XNA skip simple algorithms and code

Just a friend asked me how to implement the jump. In fact, I don't know about xna either. In Zzk, there is no matching record for searching "XNA jump". I was a little impulsive when I was surprised. Do I have to do it myself? But xna really doesn't understand it. I found two or three source codes, and I was really stupid. I was so sorry to understand its algorithm. Simply implement it from the ground up by yourself. The reason to consider taking off from reality is the Take-off Speed (v1) weight (w) gravity g, which cannot be remembered according to the physical xxx, simple is perfect:

Global parameters:

        private bool _isJumping;        private bool _jumpKeyDown;        private float _jumpHeight = 100f;        private TimeSpan _jumpTimeSpan = TimeSpan.FromMilliseconds(500);        private double _jumpStartTime;        private float _jumpStartPosition;

Code in Update:

_jumpKeyDown = Keyboard.GetState().IsKeyDown(Keys.Space);            squarePosition.Y = DoJump(squarePosition.Y, gameTime);

High Algorithm functions:

        private float DoJump(float velocityY, GameTime gameTime)        {            if (_jumpKeyDown && !_isJumping)            {                _isJumping = true;                _jumpStartTime = gameTime.TotalGameTime.TotalMilliseconds;                _jumpStartPosition = velocityY;            }            if (_isJumping)            {                var jumpTime = gameTime.TotalGameTime.TotalMilliseconds - _jumpStartTime;                var topTime = _jumpTimeSpan.TotalMilliseconds / 2;                if (jumpTime < _jumpTimeSpan.TotalMilliseconds)                {                    if (jumpTime > topTime)                    {                        velocityY =                            _jumpStartPosition-_jumpHeight - Convert(-(jumpTime - topTime) * _jumpHeight / (_jumpTimeSpan.TotalMilliseconds - topTime));                    }                    else                    {                        velocityY =_jumpStartPosition+ Convert(-( jumpTime)*_jumpHeight/topTime);                    }                }                else                {                    _isJumping = false;                    velocityY = _jumpStartPosition;                }            }            return velocityY;        }