begin writing vm

3 files changed, 194 insertions, 0 deletions

diff --git a/src/vm/core.js b/src/vm/core.js
new file mode 100644
index 0000000..292ceb0
--- /dev/null
+++ b/src/vm/core.js
@@ -0,0 +1,51 @@
+'use strict';
+
+const { Op, AddrMode} = require('./enum.js');
+
+
+class Core {
+	constructor(size) {
+		this.data = new Array(size);
+
+		// initialize core to all DAT 0, 0
+		for (let i=0; i<size; i++) {
+			this.data[i] = {
+				opcode: Op.DAT,
+				a: { value: 0, mode: AddrMode.Direct },
+				b: { value: 0, mode: AddrMode.Direct },
+			};
+		}
+	}
+
+
+	normalize(pc, value) {
+		return (pc + value) % this.data.length;
+	}
+
+
+	getLocation(pc, address) {
+		switch(address.mode) {
+			case AddrMode.Immediate:
+				throw "Cannot get location from immediate-mode address";
+			case AddrMode.Direct:
+				return this.normalize(pc, address.value);
+			case AddrMode.Indirect: {
+				let loc = this.normalize(pc, address.value);
+				let b = this.data[loc];
+				return this.normalize(loc, b);
+			}
+			case AddrMode.Predecrement: {
+				let loc = this.normalize(pc, address.value);
+				this.data[loc].b -= 1;
+				let b = this.data[loc].b;
+				return this.normalize(loc, b);
+			}
+			default:
+				throw `Invalid addressing mode "${address.mode}"`;
+		}
+	}
+
+	getValue(pc, address) {
+		return this.data[this.getLocation(pc, address)];
+	}
+}
diff --git a/src/vm/enum.js b/src/vm/enum.js
new file mode 100644
index 0000000..5271991
--- /dev/null
+++ b/src/vm/enum.js
@@ -0,0 +1,27 @@
+'use strict';
+
+const Op = {
+	DAT: 'DAT',
+	MOV: 'MOV',
+	ADD: 'ADD',
+	SUB: 'SUB',
+	JMP: 'JMP',
+	JMZ: 'JMZ',
+	JMN: 'JMN',
+	CMP: 'CMP',
+	SLT: 'SLT',
+	DJN: 'DJN',
+	SPL: 'SPL',
+};
+
+
+const AddrMode = {
+	Immediate: 'immediate',
+	Indirect: 'indirect',
+	Predecrement: 'predecrement',
+	Direct: 'direct',
+};
+
+
+exports.Op = Op;
+exports.AddrMode = AddrMode;
diff --git a/src/vm/instruction.js b/src/vm/instruction.js
new file mode 100644
index 0000000..0fe922d
--- /dev/null
+++ b/src/vm/instruction.js
@@ -0,0 +1,116 @@
+'use strict';
+
+const { AddrMode } = require('./enum.js');
+
+
+function DoDat(core, pc, ins) {
+	// do nothing
+	return [];
+}
+
+
+function DoMov(core, pc, ins) {
+	if (ins.a.mode === AddrMode.Immediate) {
+		let mem = core.getValue(pc, ins.b);
+		mem.b.value = ins.a.value;
+	} else {
+		const src = core.getValue(pc, ins.a);
+		const dstLoc = core.getLocation(pc, ins.b);
+
+		// hacky deep copy
+		core.data[dstLoc] = JSON.parse(JSON.stringify(src));
+	}
+	return [pc + 1];
+}
+
+
+function DoAdd(core, pc, ins) {
+	if (ins.a.mode === AddrMode.Immediate) {
+		let dst = core.getValue(pc, ins.b);
+		dst.b += ins.a.value;
+	} else {
+		let src = core.getValue(pc, ins.a);
+		let dst = core.getValue(pc, ins.b);
+		dst.a.value += src.a.value;
+		dst.b.value += src.b.value;
+	}
+	return [pc + 1];
+}
+
+
+function DoSub(core, pc, ins) {
+	if (ins.a.mode === AddrMode.Immediate) {
+		let dst = core.getValue(pc, ins.b);
+		dst.b -= ins.a.value;
+	} else {
+		let src = core.getValue(pc, ins.a);
+		let dst = core.getValue(pc, ins.b);
+		dst.a.value -= src.a.value;
+		dst.b.value -= src.b.value;
+	}
+	return [pc + 1];
+}
+
+
+function DoJmp(core, pc, ins) {
+	return [core.getLocation(pc, ins.a)];
+}
+
+
+function DoJmz(core, pc, ins) {
+	let test
+	if (ins.b.mode === AddrMode.Immediate) {
+		test = ins;
+	} else {
+		test = core.getValue(pc, ins.b);
+	}
+
+	if (test.b.value === 0) {
+		return [core.getLocation(pc, ins.a)];
+	} else {
+		return [pc + 1];
+	}
+}
+
+
+function DoJmn(core, pc, ins) {
+	let test
+	if (ins.b.mode === AddrMode.Immediate) {
+		test = ins;
+	} else {
+		test = core.getValue(pc, ins.b);
+	}
+
+	if (test.b.value !== 0) {
+		return [core.getLocation(pc, ins.a)];
+	} else {
+		return [pc + 1];
+	}
+}
+
+
+function DoCmp(core, pc, ins) {
+	if (ins.a.mode === AddrMode.Immediate) {
+		const test = core.getValue(pc, ins.b);
+		if (ins.a.value === test.b.value) {
+			return [pc + 2];
+		} else {
+			return [pc + 1];
+		}
+	} else {
+		const a = core.getValue(pc, ins.a);
+		const b = core.getValue(pc, ins.b);
+
+		if (
+			a.opcode === b.opcode &&
+			a.a.value === b.a.value &&
+			a.b.value === b.b.value)
+		) {
+			return [pc + 2];
+		} else {
+			return [pc + 1];
+		}
+	}
+}
+
+