@awayfl/avm1/dist/lib/stream.js

Virtual machine for executing AS1 and AS2 code

/*
 * Copyright 2014 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
var ActionsDataStream = /** @class */ (function () {
    function ActionsDataStream(array, swfVersion) {
        this.array = array;
        this.position = 0;
        this.end = array.length;
        // TODO use system locale to determine if the shift-JIS
        // decoding is necessary
        this.readANSI = swfVersion < 6;
        // endianess sanity check
        var buffer = new ArrayBuffer(4);
        (new Int32Array(buffer))[0] = 1;
        if (!(new Uint8Array(buffer))[0]) {
            throw new Error('big-endian platform');
        }
    }
    ActionsDataStream.prototype.readUI8 = function () {
        return this.array[this.position++];
    };
    ActionsDataStream.prototype.readUI16 = function () {
        var position = this.position, array = this.array;
        var value = (array[position + 1] << 8) | array[position];
        this.position = position + 2;
        return value;
    };
    ActionsDataStream.prototype.readSI16 = function () {
        var position = this.position, array = this.array;
        var value = (array[position + 1] << 8) | array[position];
        this.position = position + 2;
        return value < 0x8000 ? value : (value - 0x10000);
    };
    ActionsDataStream.prototype.readInteger = function () {
        var position = this.position, array = this.array;
        var value = array[position] | (array[position + 1] << 8) |
            (array[position + 2] << 16) | (array[position + 3] << 24);
        this.position = position + 4;
        return value;
    };
    ActionsDataStream.prototype.readFloat = function () {
        var position = this.position;
        var array = this.array;
        var buffer = new ArrayBuffer(4);
        var bytes = new Uint8Array(buffer);
        bytes[0] = array[position];
        bytes[1] = array[position + 1];
        bytes[2] = array[position + 2];
        bytes[3] = array[position + 3];
        this.position = position + 4;
        return (new Float32Array(buffer))[0];
    };
    ActionsDataStream.prototype.readDouble = function () {
        var position = this.position;
        var array = this.array;
        var buffer = new ArrayBuffer(8);
        var bytes = new Uint8Array(buffer);
        bytes[4] = array[position];
        bytes[5] = array[position + 1];
        bytes[6] = array[position + 2];
        bytes[7] = array[position + 3];
        bytes[0] = array[position + 4];
        bytes[1] = array[position + 5];
        bytes[2] = array[position + 6];
        bytes[3] = array[position + 7];
        this.position = position + 8;
        return (new Float64Array(buffer))[0];
    };
    ActionsDataStream.prototype.readBoolean = function () {
        return !!this.readUI8();
    };
    ActionsDataStream.prototype.readANSIString = function () {
        var value = '';
        var ch;
        while ((ch = this.readUI8())) {
            value += String.fromCharCode(ch);
        }
        return value;
    };
    ActionsDataStream.prototype.readUTF8String = function () {
        var value = '';
        var ch;
        while ((ch = this.readUI8())) {
            if (ch < 0x80) {
                value += String.fromCharCode(ch);
                continue;
            }
            if ((ch & 0xC0) === 0x80) {
                // Invalid UTF8 encoding: initial char -- using it as is
                value += String.fromCharCode(ch);
                continue;
            }
            var lastPosition = this.position - 1; // in case if we need to recover
            var currentPrefix = 0xC0;
            var validBits = 5;
            do {
                var mask = (currentPrefix >> 1) | 0x80;
                if ((ch & mask) === currentPrefix) {
                    break;
                }
                currentPrefix = mask;
                --validBits;
            } while (validBits >= 0);
            var code = (ch & ((1 << validBits) - 1));
            for (var i = 5; i >= validBits; --i) {
                ch = this.readUI8();
                if ((ch & 0xC0) !== 0x80) {
                    // Invalid UTF8 encoding: bad chars in the tail, using previous chars as is
                    var skipToPosition = this.position - 1;
                    this.position = lastPosition;
                    while (this.position < skipToPosition) {
                        value += String.fromCharCode(this.readUI8());
                    }
                    continue;
                }
                code = (code << 6) | (ch & 0x3F);
            }
            if (code >= 0x10000) {
                value += String.fromCharCode((((code - 0x10000) >> 10) & 0x3FF) |
                    0xD800, (code & 0x3FF) | 0xDC00);
            }
            else {
                value += String.fromCharCode(code);
            }
        }
        return value;
    };
    ActionsDataStream.prototype.readString = function () {
        return this.readANSI ? this.readANSIString() : this.readUTF8String();
    };
    ActionsDataStream.prototype.readBytes = function (length) {
        var position = this.position;
        var remaining = Math.max(this.end - position, 0);
        if (remaining < length) {
            length = remaining;
        }
        var subarray = this.array.subarray(position, position + length);
        this.position = position + length;
        return subarray;
    };
    return ActionsDataStream;
}());
export { ActionsDataStream };