531 lines
15 KiB
JavaScript
Executable File
531 lines
15 KiB
JavaScript
Executable File
op = require("./opcodes");
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var INT_MIN = 0x80000000;
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var INT_MAX = 0x7FFFFFFF;
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var verbose = false;
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function log(message) {
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if (verbose) console.log(message);
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}
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function c0_assertion_failure(val) {
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throw ("c0 assertion failure: " + val);
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}
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function c0_memory_error(val) {
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throw ("c0 memory error: " + val);
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}
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function num_to_i32(num) {
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log("num is 0x" + num.toString(16));
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log("num & 0x7FFFFFFF is " + (num & 0x7FFFFFFF));
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log("neg factor is " + ( (num & 0x80000000)));
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return (num & 0x7FFFFFFF) + ((num & 0x80000000));
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}
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function i32_to_array(i32) {
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return [(i32 & 0xFF),
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((i32 >> 8) & 0xFF),
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((i32 >> 16) & 0xFF),
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((i32 >> 24) & 0xFF)];
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}
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function array_to_i32(array) {
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return array[0] +
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(array[1] << 8) +
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(array[2] << 16) +
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(array[3] << 24);
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}
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var StackFrame = function(file, f) {
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log("Creating stack frame");
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this.stack = [];
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this.pc = 0;
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this.program = f.code;
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this.function_id = f.function_id;
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this.variables = [];
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for (var i = 0; i < f.num_vars; i++)
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this.variables.push(0);
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this.file = file;
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}
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var ProgramState = function(parsed_file, callback_dict) {
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log("Creating program state with file " + parsed_file);
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var main_function = parsed_file.function_pool[0];
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this.frame = new StackFrame(parsed_file, parsed_file.function_pool[0]);
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this.call_stack = [];
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this.file = parsed_file;
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this.natives = {};
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for (var i = 0; i < 95; i++) {
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try {
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this.natives[i] = callback_dict[i];
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} catch (key_not_found) {
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this.natives[i] = function (arg) {
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console.log("Native function " + name + " called, ran method stub.");
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return 0;
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};
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}
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}
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this.breakpoints = [];
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// Memory is just a big array of bytes, right?
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// "Allocation" is appending onto this array
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// A pointer to memory is an index into this array.
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// Structs are stored as themselves
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// Arrays are stored as an entry for the number of elements
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// and then the array, byte-by-byte
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this.heap = [];
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}
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ProgramState.prototype.push = function(val) {
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this.frame.stack.push(val);
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}
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ProgramState.prototype.pop = function() {
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if (this.frame.stack === [])
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throw "Tried to pop from an empty stack!";
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return this.frame.stack.pop();
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}
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ProgramState.prototype.goto_offset = function() {
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var c1 = this.frame.program[this.frame.pc+1];
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var c2 = this.frame.program[this.frame.pc+2]
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var address_offset = (c1 << 8) + c2;
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// Handle negative values
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if ((address_offset & 0x8000) != 0)
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address_offset = -0x8000 + (address_offset & 0x7FFF);
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this.frame.pc += address_offset;
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}
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ProgramState.prototype.doIf = function(f) {
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var y = this.pop();
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var x = this.pop();
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if (f(x,y)) {
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this.goto_offset();
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} else {
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this.frame.pc += 3;
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}
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}
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ProgramState.prototype.step = function() {
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var opcode = this.frame.program[this.frame.pc]
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log("0x" + this.frame.pc.toString(16) + " Running opcode " +
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op.lookup_table[opcode]);
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switch (opcode) {
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// Stack manipulation
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case op.POP:
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this.frame.pc++;
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this.pop();
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break;
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case op.DUP:
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this.frame.pc++;
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var v = this.pop();
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this.push(v);
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this.push(v);
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break;
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case op.SWAP:
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this.frame.pc++;
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var v1 = this.pop();
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var v2 = this.pop();
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this.push(v1);
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this.push(v2);
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break;
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case op.BIPUSH:
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this.frame.pc += 2;
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var val = this.frame.program[this.frame.pc-1];
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// Do sign extension if necessary
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if ((val & 0x80) != 0)
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val = -0x80 + (val & 0x7F);
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this.push(val);
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break;
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// Returning from a function
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case op.RETURN:
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var retVal = this.pop();
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if (this.call_stack.length == 0)
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return retVal;
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this.frame = this.call_stack.pop();
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this.push(retVal);
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break;
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// Arithmetic
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case op.IADD:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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log("Adding " + x + " and " + y);
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this.push(num_to_i32(x+y));
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break;
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case op.ISUB:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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log("Subtracting " + x + " and " + y);
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this.push(num_to_i32(x-y));
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break;
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case op.IMUL:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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this.push(num_to_i32(x*y));
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break;
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case op.IDIV:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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if (y == 0) c0_arith_error("Divide by zero");
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if (x == INT_MIN && y == -1) c0_arith_error("Arithmetic overflow");
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// This does int division.
