The author discussed dealing with integer values encoded in predefined bit widths and signed-ness in a bit-packed format, with a focus on sign-extending narrow types. They highlighted a method to sign-extend that doesn’t involve bit-shifting at all. This method makes it easier to handle a mixture of bit widths and support both signed and unsigned values with the same code. The author revealed a cleaner formulation suggested by Harold Aptroot for the sign-extend function, simplifying the process. Overall, the approach presented is a neat solution that eliminates the need for explicit tests for signed or unsigned values, making it a practical and efficient coding technique.
https://fgiesen.wordpress.com/2024/10/23/zero-or-sign-extend/