extend readme (dev section), arm is now able to compile vmprof (tested on armv7l raspberry pi)

Author: planrich

README.md

@@ -27,6 +27,7 @@ Setting up development can be done using the following commands:
 	$ source vmprof3/bin/activate
 	$ python setup.py develop
 
+You need to install python development packages. In case of e.g. Debian or Ubuntu the package you need is `python3-dev` and `libunwind-dev`.
 Now it is time to write a test and implement your feature. If you want
 your changes to affect vmprof.com, head over to
 https://github.com/vmprof/vmprof-server and follow the setup instructions.

setup.py

@@ -2,6 +2,7 @@
 from distutils.command.build_py import build_py
 import os, sys
 import subprocess
+import platform
 
 IS_PYPY = '__pypy__' in sys.builtin_module_names
 
@@ -39,10 +40,15 @@ def run(self):
         extra_compile_args = ['-Wno-unused']
         extra_compile_args += ['-DVMPROF_LINUX=1']
         extra_compile_args += ['-DVMPROF_UNIX=1']
-        if sys.maxsize == 2**63-1:
-            libraries.append('unwind-x86_64')
+        if platform.machine().startswith("arm"):
+            libraries.append('unwind-arm')
+        elif platform.machine().startswith("x86"):
+            if sys.maxsize == 2**63-1:
+                libraries.append('unwind-x86_64')
+            else:
+                libraries.append('unwind-x86')
         else:
-            libraries.append('unwind-x86')
+            raise NotImplementedError
         extra_source_files += [
            'src/vmprof_mt.c',
            'src/vmprof_unix.c',

src/_vmprof.c

@@ -36,6 +36,8 @@ PY_EVAL_RETURN_T * vmprof_eval(PY_STACK_FRAME_T *f, int throwflag)
     register PY_STACK_FRAME_T * callee_saved asm("rbx");
 #elif defined(X86_32)
     register PY_STACK_FRAME_T * callee_saved asm("edi");
+#elif defined(__arm__)
+    register PY_STACK_FRAME_T * callee_saved asm("r4");
 #else
 #    error "platform not supported"
 #endif
@@ -45,6 +47,8 @@ PY_EVAL_RETURN_T * vmprof_eval(PY_STACK_FRAME_T *f, int throwflag)
         "movq %1, %0\t\n"
 #elif defined(X86_32)
         "mov %1, %0\t\n"
+#elif defined(__arm__)
+	"mov %1, %0\t\n"
 #else
 #    error "platform not supported"
 #endif