Mercurial > pub > dyncall > bindings
comparison python/pydc/examples/callback.py @ 54:918dab7a6606
- added callback support (comes with some bigger refactoring)
- allow CPython's Py{CObject,Capsule} to be used as 'p'ointers
| author | Tassilo Philipp |
|---|---|
| date | Tue, 02 Feb 2021 20:42:02 +0100 |
| parents | |
| children | 16151547265e |
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| 53:6387d39ecce2 | 54:918dab7a6606 |
|---|---|
| 1 # callback of python function to qsort(3) some numbers - this is just a example | |
| 2 # using an existing libc function that uses a callback; it's not practical for | |
| 3 # real world use as it comes with a huge overhead: | |
| 4 # - sorting requires many calls of the comparison function | |
| 5 # - each such callback back into python comes with a lot of overhead | |
| 6 # - on top of that, for this example, 2 memcpy(3)s are needed to access the | |
| 7 # data to compare, further adding to the overhead | |
| 8 | |
| 9 from pydc import * | |
| 10 import sys | |
| 11 import platform | |
| 12 import struct | |
| 13 | |
| 14 if sys.platform == "win32": | |
| 15 libc = load("msvcrt") | |
| 16 elif sys.platform == "darwin": | |
| 17 libc = load("/usr/lib/libc.dylib") | |
| 18 elif "bsd" in sys.platform: | |
| 19 #libc = load("/usr/lib/libc.so") | |
| 20 libc = load("/lib/libc.so.7") | |
| 21 elif platform.architecture()[0] == "64bit": | |
| 22 libc = load("/lib64/libc.so.6") | |
| 23 else: | |
| 24 libc = load("/lib/libc.so.6") | |
| 25 | |
| 26 | |
| 27 | |
| 28 fp_qsort = find(libc,"qsort") # void qsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)); | |
| 29 fp_memcpy = find(libc,"memcpy") # void * memcpy(void *dst, const void *src, size_t len); | |
| 30 | |
| 31 | |
| 32 | |
| 33 nums = bytearray(struct.pack("i"*8, 12, 3, 5, 99, 3, -9, -9, 0)) | |
| 34 es = int(len(nums)/8) # element size | |
| 35 | |
| 36 | |
| 37 def compar(a, b): | |
| 38 ba = bytearray(es) | |
| 39 call(fp_memcpy,"ppi)p", ba, a, es) | |
| 40 a = struct.unpack("i", ba)[0] | |
| 41 call(fp_memcpy,"ppi)p", ba, b, es) | |
| 42 b = struct.unpack("i", ba)[0] | |
| 43 return a - b | |
| 44 | |
| 45 cb = new_callback("pp)i", compar) | |
| 46 | |
| 47 # -------- | |
| 48 | |
| 49 print(*struct.unpack("i"*8, nums)) | |
| 50 | |
| 51 print('... qsort ...') | |
| 52 call(fp_qsort,"piip)v", nums, 8, es, cb) | |
| 53 | |
| 54 print(*struct.unpack("i"*8, nums)) | |
| 55 | |
| 56 | |
| 57 free_callback(cb) | |
| 58 |