How to transform Matlab function to s-function

Hello, I did my .m program ( Interpreted matlab function) , but when I want to go to practice, I find myself obliged to use a s-function instead of Interpreted matlab function , but I have coded in matlab (.m) and I do not really know the s-function . There's there a means to go directly from a program in .m to s-function ?? THANK YOU VERY MUCH