vm.instruction.stream.js

"use strict";
/*
 * Copyright (c) 2013-2024 Vanessa Freudenberg
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

Object.subclass('Squeak.InstructionStream',
'initialization', {
    initialize: function(method, vm) {
        this.vm = vm;
        this.method = method;
        this.pc = 0;
        this.specialConstants = [vm.trueObj, vm.falseObj, vm.nilObj, -1, 0, 1, 2];
    },
},
'decoding', {
    interpretNextInstructionFor: function(client) {
        // Send to the argument, client, a message that specifies the type of the next instruction.
        var method = this.method;
        var byte = method.bytes[this.pc++];
        var type = (byte / 16) | 0;
        var offset = byte % 16;
        if (type === 0) return client.pushReceiverVariable(offset);
        if (type === 1) return client.pushTemporaryVariable(offset);
        if (type === 2) return client.pushConstant(method.methodGetLiteral(offset));
        if (type === 3) return client.pushConstant(method.methodGetLiteral(offset + 16));
        if (type === 4) return client.pushLiteralVariable(method.methodGetLiteral(offset));
        if (type === 5) return client.pushLiteralVariable(method.methodGetLiteral(offset + 16));
        if (type === 6)
            if (offset<8) return client.popIntoReceiverVariable(offset)
            else return client.popIntoTemporaryVariable(offset-8);
        if (type === 7) {
            if (offset===0) return client.pushReceiver()
            if (offset < 8) return client.pushConstant(this.specialConstants[offset - 1])
            if (offset===8) return client.methodReturnReceiver();
            if (offset < 12) return client.methodReturnConstant(this.specialConstants[offset - 9]);
            if (offset===12) return client.methodReturnTop();
            if (offset===13) return client.blockReturnTop();
            if (offset > 13) throw Error("unusedBytecode");
        }
        if (type === 8) return this.interpretExtension(offset, method, client);
        if (type === 9) // short jumps
                if (offset<8) return client.jump(offset+1);
                else return client.jumpIf(false, offset-8+1);
        if (type === 10) {// long jumps
            byte = this.method.bytes[this.pc++];
            if (offset<8) return client.jump((offset-4)*256 + byte);
            else return client.jumpIf(offset<12, (offset & 3)*256 + byte);
        }
        if (type === 11)
            return client.send(this.vm.specialSelectors[2 * offset],
                this.vm.specialSelectors[2 * offset + 1],
                false);
        if (type === 12)
            return client.send(this.vm.specialSelectors[2 * (offset + 16)],
                this.vm.specialSelectors[2 * (offset + 16) + 1],
                false);
        if (type > 12)
            return client.send(method.methodGetLiteral(offset), type-13, false);
    },
    interpretExtension: function(offset, method, client) {
        if (offset <= 6) { // Extended op codes 128-134
            var byte2 = this.method.bytes[this.pc++];
            if (offset <= 2) { // 128-130:  extended pushes and pops
                var type = byte2 / 64 | 0;
                var offset2 = byte2 % 64;
                if (offset === 0) {
                    if (type === 0) return client.pushReceiverVariable(offset2);
                    if (type === 1) return client.pushTemporaryVariable(offset2);
                    if (type === 2) return client.pushConstant(this.method.methodGetLiteral(offset2));
                    if (type === 3) return client.pushLiteralVariable(this.method.methodGetLiteral(offset2));
                }
                if (offset === 1) {
                    if (type === 0) return client.storeIntoReceiverVariable(offset2);
                    if (type === 1) return client.storeIntoTemporaryVariable(offset2);
                    if (type === 2) throw Error("illegalStore");
                    if (type === 3) return client.storeIntoLiteralVariable(this.method.methodGetLiteral(offset2));
                }
                if (offset === 2) {
                    if (type === 0) return client.popIntoReceiverVariable(offset2);
                    if (type === 1) return client.popIntoTemporaryVariable(offset2);
                    if (type === 2) throw Error("illegalStore");
                    if (type === 3) return client.popIntoLiteralVariable(this.method.methodGetLiteral(offset2));
                }
            }
            // 131-134 (extended sends)
            if (offset === 3) // Single extended send
                return client.send(this.method.methodGetLiteral(byte2 % 32), byte2 / 32 | 0, false);
            if (offset === 4) { // Double extended do-anything
                var byte3 = this.method.bytes[this.pc++];
                var type = byte2 / 32 | 0;
                if (type === 0) return client.send(this.method.methodGetLiteral(byte3), byte2 % 32, false);
                if (type === 1) return client.send(this.method.methodGetLiteral(byte3), byte2 % 32, true);
                if (type === 2) return client.pushReceiverVariable(byte3);
                if (type === 3) return client.pushConstant(this.method.methodGetLiteral(byte3));
                if (type === 4) return client.pushLiteralVariable(this.method.methodGetLiteral(byte3));
                if (type === 5) return client.storeIntoReceiverVariable(byte3);
                if (type === 6) return client.popIntoReceiverVariable(byte3);
                if (type === 7) return client.storeIntoLiteralVariable(this.method.methodGetLiteral(byte3));
            }
            if (offset === 5) // Single extended send to super
                return client.send(this.method.methodGetLiteral(byte2 & 31), byte2 >> 5, true);
            if (offset === 6) // Second extended send
                return client.send(this.method.methodGetLiteral(byte2 & 63), byte2 >> 6, false);
        }
        if (offset === 7) return client.doPop();
        if (offset === 8) return client.doDup();
        if (offset === 9) return client.pushActiveContext();
        // closures
        var byte2 = this.method.bytes[this.pc++];
        if (offset === 10)
            return byte2 < 128 ? client.pushNewArray(byte2) : client.popIntoNewArray(byte2 - 128);
        var byte3 = this.method.bytes[this.pc++];
        if (offset === 11) return client.callPrimitive(byte2 + 256 * byte3);
        if (offset === 12) return client.pushRemoteTemp(byte2, byte3);
        if (offset === 13) return client.storeIntoRemoteTemp(byte2, byte3);
        if (offset === 14) return client.popIntoRemoteTemp(byte2, byte3);
        // offset === 15
        var byte4 = this.method.bytes[this.pc++];
        return client.pushClosureCopy(byte2 >> 4, byte2 & 0xF, (byte3 * 256) + byte4);
    }
});