/*** thinlib (c) 2000 Matthew Conte (matt@conte.com)****** This program is free software; you can redistribute it and/or** modify it under the terms of version 2 of the GNU Library General ** Public License as published by the Free Software Foundation.**** 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 ** Library General Public License for more details.  To obtain a ** copy of the GNU Library General Public License, write to the Free ** Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.**** Any permitted reproduction of these routines, in whole or in part,** must bear this legend.****** tl_timer.c**** DOS timer routines** $Id: tl_timer.c,v 1.4 2001/03/12 06:06:56 matt Exp $*/#include <go32.h>#include <pc.h>#include <dpmi.h>#include "tl_types.h"#include "tl_djgpp.h"#include "tl_timer.h"#define  TIMER_INT         0x08#define  TIMER_TICKS       1193182Lstatic _go32_dpmi_seginfo old_handler, new_handler;static struct{   timerhandler_t handler;   int interval, frac, current;   bool initialized;} timer;/* Reprogram the PIT timer to fire at a specified value */void thin_timer_setrate(int hertz){   int time;   if (0 == hertz)      time = 0;   else      time = TIMER_TICKS / (long) hertz;   timer.interval = time;   timer.frac = time & 0xFFFF;   timer.current = 0;   outportb(0x43, 0x34);   outportb(0x40, timer.frac & 0xFF);   outportb(0x40, timer.frac >> 8);}static void _timer_int_handler(void){   outportb(0x20, 0x20);      timer.current += timer.frac;   if (timer.current >= timer.interval)   {      timer.current -= timer.interval;      timer.handler();   }}THIN_LOCKED_STATIC_FUNC(_timer_int_handler);/* Lock code, data, and chain an interrupt handler */int thin_timer_init(int hertz, timerhandler_t func_ptr){   THIN_LOCK_FUNC(_timer_int_handler);   THIN_LOCK_VAR(timer);   timer.handler = func_ptr;   /* Save the old vector, stuff the new one in there */   _go32_dpmi_get_protected_mode_interrupt_vector(TIMER_INT, &old_handler);   new_handler.pm_offset = (int) _timer_int_handler;   new_handler.pm_selector = _go32_my_cs();   _go32_dpmi_chain_protected_mode_interrupt_vector(TIMER_INT, &new_handler);   /* Set PIC to fire at desired refresh rate */   thin_timer_setrate(hertz);   timer.initialized = true;   return 0;}/* Remove the timer handler */void thin_timer_shutdown(void){   if (false == timer.initialized)      return;   /* Restore previous timer setting */   thin_timer_setrate(0);   /* Remove the interrupt handler */   _go32_dpmi_set_protected_mode_interrupt_vector(TIMER_INT, &old_handler);   timer.initialized = false;}/*** $Log: tl_timer.c,v $** Revision 1.4  2001/03/12 06:06:56  matt** better keyboard driver, support for bit depths other than 8bpp**** Revision 1.3  2000/12/16 21:18:11  matt** thinlib cleanups**** Revision 1.2  2000/12/13 13:58:20  matt** cosmetic fixes**** Revision 1.1  2000/11/05 06:29:03  matt** initial revision***/