ref: 2d221e61e3820a007ff2204adb73ad3ab27010c6
dir: /sys/src/cmd/aux/realemu/pit.c/
#include <u.h> #include <libc.h> #include "dat.h" #include "fns.h" enum { AC0 = 0, AC1, AC2, Actl, Readback = 3, RBC0 = 1<<1, RBC1 = 1<<2, RBC2 = 1<<3, RBlatchstatus = 1<<4, RBlatchcount = 1<<5, AMlatchcount = 0, AMloonly, AMhionly, AMlohi, OM0 = 0, OM1, OM2, OM3, OM4, OM5, OM2b, OM3b, }; static void latchstatus(Pit *ch) { if(ch->rlatched) return; ch->rlatch[0] = ch->bcd | ch->omode<<1 | ch->amode<<4 | ch->count0<<6 | ch->out<<7; ch->rcount = 0; ch->rlatched = 1; } static void latchcount(Pit *ch) { ulong w; if(ch->rlatched) return; w = ch->count & 0xFFFF; if(ch->bcd) w = (w % 10) | ((w/10) % 10)<<4 | ((w/100) % 10)<<8 | ((w/1000) % 10)<<12; ch->rlatch[0] = w & 0xFF; ch->rlatch[1] = (w >> 8) & 0xFF; ch->rcount = 0; ch->rlatched = 1; switch(ch->amode){ case AMhionly: ch->rcount++; break; case AMlohi: ch->rlatched++; break; } } static void setcount(Pit *ch) { ulong w; w = (ulong)ch->wlatch[0] | (ulong)ch->wlatch[1] << 8; if(ch->bcd) w = (w & 0xF) + 10*((w >> 4)&0xF) + 100*((w >> 8)&0xF) + 1000*((w >> 12)&0xF); ch->count = w; ch->count0 = 0; } static int deccount(Pit *ch, vlong *cycles) { if(ch->count0){ *cycles = 0; return 0; } else { vlong passed, remain; passed = *cycles; if(ch->count == 0){ ch->count = ch->bcd ? 9999 : 0xFFFF; passed--; } if(passed <= ch->count){ remain = 0; ch->count -= passed; } else { remain = passed - ch->count; ch->count = 0; } *cycles = remain; return ch->count == 0; } } void setgate(Pit *ch, uchar gate) { if(ch->gate == 0 && gate) ch->gateraised = 1; ch->gate = gate; } static void clockpit1(Pit *ch, vlong *cycles) { switch(ch->omode){ case OM0: /* Interrupt On Terminal Count */ if(ch->count0){ setcount(ch); ch->out = 0; Next: --*cycles; return; } if(ch->gate && deccount(ch, cycles)){ ch->out = 1; return; } break; case OM1: /* Hardware Re-triggerable One-shot */ if(ch->gateraised){ ch->gateraised = 0; setcount(ch); ch->out = 0; goto Next; } if(deccount(ch, cycles) && ch->out == 0){ ch->out = 1; return; } break; case OM2: /* Rate Generator */ case OM2b: ch->out = 1; if(ch->count0){ setcount(ch); goto Next; } if(ch->gate == 0) break; if(ch->gateraised){ ch->gateraised = 0; setcount(ch); goto Next; } if(deccount(ch, cycles)){ setcount(ch); ch->out = 0; return; } break; case OM3: /* Square Wave Generator */ case OM3b: if(ch->count0){ setcount(ch); goto Next; } if(ch->gate == 0) break; if(ch->gateraised){ ch->gateraised = 0; setcount(ch); goto Next; } if(deccount(ch, cycles)){ setcount(ch); ch->out ^= 1; return; } break; case OM4: /* Software Triggered Strobe */ ch->out = 1; if(ch->count0){ setcount(ch); goto Next; } if(ch->gate && deccount(ch, cycles)){ ch->out = 0; return; } break; case OM5: /* Hardware Triggered Strobe */ ch->out = 1; if(ch->gateraised){ ch->gateraised = 0; setcount(ch); goto Next; } if(deccount(ch, cycles)){ ch->out = 0; return; } break; } *cycles = 0; } void clockpit(Pit *pit, vlong cycles) { Pit *ch; int i; if(cycles <= 0) return; for(i = 0; i<Actl; i++){ ch = pit + i; if(ch->wlatched){ vlong c; switch(ch->omode){ case OM3: case OM3b: c = cycles * 2; break; default: c = cycles; } while(c > 0) clockpit1(ch, &c); } ch->gateraised = 0; } } uchar rpit(Pit *pit, uchar addr) { Pit *ch; uchar data; if(addr >= Actl) return 0; ch = pit + addr; if(ch->rlatched){ data = ch->rlatch[ch->rcount & 1]; ch->rlatched--; } else { data = 0; switch(ch->amode){ case AMloonly: data = ch->count & 0xFF; break; case AMhionly: data = (ch->count >> 8) & 0xFF; break; case AMlohi: data = (ch->count >> ((ch->rcount & 1)<<3)) & 0xFF; break; } } ch->rcount++; if(0) fprint(2, "rpit %p: %.2x %.2x\n", pit, (int)addr, (int)data); return data; } void wpit(Pit *pit, uchar addr, uchar data) { Pit *ch; if(0) fprint(2, "wpit %p: %.2x %.2x\n", pit, (int)addr, (int)data); if(addr > Actl) return; if(addr == Actl){ uchar sc, amode, omode, bcd; bcd = (data & 1); omode = (data >> 1) & 7; amode = (data >> 4) & 3; sc = (data >> 6) & 3; if(sc == Readback){ ch = nil; for(;;){ if(data & RBC0){ ch = pit; break; } if(data & RBC1){ ch = pit + 1; break; } if(data & RBC2){ ch = pit + 2; break; } break; } if(ch == nil) return; if((data & RBlatchcount) == 0) latchcount(ch); if((data & RBlatchstatus) == 0) latchstatus(ch); return; } ch = pit + sc; if(amode == AMlatchcount){ latchcount(ch); return; } ch->bcd = bcd; ch->amode = amode; ch->omode = omode; ch->rlatched = 0; ch->rcount = 0; ch->rlatch[0] = 0; ch->rlatch[1] = 0; ch->wlatched = 0; ch->wcount = 0; ch->wlatch[0] = 0; ch->wlatch[1] = 0; ch->count0 = 1; ch->out = !!omode; return; } ch = pit + addr; switch(ch->amode){ case AMloonly: case AMhionly: ch->wlatch[ch->amode - AMloonly] = data; ch->wcount++; break; case AMlohi: ch->wlatch[ch->wcount++ & 1] = data; if(ch->wcount < 2) return; break; } ch->wlatched = ch->wcount; ch->wcount = 0; ch->count0 = 1; }