/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-â
âvi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :viâ
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â Copyright 2020 Justine Alexandra Roberts Tunney                              â
â                                                                              â
â Permission to use, copy, modify, and/or distribute this software for         â
â any purpose with or without fee is hereby granted, provided that the         â
â above copyright notice and this permission notice appear in all copies.      â
â                                                                              â
â THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                â
â WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                â
â WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             â
â AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         â
â DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        â
â PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               â
â TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             â
â PERFORMANCE OF THIS SOFTWARE.                                                â
ââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ*/
#include "libc/calls/struct/fd.internal.h"
#include "libc/calls/struct/iovec.internal.h"
#include "libc/nexgen32e/uart.internal.h"
#include "libc/runtime/pc.internal.h"
#ifdef __x86_64__

static bool IsDataAvailable(struct Fd *fd) {
  return inb(fd->handle + UART_LSR) & UART_TTYDA;
}

static int GetFirstIov(struct iovec *iov, int iovlen) {
  int i;
  for (i = 0; i < iovlen; ++i) {
    if (iov[i].iov_len) {
      return i;
    }
  }
  return -1;
}

ssize_t sys_readv_serial(struct Fd *fd, const struct iovec *iov, int iovlen) {
  size_t i;
  if ((i = GetFirstIov(iov, iovlen)) != -1) {
    while (!IsDataAvailable(fd)) {
      __builtin_ia32_pause();
    }
    ((char *)iov[i].iov_base)[0] = inb(fd->handle);
    return 1;
  } else {
    return 0;
  }
}

#endif
