Custom C startup code (mainCRTStartup) implementation for GCC/MinGW.
Nocrt0 is a custom C startup code without any dependencies of the standard C runtime libraries. It is intended for building very small executable files under OS Windows(R). Nocrt0 was successfully tested with GCC/MinGW 7.2.0 and Pelles C 8.0. It is also possible that nocrt0 could be adapted for other C compilers, including Microsoft Visual C, as well, however, the source code requires some of C99 language features, so it cannot be compiled with msvc directly.
There are two modules: nocrt0w for GUI applications, and nocrt0c for
console applications. Simply add the correct source into your project and build
it without linking to the default C startup code (hint: for GCC you will need
nostdlib or nostartfiles option).
The process of building nocrt0 can also be controlled with the following DEFINEs:
-D_UNICODE
-DARGV={own | msvcrt | none}
_UNICODE builds "wide" version of the startup code (wmain or wWinMain).
ARGV is used for a console application (nocrt0c) only. It selects the type of
the underlying implementation of the standard command-line parser (argc/argv).
own (default) is the built-in implementation (note: envp is not supported and
is always set to NULL); msvcrt makes use of an external function __getmainargs()
(which is normally imported from msvcrt.dll); none is intended for applications
which do not need any command-line processing (int main(void)).
GCC note: nocrt0 includes the internal assembly (both x86 and x86-64) implementation
of __alloca function. That means you shouldn't link your application with libgcc.a.
If it's undesirable you have to patch the source code first.