在 C 中仅使用 8 位算术将 8 位数字从 0-255 缩放到 0-100 的简单方法？

Question

I have an 8-bit unsigned number from 0-255. I need to scale it to 0-100 without using anything other than 8-bit integer arithmetic, including casting, copying to other variables, etc. due to a micro controller limitation.

What is an accurate way for me to do this scaling?

Answer 1

You will need to use 16 bits for this.

Put the value in the high byte of a 16-bit register and:

x >> 2 + x >> 3 + x >> 6 + x >> 8

The result will be in the high byte of the register.

Implementation using only 8-bit registers is left as an exercise for the reader.