UInt24.ts

export class UInt24 {

    /**
     *16777215
     */
    public static readonly MaxVlaue: number = 0xFFFFFF;

    public static readonly MiniValue: number = 0;

    /**
     * 读一个 int24 
     * @param buffer 
     * @param offset 
     * @param littleEndian 
     */
    public static read(dataView: DataView, offset: number, littleEndian: boolean = false): number {
        if (littleEndian) {
            var number = dataView.getUint8(offset) | (dataView.getUint8(offset + 1) << 8) | (dataView.getUint8(offset + 2) << 16)
            return number
        }
        return dataView.getUint8(offset + 2) | (dataView.getUint8(offset + 1) << 8) | (dataView.getUint8(offset) << 16);

        // if (littleEndian) {
        //     var number= buffer[0 + offset] | (buffer[1 + offset] << 8) | (buffer[2 + offset] << 16)
        //     return number
        // }
        // return buffer[2 + offset] | (buffer[1 + offset] << 8) | (buffer[0 + offset] << 16);
    }

    /**
     * 写入 int24 
     * @param buffer buffer
     * @param value 写入的数字
     * @param offset 写入偏移量
     * @param littleEndian 默认大端
     */
    public static write(dataView: DataView, offset: number, value: number, littleEndian: boolean = false) {

        if (littleEndian) {
            var number = value & 0xff;
            dataView.setInt8(offset, number);

            var number = (value & 0xff00) >> 8;
            dataView.setInt8(offset + 1, number);

            var number = (value & 0xff0000) >> 16;
            dataView.setInt8(offset + 2, number);
        } else {
            var number = value & 0xff;
            dataView.setInt8(offset + 2, number);

            var number = (value & 0xff00) >> 8;
            dataView.setInt8(offset + 1, number);

            var number = (value & 0xff0000) >> 16;
            dataView.setInt8(offset, number);
        }

        // let buffer = dataView.buffer
        // if (littleEndian) {
        //     buffer[0 + offset] = value & 0xff;
        //     buffer[1 + offset] = (value & 0xff00) >> 8;
        //     buffer[2 + offset] = (value & 0xff0000) >> 16;
        // } else {
        //     buffer[2 + offset] = value & 0xff;
        //     buffer[1 + offset] = (value & 0xff00) >> 8;
        //     buffer[0 + offset] = (value & 0xff0000) >> 16;
        // }
    }

}