cosmopolitan/libc/stdio/serialstdio.c

57 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 │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "ape/lib/pc.h"
#include "libc/nexgen32e/uart.h"
#include "libc/stdio/internal.h"
#include "libc/stdio/stdio.h"
static void fin(FILE *f) {
f->buf[f->end] = inb(0x3F8);
f->end = (f->end + 1) & (f->size - 1);
}
static void fout(FILE *f) {
outb(0x3F8, f->buf[f->beg]);
f->beg = (f->beg + 1) & (f->size - 1);
}
static int serialstdio(FILE *f, unsigned char status, void action(FILE *)) {
int block = 1;
unsigned tally = 0;
while (f->end != f->beg) {
if (!(inb(0x3F8 + UART_LSR) & status)) {
if (!block) break;
asm("pause");
} else {
action(f);
tally++;
}
}
return (int)tally;
}
int fsreadbuf(FILE *f) {
return serialstdio(f, UART_TTYDA, fin);
}
int fswritebuf(FILE *f) {
return serialstdio(f, UART_TTYTXR, fout);
}