Fast file reader needed for large files

Require a C routine (not C#) to accept a few parameters, access a large file and return the data to our app We are looking for very very fast performance so only confident C programmers should apply. **Spec:** We have files of at least 4 different formats, each format being a dotNet structure. The structures vary from having one or two int32 variables to much more complex structures with fixed length strings, boolean, int32 and Uint64 variables, some variables being arrays. The files contain many array elements of one of these structures. We require one C routine that will read all the array elements from a named file, irrespective of which structure it is. Our app will call the C routine by passing in a descriptor or example of the structure, and the name of the file to read, and we need the C routine to return the array of elements. Our target is for the C routine to returen a 10BM data file in less that 100 ms.