CSC231 Exercises with conditional jumps

From dftwiki3
Revision as of 09:11, 27 October 2008 by Thiebaut (talk | contribs)
Jump to: navigation, search

Exercises on Conditional Jumps

Finding the minimum

Find the minimum of 3 signed int variables a, b, and c

Loop until overflow

Print fibonacci numbers coded as unsigned words until the result overflows. Don't print erroneous numbers!


Scanning an array

Find the largest element of a 1-dimensional array of signed double-words.

Same question, but with unsigned double words.


Characters and lower/upper case conversion

The program makeUpper.asm transforms all characters in a string to uppercase, but will also transform other characters that are not letters.

Modify the program so that it modifies only characters between 'a' and 'z' included.

Long/short jumps

Conditional jumps can jump only +127 bytes down, -128 bytes up in the code. How can we code something like this:

                 cmp     eax,10
                 jl      there
                 ...
                 ...
        there:   ...


when the instruction at Label there is 1000 bytes away from the jl conditional jump?

Print 2-dimensional arrays

Write the code necessary for printing an array of chars (maze) using for-loops depending on i and j indexes.

;;;  ------------------------------------------------------------
;;;  data areas
;;;  ------------------------------------------------------------

        section .data
maze    db "################################"     
maze2   db "            #  #           #    "     
        db "#########   #  #  #######  #   #"
        db "#           #  #        #      #"
        db "#########         ##############"
        db "#           ####               #"
        db "################################"
C       equ maze2-maze  ; num of columns
R       equ 7           ; num of rows

i        dd          0
j        dd          0