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GETTING INTO A ROUTINE

Setting Up an Integer Print Routine

by George Martin

Start ı Determining Whatıs Needed ı A Definition ı For Arguments Sake ı The Code ı Sources and PDF

FOR ARGUMENT'S SAKE

For the different types of arguments except floating point types, the math involved to accomplish the formatting is simple and straightforward. But, the floating point requirements of the printf routines require that the floating point math routines be linked into the code. Therefore, using the built-in formatted print routines will expand the code by pulling in floating point routines, even if you never specify a floating point variable or format.

On one recent project, the code expanded by 4 KB when I used sprintf. If you need floating point operations in your embedded project, then most of the overhead is already there. But if you donıt need floating point and want to use printf, then youıre stuck with this code expansion. The worst part is that itıs code youıll never use.

The solution? I came across a neat download from Mr. Rud Merriman. Itıs dated 1991 and first appeared in Embedded Systems Programming. The code is a reduced version of printf, one with all the floating point options removed. This code supports the l, d, x, s, and c format types along with some special characters like \n and \r. But, the great part is that you can see Merrimanıs approach to formatted printing and tailor these routines to your particular situation.

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