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// As I understand it, the ~~ is treated as the identity on integers
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// which forces the type to int, not float
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this.push(~~(x/y));
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break;
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case op.IREM:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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if (y == 0) c0_arith_error("Divide by zero");
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if (x == INT_MIN && y == -1) c0_arith_error("Arithmetic overflow");
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this.push(x%y);
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break;
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case op.IAND:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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this.push(x&y);
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break;
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case op.IOR:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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this.push(x|y);
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break;
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case op.IXOR:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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this.push(x^y);
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break;
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case op.ISHL:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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if (y < 0 || y > 31) c0_arith_error("Shifting by too many bits");
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this.push(x<<y);
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break;
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case op.ISHR:
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this.frame.pc++;
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var y = this.pop();
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var x = this.pop();
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if (y < 0 || y > 31) c0_arith_error("Shifting by too many bits");
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this.push(x>>y);
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break;
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// Operations on local variables
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case op.VLOAD:
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this.frame.pc += 2;
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var index = this.frame.program[this.frame.pc-1];
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this.push(this.frame.variables[index]);
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break;
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case op.VSTORE:
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this.frame.pc += 2;
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var index = this.frame.program[this.frame.pc-1];
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var val = this.pop();
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this.frame.variables[index] = val;
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log("Set variable " + index + " to value " + val);
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break;
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case op.ACONST_NULL:
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this.frame.pc++;
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this.push(0);
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break;
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case op.ILDC:
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this.frame.pc += 3;
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var c1 = this.frame.program[this.frame.pc-2];
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var c2 = this.frame.program[this.frame.pc-1];
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var index = (c1 * 0x1000) + c2;
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this.push(this.file.int_pool[index]);
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break;
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case op.ALDC:
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this.frame.pc += 3;
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var c1 = this.frame.program[this.frame.pc-2];
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var c2 = this.frame.program[this.frame.pc-1];
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var index = (c1 * 0x1000) + c2;
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this.push(this.file.string_from_index(index));
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break;
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// Control flow
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case op.NOP:
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this.frame.pc++;
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break;
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case op.IF_CMPEQ:
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this.doIf(function (x,y) {return y == x;});
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break;
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case op.IF_CMPNE:
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this.doIf(function (x,y) {return y != x;});
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break;
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case op.IF_ICMPLT:
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this.doIf(function (x,y) {return y > x;});
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break;
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case op.IF_ICMPGE:
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this.doIf(function (x,y) {return y <= x;});
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break;
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case op.IF_ICMPGT:
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this.doIf(function (x,y) {return y < x;});
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break;
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case op.IF_ICMPLE:
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this.doIf(function (x,y) {return y >= x;});
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break;
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case op.GOTO:
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this.goto_offset();
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break;
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case op.ATHROW:
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this.frame.pc++;
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c0_user_error(this.pop());
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break;
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case op.ASSERT:
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this.frame.pc++;
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var a = this.pop();
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if (this.pop() == 0)
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c0_assertion_failure(a);
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break;
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// Function call operations
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case op.INVOKESTATIC:
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var c1 = this.frame.program[this.frame.pc+1];
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var c2 = this.frame.program[this.frame.pc+2];
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this.frame.pc += 3;
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var index = (c1 << 8) + c2;
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var f = this.file.function_pool[index];
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var newFrame = new StackFrame(this.file, f);
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for (var i = f.num_args - 1; i >= 0; i--) {
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newFrame.variables[i] = this.pop();
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}
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this.call_stack.push(this.frame);
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this.frame = newFrame;
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break;
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case op.INVOKENATIVE:
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var c1 = this.frame.program[this.frame.pc+1];
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var c2 = this.frame.program[this.frame.pc+2];
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this.frame.pc += 3;
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var index = (c1 << 8) + c2;
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var f = this.file.native_pool[index];
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var arg_array = [];
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for (var i = f.num_args - 1; i >= 0; i--)
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arg_array[i] = this.pop();
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var native_function = this.natives[f.function_table_index];
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if (native_function === undefined) {
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native_function = function (ignored) {
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console.log("Could not find native function with index " +
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f.function_table_index);
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return 0;
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};
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console.log("Unknown native function index " + f.function_table_index);
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}
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log("Calling native function with index " + index + " with arguments " +
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arg_array);
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this.push(native_function(arg_array, this));
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break;
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// Memory allocation operations:
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case op.NEW:
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var size = this.frame.program[this.frame.pc+1];
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var address = this.heap.length;
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for (var i = 0; i < size; i++) this.heap.push(0);
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this.push(address);
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this.frame.pc += 2;
