发送位置期望值至飞控（输入：期望xyz,期望yaw）

take a -128..127 value and stbi__clamp it and convert to 0..255

returns 1 if "a*b*c + add" has no negative terms/factors and doesn't overflow

SEE https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf FOR DETAILS

旋转矩阵：机体系到惯性系

【打印参数函数】

From http://en.wikipedia.org/wiki/Box%E2%80%93Muller_transform

initialize a callback-based context

initialize a memory-decode context

* Setter functions MUST be used carefully - If you arbitrarily change SDF values, it is not a proper SDF any more! * * Use of these function

Detect object in the current frame.

Set errno variable */

if there's a pending marker from the entropy stream, return that otherwise, fetch from the stream and get a marker. if there's no marker, return 0xff,

returns 1 if the product is valid, 0 on overflow. negative factors are considered invalid.