrt
elif os.name == "posix":
if sys.platform == "darwin":
libc = cdll.LoadLibrary("/usr/lib/libc.dylib")
libmath = cdll.LoadLibrary("/usr/lib/libm.dylib")
elif sys.platform == "cygwin":
libmath = libc = cdll.LoadLibrary("/bin/cygwin1.dll")
else:
libc = cdll.LoadLibrary("/lib/libc.so.6")
libmath = cdll.LoadLibrary("/lib/libm.so.6")
printf = libc.printf
sscanf = libc.sscanf
snprintf = libc.snprintf
from ctypes import Structure, c_int, c_float, byref
def test_printf():
result = printf("%s%s %d 0x%x %f %d\n",
"Hello, ",
## u"World!",
"World!",
c_int(100),
c_int(100),
c_double(3.14159265),
100)
print "printf returned %d\n" % result
def test_time():
t = c_int()
result = libc.time(byref(t))
print "time since epoch in seconds:", result, t.value
def test_sscanf():
t1 = c_int(3)
t2 = c_float(32)
f = c_double()
result = sscanf("1234 Hello, 5678 World 3.14159265",
"%d Hello, %f World %lf %lf",
byref(t1),
byref(t2),
byref(f))
print "sscanf found %d fields:" % result,
print t1.value, t2.value, f.value
def test_snprintf():
buf = c_string("\000"*32)
print snprintf(buf, sizeof(buf), "Hello, world")
print "value: %r" % buf.value
def test_strtok():
strtok = libc.strtok
strtok.restype = c_char_p
delim = " "
t = c_string("Hi, how are you?")
s = t # we must hold a ref to the original string
while 1:
r = strtok(s, delim)
if not r:
break
s = 0
print "\t", r
print
def test_sqrt():
sqrt = libmath.sqrt
sqrt.restype = c_double
print sqrt(c_double(2))
# Other examples:
#
# sqrt: returns double
# div: returns a structure containig two ints
# ldiv: returns a structure containing two longs
# _findfirst,
# _findfirst64, returns __int64
# fopen - returns FILE *
# localtime, gmtime, ... - return struct tm *
def test_qsort():
import array, random
## class CMPFUNC(CFuncPtr):
## _argtypes_ = c_int, c_int
## _flags_ = FUNCFLAG_CDECL
CMPFUNC = CFUNCTYPE(c_int, c_int, c_int)
def compare(a, b):
ad = c_int.from_address(a)
bd = c_int.from_address(b)
return cmp(ad.value, bd.value)
data = array.array("i", range(5))
random.shuffle(data)
print "BEFORE qsort", data
libc.qsort(data.buffer_info()[0],
len(data),
4,
CMPFUNC(compare))
print "AFTER qsort", data
print
def test_qsort_1():
from _ctypes import Array
import random
class IntArray10(Array):
_type_ = c_int
_length_ = 10
l = range(10)
random.shuffle(l)
ia10 = IntArray10(*l)
print "BEFORE sorting:",
for item in ia10:
print item,
print
# It would be even nicer to define the callback so that
# it auto-converts the pointer into the value,
# then we could use callback(cmp, ...)
def compare(a, b):
ad = c_int.from_address(a)
bd = c_int.from_address(b)
return cmp(ad.value, bd.value)
## class CMPFUNC(CFuncPtr):
## _argtypes_ = c_int, c_int
## _flags_ = FUNCFLAG_CDECL
CMPFUNC = CFUNCTYPE(c_int, c_int, c_int)
libc.qsort(ia10,
len(ia10),
4,
CMPFUNC(compare))
print "AFTER sorting:",
for item in ia10:
print item,
print
print
def test_qsort_2():
import random
IntArray10 = c_int * 10
ia10 = IntArray10()
for i in range(10):
num = random.choice(range(100))
ia10[i] = c_int(num)
print "BEFORE sorting:",
for item in ia10:
print item,
print
# It would be even nicer to define the callback so that
# it auto-converts the pointer into the value,
# then we could use callback(cmp, ...)
def compare(a, b):
ad = c_int.from_address(a)
bd = c_int.from_address(b)
return cmp(ad.value, bd.value)
## class CMPFUNC(CFuncPtr):
## _argtypes_ = c_int, c_int
## _flags_ = FUNCFLAG_CDECL
CMPFUNC = CFUNCTYPE(c_int, c_int, c_int)
libc.qsort(ia10,
len(ia10),
4,
CMPFUNC(compare))
print "AFTER sorting:",
for item in ia10:
print item,
print
print
def test_qsort_5():
# demonstrates callback functions specified by using types in the _types_ list
import random
IntArray10 = c_int * 10
ia10 = IntArray10()
for i in range(10):
num = random.choice(range(100))
ia10[i] = num
print "BEFORE sorting:",
for item in ia10:
print item,
print
def compare(a, b):
"the callback now receives pointers to c_int:"
return cmp(a.contents.value, b.contents.value)
## class CMPFUNC(CFuncPtr):
## _argtypes_ = POINTER(c_int), POINTER(c_int)
## _flags_ = FUNCFLAG_CDECL
CMPFUNC = CFUNCTYPE(c_int, POINTER(c_int), POINTER(c_int))
libc.qsort(ia10,
len(ia10),
4,
CMPFUNC(compare))
print "AFTER sorting:",
for item in ia10:
print item,
print
print
if __name__ == '__main__':
test_printf()
test_time()
test_sscanf()
test_snprintf()
test_strtok()
test_sqrt()
test_qsort()
test_qsort_1()
test_qsort_2()
test_qsort_5()
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