Python module to assemble snippets of code

asm.py

#!/usr/bin/env python
import os, tempfile, shutil, subprocess

class AsmException(Exception):
	pass

class BaseAsm(object):
	def __init__(self, source, addr = 0):
		self.source = source
		self._tmp = tempfile.mkdtemp() + os.sep
		self.addr = addr
		self.compile(source)

	def compile(self, source):
		self.sfile = self._tmp + "b.S"
		with open(self.sfile, "w") as fd:
			fd.write(self.HEADER + "\n")
			fd.write(source + "\n")
			fd.write(self.FOOTER + "\n")
		
		self.elffile = self._tmp + "b.elf"
		self.bfile = self._tmp + "b.b"
		self.nfile = self._tmp + "b.n"

		subprocess.check_call("%sgcc %s -Ttext=0x%x -o %s %s" % (self.PREFIX, self.CFLAGS, self.addr, self.elffile, self.sfile), shell=True)
		subprocess.check_call("%sobjcopy -j.text -O binary %s %s" % (self.PREFIX, self.elffile, self.bfile), shell=True)
		subprocess.check_call("%snm %s > %s" % (self.PREFIX, self.elffile, self.nfile), shell=True)

		with open(self.bfile, "rb") as fd:
			self.data = fd.read()

		with open(self.nfile) as fd:
			for line in fd:
				line = line.replace("\n", "")
				addr, type, name = line.split()
				addr = int(addr, 16)
				setattr(self, name, addr)
		self.start = self._start
		self.len = len(self.data)
		self.end = self.start + self.len

	def objdump(self):
		subprocess.check_call("%sobjdump -rd %s" % (self.PREFIX, self.elffile), shell=True)

	def __del__(self):
		if self._tmp:
			shutil.rmtree(self._tmp)
			self._tmp = None

class ARMAsm(BaseAsm):
	PREFIX = os.path.join("arm-none-eabi-")
	CFLAGS = "-mcpu=cortex-m3 -pipe -Wall -nostartfiles -nodefaultlibs"
	HEADER = """
	.text
	.arm
	.globl _start
_start:
	"""
	FOOTER = """
	.pool
	"""

class THUMBAsm(ARMAsm):
	HEADER = ARMAsm.HEADER.replace(".arm", ".thumb")
	CFLAGS = ARMAsm.CFLAGS + " -mthumb"

if __name__ == "__main__":
	code = """
	ldr r0, =0xDEADBEEF
	b test
	svc 1
test:
	b test
"""
	c = ARMAsm(code, 0x1234)
	c.objdump()
	assert c.start == 0x1234
	assert c.test == 0x1240