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lynxerzhang/ByteArray.js

Created May 25, 2017 08:50
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  1. lynxerzhang created this gist May 25, 2017.
    122 changes: 122 additions & 0 deletions ByteArray.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,122 @@
    //在构造函数中创建了一个DataView对象和一个position变量追踪当前指针指向哪个字节。
    class ByteArray extends ArrayBuffer
    {
    constructor(...args) {
    super(...args);
    this.dataView = new DataView(this);
    this.position = 0;
    }

    get length(){
    return this.byteLength;
    }

    get bytesAvailable(){
    let diff = this.byteLength - this.position;
    if(diff < 0){
    diff = 0;
    }
    return diff;
    }

    writeInt8(value){
    this.dataView.setInt8(this.position, value);
    this.position += 1;
    }

    writeUint8(value){
    this.dataView.setUint8(this.position, value);
    this.position += 1;
    }

    writeInt16(value){
    this.dataView.setInt16(this.position, value);
    this.position += 2;
    }

    writeUint16(value){
    this.dataView.setUint16(this.position, value);
    this.position += 2;
    }

    writeInt32(value){
    this.dataView.setInt32(this.position, value);
    this.position += 4;
    }

    writeUint32(value){
    this.dataView.setUint32(this.position, value);
    this.position += 4;
    }

    writeFloat32(value){
    this.dataView.setFloat32(this.position, value);
    this.position += 4;
    }

    writeFloat64(value){
    this.dataView.setFloat64(this.position, value);
    this.position += 8;
    }

    readInt8(){
    let result = this.dataView.getInt8(this.position);
    this.position += 1;
    return result;
    }

    readUint8(){
    let result = this.dataView.getUint8(this.position);
    this.position += 1;
    return result;
    }

    readInt16(){
    let result = this.dataView.getInt16(this.position);
    this.position += 2;
    return result;
    }

    readUint16(){
    let result = this.dataView.getUint16(this.position);
    this.position += 2;
    return result;
    }

    readInt32(){
    let result = this.dataView.getInt32(this.position);
    this.position += 4;
    return result;
    }

    readUint32(){
    let result = this.dataView.getUint32(this.position);
    this.position += 4;
    return result;
    }

    readFloat32(){
    let result = this.dataView.getFloat32(this.position);
    this.position += 4;
    return result;
    }

    readFloat64(){
    let result = this.dataView.getFloat64(this.position);
    this.position += 8;
    return result;
    }
    }

    //example
    var ds = new ByteArray(32);
    console.log("length is:", ds.length, "position is:", ds.position, "bytesAvaliable is:", ds.bytesAvailable); //32, 0, 32

    ds.writeInt32(10); //作为32位的整数写入（4个字节）
    ds.writeInt16(12); //作为16位的整数写入（2个字节）

    console.log("length is:", ds.length, "position is:", ds.position, "bytesAvaliable is:", ds.bytesAvailable); //32, 6, 26

    ds.position = 0;
    console.log(ds.readInt32()); //10
    console.log(ds.readInt16()); //12