diff options
Diffstat (limited to 'README.html')
-rw-r--r-- | README.html | 65 |
1 files changed, 64 insertions, 1 deletions
diff --git a/README.html b/README.html index fe1fd75..e34ab71 100644 --- a/README.html +++ b/README.html @@ -28,4 +28,67 @@ it is nearly as fast in theory.</p> <p><code>tests</code> has some test programs written in <code>toc</code>.</p> -<p>To compile the compiler on a Unix-y system, use</p> +<p>To compile the compiler on a Unix-y system, just run <code>build.sh</code>. You can supply a compiler by running <code>CC=tcc build.sh</code>, or built it in release mode with <code>./build.sh release</code> (which will help speed up compiling large programs). </p> + +<p>On other systems, you can just compile main.c with a C compiler. toc uses several C99 and a couple of C11 features, so it might not work on all compilers. But it does compile on quite a few, including <code>clang</code>, <code>gcc</code>, and <code>tcc</code>. It can also be compiled as if it were C++, but it does break the standard in a few places*. So, MSVC can also compile it. The <em>outputted</em> code should be C99-compliant.</p> + +<hr /> + +<h3><code>toc</code> Source Code</h3> + +<p><code>toc</code> is written in C, for speed and portability. It has no dependencies, other than the C runtime library.</p> + +<h4>Build system</h4> + +<p><code>toc</code> is set up as a unity build, meaning that there is only one translation unit. So, <code>main.c</code> <code>#include</code>s <code>toc.c</code>, which <code>#include</code>s all of <code>toc</code>'s files. This improves (from scratch) compilation speeds, since you don't have to include headers a bunch of times for each translation unit. This is more of a problem in C++, where, for example, doing <code>#include <map></code> ends up turning into 25,000 lines after preprocessing. All of toc's source code, which includes most of the C standard library, at the time of this writing (Dec 2019) is only 22,000 lines after preprocessing; imagine including all of that once for each translation unit which includes <code>map</code>. It also obviates the need for fancy build systems like CMake.</p> + +<h4>New features</h4> + +<p>Here are all the C99 features which <code>toc</code> depends on (I might have forgotten some...):</p> + +<ul> +<li>Declare anywhere</li> +<li><code>stdint.h</code></li> +<li>Non-constant struct literal initializers (e.g. <code>int x[2] = {y, z};</code>)</li> +<li>Variadic macros and <code>__VA_ARGS__</code></li> +<li>Flexible array members</li> +</ul> + +<p>The last three of those could all be removed fairly easily.</p> + +<p>And here are all of its C11 features:</p> + +<ul> +<li>Anonymous structures/unions</li> +<li><code>max_align_t</code> and <code>alignof</code> - It can still compile without these but it won't technically be standard-compliant</li> +</ul> + +<h4>More</h4> + +<p>See <code>main.c</code> for a bit more information.</p> + +<hr /> + +<p>* for those curious, it has to do with <code>goto</code>. In C, this program:</p> + +<pre><code> +int main() { + goto label; + int x = 5; + label: + return 0; +} +</code></pre> + +<p>Is completely fine. <code>x</code> will hold an unspecified value after the jump (but it isn't used so it doesn't really matter). Apparently, in C++, this is an ill-formed program. This is a bit ridiculous since</p> + +<pre><code> +int main() { + goto label; + int x; x = 5; + label: + return 0; +} +</code></pre> + +<p>is fine. So that's an interesting little "fun fact": <code>int x = 5;</code> isn't always the same as <code>int x; x = 5;</code> in C++.</p> |