AsciiCam/C/lib/nl_start.c

extern int main(int argc, char *argv[]);

__attribute__((naked)) void _start(void) {
  __asm__ volatile(
      "xor   %%rbp, %%rbp  \n"
      "pop   %%rdi          \n" /* rdi = argc                           */
      "mov   %%rsp, %%rsi   \n" /* rsi = argv                           */
      "and   $-16, %%rsp    \n" /* 16-byte align stack                  */
      "call  main           \n"
      "mov   %%rax, %%rdi   \n" /* exit code = return value of main()   */
      "mov   $231, %%rax    \n" /* SYS_exit_group                       */
      "syscall              \n" ::
          : "memory");
}