ffi.py

import mmap
from cffi import FFI

"""
add.c
double add(double a, double b) {
  return a+b
}
~$ gcc -O3 -c add.c
~$ objdump -d add.o

add.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <add>:
   0:	f2 0f 58 c1          	addsd  %xmm1,%xmm0
   4:	c3                   	retq 
"""

# put binary code in buffer
code = b"\xf2\x0f\x58\xc1\xc3"
buf = mmap.mmap(-1, len(code), mmap.MAP_PRIVATE, mmap.PROT_READ | mmap.PROT_WRITE | mmap.PROT_EXEC)

# make ffi
ffi = FFI()
ffi.cdef("typedef double (*fn)(double, double);")

# get pointer to the code
fptr = ffi.cast("fn", ffi.from_buffer(buf))

# execute the code
print(fptr(4,4))