com32/lib/sys/serial_write.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2004 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * serial_write.c
  30  *
  31  * Raw writing to the serial port; no \n -> \r\n translation
  32  */
  33
  34 #include <errno.h>
  35 #include <string.h>
  36 #include <com32.h>
  37 #include <minmax.h>
  38 #include <syslinux/config.h>
  39 #include "file.h"
  40
  41 ssize_t __serial_write(struct file_info *fp, const void *buf, size_t count)
  42 {
  43   com32sys_t ireg;
  44   const char *bufp = buf;
  45   size_t n = 0;
  46
  47   (void)fp;
  48
  49   if (!syslinux_serial_console_info()->iobase)
  50     return count;               /* Nothing to do */
  51
  52   memset(&ireg, 0, sizeof ireg);
  53   ireg.eax.b[1] = 0x04;
  54
  55   while ( count-- ) {
  56     ireg.edx.b[0] = *bufp++;
  57     __intcall(0x21, &ireg, NULL);
  58     n++;
  59   }
  60
  61   return n;
  62 }
  63
  64 const struct output_dev dev_serial_w = {
  65   .dev_magic  = __DEV_MAGIC,
  66   .flags      = __DEV_TTY | __DEV_OUTPUT,
  67   .fileflags  = O_WRONLY | O_CREAT | O_TRUNC | O_APPEND,
  68   .write      = __serial_write,
  69   .close      = NULL,
  70   .open       = NULL,
  71 };