src/glut/dos/PC_HW/pc_timer.c

   1 /*
   2  * PC/HW routine collection v1.0 for DOS/DJGPP
   3  *
   4  *  Copyright (C) 2002 - Borca Daniel
   5  *  Email : dborca@yahoo.com
   6  *  Web   : http://www.geocities.com/dborca
   7  */
   8
   9
  10 #include <pc.h>
  11
  12 #include "pc_hw.h"
  13
  14 #define TIMER_IRQ 0
  15
  16 #define MAX_TIMERS 8
  17
  18 #define PIT_FREQ 0x1234DD
  19
  20 #define unvolatile(__v, __t) __extension__ ({union { volatile __t __cp; __t __p; } __q; __q.__cp = __v; __q.__p;})
  21
  22 static int timer_installed;
  23
  24 typedef struct {
  25         volatile unsigned int counter, clock_ticks, freq;
  26         volatile PFUNC func;
  27         volatile void *parm;
  28 } TIMER;
  29
  30 TIMER timer_main, timer_func[MAX_TIMERS];
  31
  32 static int timer ()
  33 {
  34  int i;
  35
  36  for (i=0;i<MAX_TIMERS;i++) {
  37      TIMER *t = &timer_func[i];
  38      if (t->func) {
  39         t->clock_ticks += t->counter;
  40         if (t->clock_ticks>=timer_main.counter) {
  41            t->clock_ticks -= timer_main.counter;
  42            t->func(unvolatile(t->parm, void *));
  43         }
  44      }
  45  }
  46
  47  timer_main.clock_ticks += timer_main.counter;
  48  if (timer_main.clock_ticks>=0x10000) {
  49     timer_main.clock_ticks -= 0x10000;
  50     return 1;
  51  } else {
  52     outportb(0x20, 0x20);
  53     return 0;
  54  }
  55 } ENDOFUNC(timer)
  56
  57 void pc_remove_timer (void)
  58 {
  59  if (timer_installed) {
  60     timer_installed = FALSE;
  61     pc_clexit(pc_remove_timer);
  62
  63     DISABLE();
  64     outportb(0x43, 0x34);
  65     outportb(0x40, 0);
  66     outportb(0x40, 0);
  67     ENABLE();
  68
  69     pc_remove_irq(TIMER_IRQ);
  70  }
  71 }
  72
  73 static int install_timer (void)
  74 {
  75  if (timer_installed||pc_install_irq(TIMER_IRQ, timer)) {
  76     return -1;
  77  } else {
  78     LOCKDATA(timer_func);
  79     LOCKDATA(timer_main);
  80     LOCKFUNC(timer);
  81
  82     timer_main.counter = 0x10000;
  83
  84     DISABLE();
  85     outportb(0x43, 0x34);
  86     outportb(0x40, 0);
  87     outportb(0x40, 0);
  88     timer_main.clock_ticks = 0;
  89     ENABLE();
  90
  91     pc_atexit(pc_remove_timer);
  92     timer_installed = TRUE;
  93     return 0;
  94  }
  95 }
  96
  97 static TIMER *find_slot (PFUNC func)
  98 {
  99  int i;
 100
 101  for (i=0;i<MAX_TIMERS;i++) {
 102      if (timer_func[i].func==func) {
 103         return &timer_func[i];
 104      }
 105  }
 106  for (i=0;i<MAX_TIMERS;i++) {
 107      if (!timer_func[i].func) {
 108         return &timer_func[i];
 109      }
 110  }
 111
 112  return NULL;
 113 }
 114
 115 int pc_install_int (PFUNC func, void *parm, unsigned int freq)
 116 {
 117  int i;
 118  TIMER *t;
 119
 120  if (!timer_installed) {
 121     if (install_timer()) {
 122        return -1;
 123     }
 124  }
 125
 126  if ((t=find_slot(func))!=NULL) {
 127     unsigned int new_counter = PIT_FREQ / freq;
 128
 129     DISABLE();
 130
 131     t->func = func;
 132     t->parm = parm;
 133     t->freq = freq;
 134     t->clock_ticks = 0;
 135
 136     if (new_counter < timer_main.counter) {
 137        for (i=0;i<MAX_TIMERS;i++) {
 138            if (timer_func[i].func) {
 139               timer_func[i].counter = new_counter * timer_func[i].freq / freq;
 140            }
 141        }
 142        outportb(0x43, 0x34);
 143        outportb(0x40, (unsigned char)new_counter);
 144        outportb(0x40, (unsigned char)(new_counter>>8));
 145        timer_main.clock_ticks = 0;
 146        timer_main.counter = new_counter;
 147        timer_main.freq = freq;
 148     } else {
 149        t->counter = PIT_FREQ * freq / (timer_main.freq * timer_main.freq);
 150     }
 151
 152     ENABLE();
 153
 154     return 0;
 155  }
 156
 157  return -1;
 158 }