/*
 * savetextfont.c
 *
 * Saves and restores the currently loaded font, with auxilliary information
 * if available, on Linux.
 *
 * hpa - 19950930
 *
 * This file is in the public domain.
 *
 */

#ifdef __linux__

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <linux/kd.h>

#ifndef PIO_FONTX
/*
 * If we're compiling with old Linux include files, add the following
 * definitions -- from Linux 1.3.29
 */

#define GIO_FONTX       0x4B6B  /* get font using struct consolefontdesc */
#define PIO_FONTX       0x4B6C  /* set font using struct consolefontdesc */
struct consolefontdesc {
        unsigned short charcount;      /* characters in font (256 or 512) */
        unsigned short charheight;     /* scan lines per character (1-32) */
        char *chardata;                /* font data in expanded form */
};
#endif

static struct consolefontdesc font_info;
static char *font_data = NULL;
static int fontx;		/* Did we use GIO_FONTX? */
static struct unimapdesc unimap = { 0, NULL };

/*
 * save_textfont:
 *
 * Save the current text font and information; should be called prior
 * to entering graphics mode.  fd should contain a file descriptor pointing
 * to the console.  Return 0 on success, 1 on failure.
 *
 */

int save_textfont(int fd)
{
  if ( font_data )
    free(font_data);
  if ( unimap.entries )
    free(unimap.entries);

  font_info.charcount = 0;
  font_info.chardata = NULL;

  if ( ioctl(fd, GIO_FONTX, &font_info) == 0 )
    {
      /* If errno is ENOMEM we can use the font_info data to allocate
         the necessary size array */

      fontx = 1;

      font_info.chardata = font_data = malloc(32*font_info.charcount);
      if ( !font_data )
	return 1;
      
      if ( ioctl(fd, GIO_FONTX, &font_info) < 0 )
	return 1;
    }
  else
    {
      /* GIO_FONTX is apparently not available (pre-1.3.1 kernel).
	 Use older GIO_FONT ioctl() */

      fontx = 0;

      font_data = malloc(32*256);
      if ( !font_data )
	return 1;

      if ( ioctl(fd, GIO_FONT, font_data) < 0 )
	return 1;
    }

  /* Save Unicode map, if available. */

  unimap.entry_ct = 0;
  unimap.entries = NULL;

  if ( ioctl(fd, GIO_UNIMAP, &unimap) && errno == ENOMEM )
    {
      unimap.entries = malloc(unimap.entry_ct*sizeof(struct unipair));
      if ( !unimap.entries )
	{
	  unimap.entry_ct = 0;
	  return -1;
	}
      if ( ioctl(fd, GIO_UNIMAP, &unimap) < 0 )
	return -1;
    }

  return 0;
}

/*
 * restore_textfont:
 *
 * Restore the console text font.  Should be called after return from
 * graphics mode.  Same args/return as save_textfont.
 *
 */

int restore_textfont(int fd)
{
  struct unimapinit ui;

  if ( !font_data )
    return 1;

  if ( fontx )
    {
      if ( ioctl(fd, PIO_FONTX, &font_info) < 0 )
	return 1;
    }
  else
    {
      if ( ioctl(fd, PIO_FONT, font_data) < 0 )
	return 1;
    }

  if ( unimap.entry_ct )
    {
      ui.advised_hashsize = 0;
      ui.advised_hashstep = 0;
      ui.advised_hashlevel = 0;

      if ( ioctl(fd, PIO_UNIMAPCLR, &ui) < 0 )
        return -1;

      if ( ioctl(fd, PIO_UNIMAP, &unimap) < 0 )
        return -1;
    }

  return 0;
}

#else

/* These are meaningless on non-Linux OS's */

int save_textfont(int fd) { return 0; }
int restore_textfont(int fd) { return 0; }

#endif