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README.md

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+# ShivyC [![Build Status](https://travis-ci.org/ShivamSarodia/ShivyC.svg?branch=master)](https://travis-ci.org/ShivamSarodia/ShivyC) [![Code Coverage](https://codecov.io/gh/ShivamSarodia/ShivyC/branch/master/graph/badge.svg)](https://codecov.io/gh/ShivamSarodia/ShivyC)
+
+### A hobby C compiler created in Python.
+
+![ShivyC demo GIF.](https://raw.githubusercontent.com/ShivamSarodia/ShivyC/master/demo.gif)
+
+---
+
+ShivyC is a hobby C compiler created in Python that supports a subset of the C11 standard and generates reasonably efficient binaries, including some optimizations. ShivyC also generates helpful compile-time error messages. x86-64 Linux is natively supported and a Dockerfile is provided for running on other platforms.
+
+This [implementation of a trie](tests/general_tests/trie/trie.c) is an example of what ShivyC can compile today. For a more comprehensive list of features, see the [feature test directory](tests/feature_tests).
+
+## Quickstart
+
+### x86-64 Linux
+ShivyC requires only Python 3 to compile C code. Assembling and linking are done using the GNU binutils and glibc, which you almost certainly already have installed.
+
+To install ShivyC:
+```
+pip3 install shivyc
+```
+To create, compile, and run an example program:
+```c
+$ vim hello.c
+$ cat hello.c
+
+#include <stdio.h>
+int main() {
+  printf("hello, world!\n");
+}
+
+$ shivyc hello.c
+$ ./out
+hello, world!
+```
+To run the tests:
+```
+git clone https://github.com/ShivamSarodia/ShivyC.git
+cd ShivyC
+python3 -m unittest discover
+```
+
+### Other Architectures
+For the convenience of those not running Linux, the [`docker/`](docker/) directory provides a Dockerfile that sets up an x86-64 Linux Ubuntu environment with everything necessary for ShivyC. To use this, run:
+```
+git clone https://github.com/ShivamSarodia/ShivyC.git
+cd ShivyC
+docker build -t shivyc docker/
+docker/shell
+```
+This will open up a shell in an environment with ShivyC installed and ready to use with
+```
+shivyc any_c_file.c           # to compile a file
+python3 -m unittest discover  # to run tests
+```
+The Docker ShivyC executable will update live with any changes made in your local ShivyC directory.
+
+## Implementation Overview
+### Preprocessor
+ShivyC today has a very limited preprocessor that parses out comments and expands `#include` directives. These features are implemented between [`lexer.py`](shivyc/lexer.py) and [`preproc.py`](shivyc/lexer.py).
+
+### Lexer
+The ShivyC lexer is implemented primarily in [`lexer.py`](shivyc/lexer.py). Additionally, [`tokens.py`](shivyc/tokens.py) contains definitions of the token classes used in the lexer and [`token_kinds.py`](shivyc/token_kinds.py) contains instances of recognized keyword and symbol tokens.
+
+### Parser
+The ShivyC parser uses recursive descent techniques for all parsing. It is implented in [`parser/*.py`](shivyc/parser/) and creates a parse tree of nodes defined in [`tree/nodes.py`](shivyc/tree/nodes.py) and [`tree/expr_nodes.py`](shivyc/tree/expr_nodes.py).
+
+### IL generation
+ShivyC traverses the parse tree to generate a flat custom IL (intermediate language). The commands for this IL are in [`il_cmds/*.py`](shivyc/il_cmds/) . Objects used for IL generation are in [`il_gen.py`](shivyc/il_gen.py) , but most of the IL generating code is in the `make_code` function of each tree node in [`tree/*.py`](shivyc/tree/).
+
+### ASM generation
+ShivyC sequentially reads the IL commands, converting each into Intel-format x86-64 assembly code. ShivyC performs register allocation using George and Appel’s iterated register coalescing algorithm (see References below). The general ASM generation functionality is in [`asm_gen.py`](shivyc/asm_gen.py) , but much of the ASM generating code is in the `make_asm` function of each IL command in [`il_cmds/*.py`](shivyc/il_cmds/).
+
+## Contributing
+ShivyC has so far been an entirely individual project, but pull requests are very welcome! Please add test(s) for all new functionality.
+
+## References
+- [ShivC](https://github.com/ShivamSarodia/ShivC) - ShivyC is a rewrite from scratch of my old C compiler, ShivC, with much more emphasis on feature completeness and code quality. See the ShivC README for more details.
+- C11 Specification - http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
+- x86_64 ABI - http://web.archive.org/web/20160801075139/http://www.x86-64.org/documentation/abi.pdf
+- Iterated Register Coalescing (George and Appel) - https://www.cs.purdue.edu/homes/hosking/502/george.pdf