cosmopolitan/libc/calls/readv-serial.c

56 lines
2.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "ape/lib/pc.h"
#include "libc/calls/internal.h"
#include "libc/nexgen32e/uart.internal.h"
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 readv$serial(struct Fd *fd, const struct iovec *iov, int iovlen) {
size_t i, j, got = 0;
if ((i = GetFirstIov(iov, iovlen)) != -1) {
while (!IsDataAvailable(fd)) asm("pause");
i = 0;
j = 0;
do {
++got;
((char *)iov[i].iov_base)[j] = inb(fd->handle);
if (++j == iov[i].iov_len) {
j = 0;
if (++i == iovlen) {
break;
}
}
} while (IsDataAvailable(fd));
}
return got;
}