git.mutantstargoat.com Git - cdmenu/blob - menu/src/dos/timer.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <assert.h>
   4 #include <conio.h>
   5 #include <dos.h>
   6
   7 #ifdef __WATCOMC__
   8 #include <i86.h>
   9 #endif
  10
  11 #ifdef __DJGPP__
  12 #include <dpmi.h>
  13 #include <go32.h>
  14 #include <pc.h>
  15 #endif
  16
  17 #include "pit8254.h"
  18 #include "sizeint.h"
  19 #include "dosutil.h"
  20
  21 #define PIT_TIMER_INTR  8
  22 #define DOS_TIMER_INTR  0x1c
  23
  24 /* macro to divide and round to the nearest integer */
  25 #define DIV_ROUND(a, b) \
  26         ((a) / (b) + ((a) % (b)) / ((b) / 2))
  27
  28 static void set_timer_reload(int reload_val);
  29 static void cleanup(void);
  30
  31 #ifdef __WATCOMC__
  32 #define INTERRUPT       __interrupt __far
  33
  34 static void INTERRUPT dos_timer_intr();
  35
  36 static void (INTERRUPT *prev_timer_intr)();
  37 #endif
  38
  39 #ifdef __DJGPP__
  40 #define INTERRUPT
  41
  42 static _go32_dpmi_seginfo intr, prev_intr;
  43 #endif
  44
  45 static void INTERRUPT timer_irq();
  46
  47 static volatile unsigned long ticks;
  48 static unsigned long tick_interval, ticks_per_dos_intr;
  49 static int inum;
  50
  51 void init_timer(int res_hz)
  52 {
  53         _disable();
  54
  55         if(res_hz > 0) {
  56                 int reload_val = DIV_ROUND(OSC_FREQ_HZ, res_hz);
  57                 set_timer_reload(reload_val);
  58
  59                 tick_interval = DIV_ROUND(1000, res_hz);
  60                 ticks_per_dos_intr = DIV_ROUND(65535L, reload_val);
  61
  62                 inum = PIT_TIMER_INTR;
  63 #ifdef __WATCOMC__
  64                 prev_timer_intr = _dos_getvect(inum);
  65                 _dos_setvect(inum, timer_irq);
  66 #endif
  67 #ifdef __DJGPP__
  68                 _go32_dpmi_get_protected_mode_interrupt_vector(inum, &prev_intr);
  69                 intr.pm_offset = (intptr_t)timer_irq;
  70                 intr.pm_selector = _go32_my_cs();
  71                 _go32_dpmi_allocate_iret_wrapper(&intr);
  72                 _go32_dpmi_set_protected_mode_interrupt_vector(inum, &intr);
  73 #endif
  74         } else {
  75                 tick_interval = 55;
  76
  77                 inum = DOS_TIMER_INTR;
  78 #ifdef __WATCOMC__
  79                 prev_timer_intr = _dos_getvect(inum);
  80                 _dos_setvect(inum, dos_timer_intr);
  81 #endif
  82 #ifdef __DJGPP__
  83                 assert(0);
  84 #endif
  85         }
  86         _enable();
  87
  88         atexit(cleanup);
  89 }
  90
  91 static void cleanup(void)
  92 {
  93         if(!inum) {
  94                 return; /* init hasn't ran, there's nothing to cleanup */
  95         }
  96
  97         _disable();
  98         if(inum == PIT_TIMER_INTR) {
  99                 /* restore the original timer frequency */
 100                 set_timer_reload(65535);
 101         }
 102
 103         /* restore the original interrupt handler */
 104 #ifdef __WATCOMC__
 105         _dos_setvect(inum, prev_timer_intr);
 106 #endif
 107 #ifdef __DJGPP__
 108         _go32_dpmi_set_protected_mode_interrupt_vector(inum, &prev_intr);
 109         _go32_dpmi_free_iret_wrapper(&intr);
 110 #endif
 111
 112         _enable();
 113 }
 114
 115 void reset_timer(void)
 116 {
 117         ticks = 0;
 118 }
 119
 120 unsigned long get_msec(void)
 121 {
 122         return ticks * tick_interval;
 123 }
 124
 125 void sleep_msec(unsigned long msec)
 126 {
 127         unsigned long wakeup_time = ticks + msec / tick_interval;
 128         while(ticks < wakeup_time) {
 129 #ifdef USE_HLT
 130                 halt();
 131 #endif
 132         }
 133 }
 134
 135 static void set_timer_reload(int reload_val)
 136 {
 137         outp(PORT_CMD, CMD_CHAN0 | CMD_ACCESS_BOTH | CMD_OP_SQWAVE);
 138         outp(PORT_DATA0, reload_val & 0xff);
 139         outp(PORT_DATA0, (reload_val >> 8) & 0xff);
 140 }
 141
 142 #ifdef __WATCOMC__
 143 static void INTERRUPT dos_timer_intr()
 144 {
 145         ticks++;
 146         _chain_intr(prev_timer_intr);   /* DOES NOT RETURN */
 147 }
 148 #endif
 149
 150 /* first PIC command port */
 151 #define PIC1_CMD        0x20
 152 /* end of interrupt control word */
 153 #define OCW2_EOI        (1 << 5)
 154
 155 static void INTERRUPT timer_irq()
 156 {
 157         static unsigned long dos_ticks;
 158
 159         ticks++;
 160
 161 #ifdef __WATCOMC__
 162         if(++dos_ticks >= ticks_per_dos_intr) {
 163                 /* I suppose the dos irq handler does the EOI so I shouldn't
 164                  * do it if I am to call the previous function
 165                  */
 166                 dos_ticks = 0;
 167                 _chain_intr(prev_timer_intr);   /* XXX DOES NOT RETURN */
 168                 return; /* just for clarity */
 169         }
 170 #endif
 171
 172         /* send EOI to the PIC */
 173         outp(PIC1_CMD, OCW2_EOI);
 174 }