#include "uart.h"

#include <sys/stat.h>
#include <sys/times.h>
#include <sys/types.h>

#include <errno.h>
#undef errno
extern int errno;

// defined in crt0.S
void _exit(int c);

int _close(int file) { return -1; }

char *__env[1] = {0};
char **environ = __env;

int _execve(char *name, char **argv, char **env) {
  errno = ENOMEM;
  return -1;
}

int _fork(void) {
  errno = EAGAIN;
  return -1;
}

int _fstat(int file, struct stat *st) {
  st->st_mode = S_IFCHR;
  return 0;
}

int _getpid(void) { return 1; }
int _isatty(int file) { return 1; }

int _link(char *old, char *new) {
  errno = EMLINK;
  return -1;
}

int _lseek(int file, int ptr, int dir) { return 0; }

int _open(const char *name, int flags, int mode) { return -1; }

int _read(int file, char *buf, int len) {
  while (!uart_rx_ready())
    ;

  int i;
  for (i = 0; i < len; i++) {
    if (!uart_rx_ready()) {
      break;
    }
    buf[i] = uart_getc_nonblocking();
  }
  return i;
}

void *_sbrk(int incr) {
  extern void _heap_start;
  extern void *_heap_end;
  void *prev_heap_end = _heap_end;

  void *stack_ptr;
  __asm__ volatile("mv %0, sp" : "=r"(stack_ptr));
  if (_heap_end + incr > stack_ptr) {
    uart_puts("Heap and stack collision\n");
    _exit(1);
  }

  _heap_end += incr;
  return prev_heap_end;
}

int _stat(const char *__restrict file, struct stat *__restrict st) {
  st->st_mode = S_IFCHR;
  return 0;
}

clock_t _times(struct tms *buf) { return (clock_t)-1; }

int _unlink(char *name) {
  errno = ENOENT;
  return -1;
}

int _wait(int *status) {
  errno = ECHILD;
  return -1;
}

int _write(int file, char *buf, int len) {
  for (int i = 0; i < len; i++) {
    uart_putc(buf[i]);
  }
  return len;
}

int _kill(int pid, int sig) {
  errno = EINVAL;
  return -1;
}