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tube.js
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tube.js
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"use strict";
import * as utils from "./utils.js";
export class Tube {
constructor(hostCpu, parasiteCpu) {
this.hostCpu = hostCpu;
this.parasiteCpu = parasiteCpu;
this.ph1 = new Uint8Array(24);
this.ph2 = 0;
this.ph3 = new Uint8Array(2);
this.ph4 = 0;
this.hp1 = 0;
this.hp2 = 0;
this.hp3 = new Uint8Array(2);
this.hp4 = 0;
this.hstat = new Uint8Array(4);
this.pstat = new Uint8Array(4);
this.r1stat = 0;
this.ph1pos = 0;
this.ph3pos = 0;
this.hp3pos = 0;
this.debug = false;
}
updateInterrupts() {
// Host interrupt
this.hostCpu.interrupt &= ~8;
if (this.r1stat & 0x01 && this.hstat[3] & 0x80) this.hostCpu.interrupt |= 8;
// Parasite interrupts
this.parasiteCpu.interrupt = !!(
(this.r1stat & 0x02 && this.pstat[0] & 0x80) ||
(this.r1stat & 0x04 && this.pstat[3] & 0x80)
);
const hp3Size = this.r1stat & 0x10 ? 1 : 0;
this.parasiteCpu.nmi = !!(this.r1stat & 0x08 && (this.hp3pos > hp3Size || this.ph3pos === 0));
}
reset() {
this.ph1pos = this.hp3pos = 0;
this.ph3pos = 1;
this.r1stat = 0;
this.hstat[0] = this.hstat[1] = this.hstat[3] = 0x40;
this.hstat[2] = 0xc0;
this.pstat[0] = this.pstat[1] = this.pstat[2] = this.pstat[3] = 0x40;
}
hostRead(addr) {
let result = 0xfe;
switch (addr & 7) {
case 0:
result = (this.hstat[0] & 0xc0) | this.r1stat;
break;
case 1:
result = this.ph1[0];
for (let i = 0; i < 23; ++i) this.ph1[i] = this.ph1[i + 1];
this.pstat[0] |= 0x40;
if (!--this.ph1pos) {
this.hstat[0] &= ~0x80;
}
break;
case 2:
result = this.hstat[1];
break;
case 3:
result = this.ph2;
if (this.hstat[1] & 0x80) {
this.hstat[1] &= ~0x80;
this.pstat[1] |= 0x40;
}
break;
case 4:
result = this.hstat[2];
break;
case 5:
result = this.ph3[0];
if (this.ph3pos > 0) {
this.ph3[0] = this.ph3[1];
this.pstat[2] |= 0xc0;
if (!--this.ph3pos) this.hstat[2] &= ~0x80;
}
break;
case 6:
result = this.hstat[3];
break;
case 7:
result = this.ph4;
if (this.hstat[3] & 0x80) {
this.hstat[3] &= ~0x80;
this.pstat[3] |= 0x40;
}
break;
}
this.updateInterrupts();
if (this.debug) console.log("host read " + utils.hexword(addr) + " = " + utils.hexbyte(result));
return result;
}
hostWrite(addr, b) {
if (this.debug) console.log("host write " + utils.hexword(addr) + " = " + utils.hexbyte(b));
switch (addr & 7) {
case 0:
if (b & 0x80) this.r1stat |= b & 0x3f;
else this.r1stat &= ~(b & 0x3f);
this.hstat[0] = (this.hstat[0] & 0xc0) | (b & 0x3f);
break;
case 1:
this.hp1 = b;
this.pstat[0] |= 0x80;
this.hstat[0] &= ~0x40;
break;
case 3:
this.hp2 = b;
this.pstat[1] |= 0x80;
this.hstat[1] &= ~0x40;
break;
case 5:
if (this.r1stat & 0x10) {
if (this.hp3pos < 2) this.hp3[this.hp3pos++] = b;
if (this.hp3pos === 2) {
this.pstat[2] |= 0x80;
this.hstat[2] &= ~0x40;
}
} else {
this.hp3[0] = b;
this.hp3pos = 1;
this.pstat[2] |= 0x80;
this.hstat[2] &= ~0x40;
}
break;
case 7:
this.hp4 = b;
this.pstat[3] |= 0x80;
this.hstat[3] &= ~0x40;
break;
}
this.updateInterrupts();
}
parasiteRead(addr) {
let result = 0;
switch (addr & 7) {
case 0: // Stat
result = this.pstat[0] | this.r1stat;
break;
case 1:
result = this.hp1;
if (this.pstat[0] & 0x80) {
this.pstat[0] &= ~0x80;
this.hstat[0] |= 0x40;
}
break;
case 2:
result = this.pstat[1];
break;
case 3:
result = this.hp2;
if (this.pstat[1] & 0x80) {
this.pstat[1] &= ~0x80;
this.hstat[1] |= 0x40;
}
break;
case 4:
result = this.pstat[2];
break;
case 5:
result = this.hp3[0];
if (this.hp3pos > 0) {
this.hp3[0] = this.hp3[1];
if (!--this.hp3pos) {
this.pstat[2] &= ~0x80;
this.hstat[2] |= 0x40;
}
}
break;
case 6:
result = this.pstat[3];
break;
case 7:
result = this.hp4;
if (this.pstat[3] & 0x80) {
this.pstat[3] &= ~0x80;
this.hstat[3] |= 0x40;
}
break;
}
this.updateInterrupts();
if (this.debug) console.log("parasite read " + utils.hexword(addr) + " = " + utils.hexbyte(result));
return result;
}
parasiteWrite(addr, b) {
if (this.debug) console.log("parasite write " + utils.hexword(addr) + " = " + utils.hexbyte(b));
switch (addr & 7) {
case 1:
if (this.ph1pos < 24) {
this.ph1[this.ph1pos++] = b;
this.hstat[0] |= 0x80;
if (this.ph1pos === 24) this.pstat[0] &= ~0x40;
}
break;
case 3:
this.ph2 = b;
this.hstat[1] |= 0x80;
this.pstat[1] &= ~0x40;
break;
case 5:
if (this.r1stat & 0x10) {
if (this.ph3pos < 2) this.ph3[this.ph3pos++] = b;
if (this.ph3pos === 2) {
this.hstat[2] |= 0x80;
this.pstat[2] &= ~0x40;
}
} else {
this.ph3[0] = b;
this.ph3pos = 1;
this.hstat[2] |= 0x80;
this.pstat[2] &= ~0xc0;
}
break;
case 7:
this.ph4 = b;
this.hstat[3] |= 0x80;
this.pstat[3] &= ~0x40;
break;
}
this.updateInterrupts();
}
}