How to write an assembly sorting program 8086 with works with 6 digits numbers?

im new to assembly language and i know many codes. However im working with 8086 emulator with only works with 16 bit numbers. this is a home work that im really stuck in : How can i write an assembly code with do the following :

1-get 20 , maximum 6-digits decimal numbers and store them in an array.

2- sort the array in ascending order.

its really hard for me to understand how to manage registers and stack for this long numbers.

every help will be appreciated in advance .

Answers


In order to sort 32bit numbers (or broader) with 16bit registers you have to compare the upper part of each number separately.

Assume we have these random two 32 bit numbers (shown in hex) 4567afdf and 321abc09.

Now when you look at them as 16 bit values they look like this:

4567 afdf
321a bc09

As you can easily see, the upper 16 bits you can compare individually.

If the upper 16 bits are higher or lower, then you know that the lower part doesn't matter anymore and you sort them accordingly.

If the upper 16 bits are equal, then you compare the lower 16 bits and if they are also equal, both numbers are equal => no sort needed, otherwise you shuffle them accordingly. Since the upper 16 bits are also equal, you don't even need to shuffle them.

If the upper 16bits are different, you still have to shuffle the lower 16 bits accordingly, as they might be different.

The basics of this approach can be used for an arbitrary number of bits not just 32bits. Generally when you have a seemingly hard problem, you should try to think of the easy examples and how you can solve it. Then you can extend it to more complicated cases.

EDIT:

An alternative approach would be, if you have strings of decimal numbers and you want to sort them based on the string representation instead of the numbers.

In this case, you can do it as follows

  1. If the length of the two number strings are differnt, the shorter one is the lower number.
  2. if the length is equal, then you can look at each digit individually (starting with the first digit) until you hit a non-equal digit or the string end. If you reaced the end of the string, the numbers are the same, otherwise you kn ow which one is higher/lower.

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