Difference between revisions of "CSC231 Homework 5 2015"

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* Write a program called '''hw5_3.asm''', and make sure it contains a function called _printHex() that will take the contents of eax  in hexadecimal.
 
* Write a program called '''hw5_3.asm''', and make sure it contains a function called _printHex() that will take the contents of eax  in hexadecimal.
 +
* <font color="magenta">Make sure your code is well documented and formatted nicely in columns</font>.
 
* Make your program use the 231Lib library.
 
* Make your program use the 231Lib library.
 
* The main function of your program should be the following:
 
* The main function of your program should be the following:
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* Submit your program in the HW 5 PB 3 section, on Moodle.
 
* Submit your program in the HW 5 PB 3 section, on Moodle.
 
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<br />
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<showafterdate after="20151107 23:59" before="20151231 00:00">
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=Solution for Problems 1 &amp; 2=
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<br />
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* See [[Media:CSC231_hw5_1_solution.pdf | Kaitlyn]]'s solution for Problem 1
 +
* See [[Media:CSC231_hw5_2_solution.pdf | Kaitlyn]]'s solution for Problem 2
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<br />
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=Solution _printHex Function=
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<br />
 +
::<source lang="asm">
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                section .data
 +
table          db      "0123456789ABCDEF"
 +
hexString      db      "xxxxxxxx"
 +
tempEax        dd      0
 +
       
 +
                section .text
 +
_printHex:
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                pushad                  ; save all registers
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                mov    [tempEax], eax  ; save eax, as we are going to need it
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                                        ; several times, for all its digits
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                mov    ecx, 8          ; get ready to loop 8 times
 +
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        ;; get char equivalent to lower nybble of eax
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for:            and    eax, 0xF        ; isolate lower nybble of eax
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                add    eax, table      ; and translate it into ascii hex char
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                mov    bl, byte[eax]  ; bl <- ascii
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        ;; make eax point to place where to put this digit in hexString
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                mov    eax, hexString  ; beginning of table
 +
                add    eax, ecx        ; add ecx to it, since ecx counts
 +
                dec    eax            ; but eax 1 too big, decrement it
 +
                mov    byte[eax], bl  ; store ascii char at right index in hexString
 +
 +
        ;; shift eax down by 4 bits by dividing it by 16
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                mov    ebx, 16        ; ready to shift down by 4 bits
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                mov    edx, 0
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                mov    eax, [tempEax]  ; get eax back
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                div    ebx            ; shift down by 4
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                mov    [tempEax], eax  ; save again
 +
 +
                loop    for            ; and repeat, 8 times!
 +
       
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        ;; print the pattern in hexString, which contains 8 chars
 +
 +
                mov    ecx, hexString  ;
 +
                mov    edx, 8
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                call    _printString
 +
 +
                popad
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                ret
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 +
</source>
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</showafterdate>
 
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Latest revision as of 22:07, 17 November 2015

--D. Thiebaut (talk) 15:31, 21 October 2015 (EDT)



This assignment is due on 11/04/15, at 11:55 p.m.


Problem #1


  • Ssh to aurora.smith.edu using your 231a-xx account.
  • Go into your account's public_html directory.
  • Create a file with emacs, and call it javascriptTest.html.
  • Store the following code into it:


<html>
   <body>
   
      <script type="text/javascript">
         <!--
            var a = 33;
            var b = 10;
            var c = "Test";
            var i = 0;
            var linebreak = "<br />";

            document.write("sum_i=0^100 = ");
            sum = 0;
            for ( i=0; i<=100; i++ ) {
                sum = sum + i;
            }
            document.write( sum );
            document.write(linebreak);
         //-->
      </script>
      
      Example of Javascript arithmetic.
      <br />

   </body>
</html>


  • Make the file readable:
chmod a+r javascriptTest.html


CSC231JavascriptTest.png


Question
When performing arithmetic, how does Javascript score in terms of speed of execution, compared to Java and Python, as illustrated in the page on Nasm, Java, Python that we discussed in class?


Submit your answers as a pdf file called hw5_1.pdf. Include supporting data in the file. Submit it as a pdf file in the HW 5 PB 1 section on Moodle.


Problem #2


This question is similar to Problem 1, but you have to measure the speed of java performing arithmetic with BigIntegers, as compared to performing arithmetic with ints.

Question
Is using BigIntegers slower, or faster than using ints, and how much faster or slower? Please include supporting evidence in your answer. Submit a pdf of your answer called hw5_2.pdf in the HW 5 PB 2 section on Moodle.


Problem #3


  • Write a program called hw5_3.asm, and make sure it contains a function called _printHex() that will take the contents of eax in hexadecimal.
  • Make sure your code is well documented and formatted nicely in columns.
  • Make your program use the 231Lib library.
  • The main function of your program should be the following:


_start:       mov     eax, 0x12345678
              call    _printHex
              call    _println

              mov     eax, 0xABCDEF00
              call    _printHex
              call    _println

              mov     eax, 0x1234ABCD
              call    _printHex
              call    _println

exit:         mov     eax, 1
              mov     ebx, 0
              int     0x80


  • Its output should be 
12345678
ABCDEF00
1234ABCD
  • Submit your program in the HW 5 PB 3 section, on Moodle.


<showafterdate after="20151107 23:59" before="20151231 00:00">

Solution for Problems 1 & 2



Solution _printHex Function


                section .data
table           db      "0123456789ABCDEF"
hexString       db      "xxxxxxxx"
tempEax         dd      0
        
                section .text
_printHex:
                pushad                  ; save all registers
                mov     [tempEax], eax  ; save eax, as we are going to need it
                                        ; several times, for all its digits 
                mov     ecx, 8          ; get ready to loop 8 times

        ;; get char equivalent to lower nybble of eax
for:            and     eax, 0xF        ; isolate lower nybble of eax
                add     eax, table      ; and translate it into ascii hex char
                mov     bl, byte[eax]   ; bl <- ascii

        ;; make eax point to place where to put this digit in hexString
                mov     eax, hexString  ; beginning of table
                add     eax, ecx        ; add ecx to it, since ecx counts
                dec     eax             ; but eax 1 too big, decrement it
                mov     byte[eax], bl   ; store ascii char at right index in hexString

        ;; shift eax down by 4 bits by dividing it by 16
                mov     ebx, 16         ; ready to shift down by 4 bits
                mov     edx, 0
                mov     eax, [tempEax]  ; get eax back
                div     ebx             ; shift down by 4
                mov     [tempEax], eax  ; save again

                loop    for             ; and repeat, 8 times!
        
        ;; print the pattern in hexString, which contains 8 chars

                mov     ecx, hexString  ; 
                mov     edx, 8
                call    _printString

                popad
                ret

</showafterdate>



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