sys/src/games/gb/ev.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <thread.h>
   4 #include "dat.h"
   5 #include "fns.h"
   6
   7 Event evhblank, evtimer, evenv;
   8 extern Event evsamp, chev[4];
   9 Event *events[NEVENT] = {&evhblank, &evtimer, &evenv, &evsamp, &chev[0], &chev[1], &chev[2], &chev[3]};
  10 Event *elist;
  11 static int timshtab[4] = {12, 4, 6, 8}, timsh;
  12 ulong timclock;
  13 Var evvars[] = {VAR(timsh), VAR(timclock), {nil, 0, 0}};
  14
  15 void
  16 addevent(Event *ev, int time)
  17 {
  18         Event **p, *e;
  19         int t;
  20
  21         assert(time >= 0);
  22         t = time;
  23         for(p = &elist; (e = *p) != nil; p = &e->next){
  24                 if(t < e->time){
  25                         e->time -= t;
  26                         break;
  27                 }
  28                 t -= e->time;
  29         }
  30         ev->next = e;
  31         ev->time = t;
  32         *p = ev;
  33 }
  34
  35 void
  36 delevent(Event *ev)
  37 {
  38         Event **p, *e;
  39
  40         for(p = &elist; (e = *p) != nil; p = &e->next)
  41                 if(e == ev){
  42                         *p = e->next;
  43                         if(e->next != nil)
  44                                 e->next->time += e->time;
  45                         return;
  46                 }
  47 }
  48
  49 void
  50 popevent(void)
  51 {
  52         Event *e;
  53         int t;
  54
  55         do{
  56                 e = elist;
  57                 t = e->time;
  58                 elist = e->next;
  59                 e->f(e->aux);
  60         }while((elist->time += t) <= 0);
  61 }
  62
  63 void
  64 timerset(void)
  65 {
  66         timclock = clock & -(1<<timsh);
  67         if((reg[TAC] & 4) != 0){
  68                 delevent(&evtimer);
  69                 addevent(&evtimer, 0x100 - reg[TIMA] << timsh);// | -clock & (1<<timsh)-1);
  70         }
  71 }
  72
  73 void
  74 timertac(u8int n, int t)
  75 {
  76         if((reg[TAC] & 7) == (n & 7) && !t)
  77                 return;
  78         if((reg[TAC] & 4) != 0){
  79                 delevent(&evtimer);
  80                 reg[TIMA] += clock - timclock >> timsh;
  81         }
  82         timclock = clock & -(1<<timsh);
  83         timsh = timshtab[n & 3];
  84         if((mode & TURBO) == 0)
  85                  timsh++;
  86         if((n & 4) != 0)
  87                 addevent(&evtimer, 0x100 - reg[TIMA] << timsh | -clock & (1<<timsh)-1);
  88 }
  89
  90 u8int
  91 timread(void)
  92 {
  93         if((reg[TAC] & 4) == 0)
  94                 return reg[TIMA];
  95         return reg[TIMA] + (clock - timclock >> timsh);
  96 }
  97
  98 void
  99 timertick(void *)
 100 {
 101         reg[TIMA] = reg[TMA];
 102         addevent(&evtimer, 0x100 - reg[TIMA] << timsh);
 103         reg[IF] |= IRQTIM;
 104 }
 105
 106 void
 107 eventinit(void)
 108 {
 109         extern void hblanktick(void *);
 110         extern void envtick(void *);
 111         extern void wavetick(void *);
 112         extern void chantick(void *);
 113
 114         evhblank.f = hblanktick;
 115         addevent(&evhblank, 240*4);
 116         evtimer.f = timertick;
 117         evenv.f = envtick;
 118         addevent(&evenv, FREQ / 512);
 119         chev[0].f = chantick;
 120         chev[1].f = chantick;
 121         chev[2].f = chantick;
 122         chev[3].f = chantick;
 123 }