#include <stdint.h>
#if defined(__x86_64__)

void exit(int8_t status) {
  asm volatile(
    "syscall"
    :
    : "a"(60), "D"(status)
    :
    );
}

intptr_t write(int32_t fd, const void* buf, intptr_t size) {
  intptr_t n_written = 0;
  asm volatile (
      "syscall\n"
      "movq %0, %%rax\n"
      : "=r"(n_written)
      : "a"(1), "D"(fd), "S"(buf), "d"(size)  // RDI, RSI, RDX are used in x86-64 for write args
      : "rcx", "r11", "memory"
  );
  return n_written;
}

uint32_t fork() {
  uint64_t rtn;
  asm volatile(
    "syscall\n"         // syscall
    "movq %0, %%rax\n"    // save return value
    : "=r"(rtn)
    : "a"(57)
    :
  );
  return (uint32_t)rtn;
}
#endif /* ifdef __x86_64__ */