/* Copyright (C) 1992, 1993, 1994 artofcode LLC.  All rights reserved.
  
  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; either version 2 of the License, or (at your
  option) any later version.

  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.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/*$Id: gp_msdos.c,v 1.2.6.1.2.1 2003/01/17 00:49:02 giles Exp $ */
/* Common platform-specific routines for MS-DOS (any compiler) */
#include "stdio_.h"
#include "string_.h"		/* for strerror */
#include "dos_.h"
#include "gstypes.h"
#include "gsmemory.h"		/* for gp.h */
#include "gp.h"

/* ------ Miscellaneous ------ */

/* Get the string corresponding to an OS error number. */
/* This is compiler-, not OS-, specific, but it is ANSI-standard and */
/* all MS-DOS and MS Windows compilers support it. */
const char *
gp_strerror(int errnum)
{
    return strerror(errnum);
}

/* ------ Date and time ------ */

/* Read the current time (in seconds since Jan. 1, 1980) */
/* and fraction (in nanoseconds). */
void
gp_get_realtime(long *pdt)
{
    union REGS osdate, ostime;
    long idate;
    static const int mstart[12] =
    {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};

    osdate.h.ah = 0x2a;		/* get date */
    intdos(&osdate, &osdate);
#define da_year rshort.cx
#define da_mon h.dh
#define da_day h.dl
    ostime.h.ah = 0x2c;		/* get time */
    intdos(&ostime, &ostime);
#define ti_hour h.ch
#define ti_min h.cl
#define ti_sec h.dh
#define ti_hund h.dl
    idate = (long)osdate.da_year * 365 +
	(			/* intervening leap days */
	    ((osdate.da_year + 1979) / 4 - 1979 / 4) +
	    (1979 / 100 - (osdate.da_year + 1979) / 100) +
	    ((osdate.da_year + 1979) / 400 - 1979 / 400) +
	    mstart[osdate.da_mon - 1] +		/* month is 1-origin */
	    osdate.da_day - 1);	/* day of month is 1-origin */
    idate += (2 < osdate.da_mon
	      && (osdate.da_year % 4 == 0
		  && ((osdate.da_year + 1980) % 100 != 0
		      || (osdate.da_year + 1980) % 400 == 0)));
    pdt[0] =
	((idate * 24 + ostime.ti_hour) * 60 + ostime.ti_min) * 60 +
	ostime.ti_sec;
    pdt[1] = ostime.ti_hund * 10000000;
}

/* Read the current user CPU time (in seconds) */
/* and fraction (in nanoseconds).  */
void
gp_get_usertime(long *pdt)
{
    gp_get_realtime(pdt);	/* Use an approximation for now.  */
}

/* ------ Console management ------ */

/* Answer whether a given file is the console (input or output). */
/* This is not a standard gp procedure, */
/* but the MS Windows configuration needs it, */
/* and other MS-DOS configurations might need it someday. */
int
gp_file_is_console(FILE * f)
{
    union REGS regs;

#ifdef __DLL__
    if (f == NULL)
	return 1;
#else
    if (f == NULL)
	return 0;
#endif
    regs.h.ah = 0x44;		/* ioctl */
    regs.h.al = 0;		/* get device info */
    regs.rshort.bx = fileno(f);
    intdos(&regs, &regs);
    return ((regs.h.dl & 0x80) != 0 && (regs.h.dl & 3) != 0);
}

/* ------ Screen management ------ */

/* Get the environment variable that specifies the display to use. */
const char *
gp_getenv_display(void)
{
    return NULL;
}

/* ------ File names ------ */

/* Define the default scratch file name prefix. */
const char gp_scratch_file_name_prefix[] = "_temp_";

/* Define the name of the null output file. */
const char gp_null_file_name[] = "nul";

/* Define the name that designates the current directory. */
const char gp_current_directory_name[] = ".";