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+<!--
+SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
+
+SPDX-License-Identifier: MIT
+-->
+
+MicroPython cross compiler
+==========================
+
+This directory contains the MicroPython cross compiler, which runs under any
+Unix-like system and compiles .py scripts into .mpy files.
+
+Build it as usual:
+
+    $ make
+
+The compiler is called `mpy-cross`.  Invoke it as:
+
+    $ ./mpy-cross foo.py
+
+This will create a file foo.mpy which can then be copied to a place accessible
+by the target MicroPython runtime (eg onto a pyboard's filesystem), and then
+imported like any other Python module using `import foo`.
+
+Different target runtimes may require a different format of the compiled
+bytecode, and such options can be passed to the cross compiler.
+
+If the Python code contains `@native` or `@viper` annotations, then you must
+specify `-march` to match the target architecture.
+
+Run `./mpy-cross -h` to get a full list of options.
+
+The optimisation level is 0 by default. Optimisation levels are detailed in
+https://docs.micropython.org/en/latest/library/micropython.html#micropython.opt_level