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break;
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case op.NEWARRAY:
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var size = this.frame.program[this.frame.pc+1];
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var address = this.heap.length;
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var num_elements = this.pop();
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if (num_elements < 0) c0_memory_error("Array size must be nonnegative");
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this.heap.push(num_elements);
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this.heap.push(size);
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for (var i = 0; i < num_elements; i++) {
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for (var j = 0; j < size; j++)
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this.heap.push(0);
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}
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this.push(address);
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this.frame.pc += 2;
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break;
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case op.ARRAYLENGTH:
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var pointer = this.pop();
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this.push(this.heap[pointer]);
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break;
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// Memory access operations:
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case op.AADDF:
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// Read offset into a struct
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var offset = this.frame.program[this.frame.pc + 1];
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var index = this.pop();
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this.push(index + offset);
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this.frame.pc += 2;
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break;
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case op.AADDS:
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// Read offset into an array
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var elt_index = this.pop();
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var index = this.pop();
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if (typeof index == "string") {
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this.push(index.slice(elt_index));
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} else {
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var array_length = this.heap[index];
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var elt_size = this.heap[index+1];
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if (elt_index >= array_length)
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c0_memory_error("Array index out of bounds.");
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this.push(index + 2 + (elt_size*elt_index));
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}
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this.frame.pc++;
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break;
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case op.IMLOAD:
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var addr = this.pop();
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// Get int32 from bytes
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var c1 = this.heap[addr];
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var c2 = this.heap[addr+1];
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var c3 = this.heap[addr+2];
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var c4 = this.heap[addr+3];
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var combined = array_to_i32([c1, c2, c3, c4]);
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this.push(combined);
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this.frame.pc++;
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break;
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case op.IMSTORE:
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var value = this.pop();
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var addr = this.pop();
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var array = i32_to_array(value);
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for (var i = 0; i < 4; i++)
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this.heap[addr + i] = array[i];
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this.frame.pc++;
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break;
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case op.AMLOAD:
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var addr = this.pop();
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this.push(this.heap[addr]);
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this.frame.pc++;
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break;
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case op.AMSTORE:
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var value = this.pop();
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var addr = this.pop();
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this.heap[addr] = value;
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this.frame.pc++;
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break;
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case op.CMLOAD:
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var addr = this.pop();
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if (typeof addr == "string")
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this.push(addr);
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else
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this.push(this.heap[addr]);
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this.frame.pc++;
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break;
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case op.CMSTORE:
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var value = this.pop();
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var addr = this.pop();
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this.heap[addr] = value;
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this.frame.pc++;
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break;
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default:
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var opcode_name;
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try {
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opcode_name = op.lookup_table[opcode];
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} catch (ignored) {
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opcode_name = "UNKNOWN";
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}
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console.log("Error: Unknown opcode: 0x" + opcode.toString(16) +
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" (" + opcode_name + ")\n");
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throw "Error - unknown opcode";
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}
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}
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ProgramState.prototype.set_breakpoint = function(function_index, opcode_index) {
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this.breakpoints.push([function_index, opcode_index]);
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}
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function initialize_vm(file, callbacks, v) {
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verbose = typeof v !== 'undefined' ? v : true;
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log("Initializing with file " + file);
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var state = new ProgramState(file, callbacks);
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if (verbose) log(file);
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log("Beginning execution");
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return state;
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}
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function run_vm(vm) {
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while (true) {
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for (breakpoint in vm.breakpoints) {
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if (vm.frame.function_id == breakpoint[0] &&
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vm.frame.pc == breakpoint[1]) {
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console.log("Breakpoint reached!");
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return vm;
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}
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}
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var val = vm.step();
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if (val !== undefined) return val;
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if (verbose) {
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console.log("Machine vm:");
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console.log(" Current Stack Frame:");
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console.log(" Stack: " + vm.frame.stack);
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console.log(" PC: " + vm.frame.pc);
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console.log(" Vars: " + vm.frame.variables);
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// console.log(" Code: " + vm.frame.program);
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console.log(" Heap: " + vm.heap);
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}
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}
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}
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// if (at_breakpoint) {
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// save state (maybe in a global in this file?)
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// return;
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// }
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// Takes in a parsed .bc0 file and runs it
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function execute(file, callbacks, v) {
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var state = initialize_vm(file, callbacks, v);
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return run_vm(state);
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}
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exports.execute = execute;
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exports.initialize_vm = initialize_vm;
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exports.run_vm = run_vm;
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