hello.c

// $ cc -nostartfiles -o hello.exe hello.c
// $ ./hello world
// Ref: https://github.com/skeeto/w64devkit/discussions/340
// This is free and unencumbered software released into the public domain.
#include <stdint.h>
#include <uchar.h>

#define nil ((uintptr_t)0)
typedef uintptr_t Syscall(...);

typedef struct {
    Syscall *ExitProcess;
    Syscall *GetCommandLineW;
    Syscall *GetProcAddress;
    Syscall *GetStdHandle;
    Syscall *LoadLibraryA;
    Syscall *WriteConsoleW;
} Kernel32;

typedef struct {
    Syscall *CommandLineToArgvW;
} Shell32;

static Kernel32 new_kernel32()
{
    Syscall LoadLibraryA, GetProcAddress;  // bootstrap
    uintptr_t h = LoadLibraryA("kernel32");
    return (Kernel32){
        .ExitProcess     = (Syscall *)GetProcAddress(h, "ExitProcess"),
        .GetCommandLineW = (Syscall *)GetProcAddress(h, "GetCommandLineW"),
        .GetProcAddress  = (Syscall *)GetProcAddress(h, "GetProcAddress"),
        .GetStdHandle    = (Syscall *)GetProcAddress(h, "GetStdHandle"),
        .LoadLibraryA    = (Syscall *)GetProcAddress(h, "LoadLibraryA"),
        .WriteConsoleW   = (Syscall *)GetProcAddress(h, "WriteConsoleW"),
    };
}

static Shell32 new_shell32(Kernel32 kernel32)
{
    uintptr_t h = kernel32.LoadLibraryA("shell32");
    return (Shell32){
        .CommandLineToArgvW =
            (Syscall *)kernel32.GetProcAddress(h, "CommandLineToArgvW"),
    };
}

static ptrdiff_t char16len(char16_t *s)
{
    ptrdiff_t len = 0;
    for (; s[len]; len++) {}
    return len;
}

void mainCRTStartup()
{
    Kernel32 kernel32 = new_kernel32();
    Shell32  shell32  = new_shell32(kernel32);
    char16_t  *cmd  = (char16_t *)kernel32.GetCommandLineW();
    int        argc = {};
    char16_t **argv = (char16_t **)shell32.CommandLineToArgvW(cmd, &argc);
    uintptr_t  out  = kernel32.GetStdHandle(-11);
    for (int i = 1; i < argc; i++) {
        kernel32.WriteConsoleW(out, u"hello, ", 7, nil, nil);
        kernel32.WriteConsoleW(out, argv[i], char16len(argv[i]), nil, nil);
        kernel32.WriteConsoleW(out, u"\n", 1, nil, nil);
    }
    kernel32.ExitProcess(0);
}