Modifying strings in emu8086 assembly

Question

I currently working on an intro assignment for a computer architecture course and i was asked to accomplish some string modifications. My question is not how to do it, but what should i be researching to be able to do it? Is there any functions that will make this easier, for example .reverse() is java.

What i need to accomplish is getting string input from the user, reverse the letters (while reversing numbers keep them where they are), add spaces whenever there is a vowel, and alternate the caps.

Example:

 Input: AbC_DeF12 
 Output: f E d _ c B a 2 1

This is code i ripped from the lecture: http://pastebin.com/2E1UtGdD I put it in pastebin to avoid clutter. Anything used in this is fair game. (this code does have limitiations though, it only support ~9 characters and the looping doesn't work at the end of strings)

Answer 1

I would look at it like this.

Generate a function on paper of how you want to achieve this. This is notes and only a starting point.

Loop from 0 to string length.
if(byte >= 'A' || byte <= 'Z') then byte -= 'A' - 'a'; /* convert to lower case */
if(byte >= 'a' || byte <= 'z') then byte += 'A' - 'a'; /* convert to upper case */

/* Switch the letters only. */
a = 0; b = string length

Loop i from a to b. if((input >= 'A' && input <='Z') || (input >= 'a' && input <='z')) p = i
Loop j from b to a. if((input >= 'A' && input <='Z') || (input >= 'a' && input <='z')) q = j

c = input[i]; input[i] = input[j]; input[j] = c;

/* Regenerate the string and add spaces. */
loop i, 0 to string length
if(input[i] == 'A' 'a' 'E' 'e' ...) string2[j] = ' '; j++; string2[j] = input[i]; j++;
i++

After that if you don't know 8086 I would look at examples online of how to do each individual part. The most important bit is generating the code in your head and on paper on how it is going to work.