Simplify Arithmetic operations.

When including constants in arithmetic operations, compound the values together where possible. For example, instead of coding ;

offset = 224 + revstart + 1;

code

offset = 225 + revstart ;

This is especially time consuming for large datasets. If this makes the code less clear, add a comment to explain the use.

Where possible, use multiply rather than divide (e.g. Use X=X*0.5 rather than X=X/2), since multiplication is quicker.
Additionally, when dividing, if division by zero is a (frequent) possibility test for this before dividing. If the divisor used in division is zero, the operation becomes far slower. However, testing for a zero also uses CPU so some consideration of this is necessary.