Difference between revisions of "CSC231 Homework 9 Solution"

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(New page: --~~~~ ---- __TOC__ =Assembly= The solution program is shown below. Check further down for details on how I created score files and checked their contents. <code><pre> ;;; ; hw9.asm ;;; ...)
 
 
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--[[User:Thiebaut|D. Thiebaut]] 19:53, 4 December 2008 (UTC)
 
--[[User:Thiebaut|D. Thiebaut]] 19:53, 4 December 2008 (UTC)
 
----
 
----
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<onlydft>
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__TOC__
 
__TOC__
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This is the solution page for [[CSC231 Homework 9| Homework #9]].
 +
 
=Assembly=
 
=Assembly=
 
The solution program is shown below.  Check further down for details on how I created score files and checked their contents.
 
The solution program is shown below.  Check further down for details on how I created score files and checked their contents.
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=Creating Score Files=
 
=Creating Score Files=
  
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To create a score file I simply used an assembly file in which I store the score in memory and write the contents of the memory buffer to a file.
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To create different score files to test the programs, I simply used an already written assembly program that stored a portion of memory to file, and in which I put the score array in memory, a the beginning address associated with the label 'buffer'.  Then it's only a question of writing the contents of the memory buffer to the score file.
  
 
<code><pre>
 
<code><pre>
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noRead  dd    0              ; to store # of chars read from file
 
noRead  dd    0              ; to store # of chars read from file
  
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;;; some variables of interest
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;;; ============= THE SCORES!!! ===============
  
 
buffer  equ    $
 
buffer  equ    $
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         db      'ABC'
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         db      'ABC'                 ; User ABC has Score 10
 
         dd      10
 
         dd      10
 
         db      '233'
 
         db      '233'
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mov ebx,0
 
mov ebx,0
 
int 0x80 ; final system call
 
int 0x80 ; final system call
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−
 
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;;; ---------------------------------------------------------
 
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;;; sleep: assuming a 2 GHz processor, the instruction
 
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;;;        for: loop for  should take 1 cycle to execute
 
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;;;        since the processor goes through 2E09 cycles
 
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;;;        per second, loading ecx with 2000000000 before
 
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;;;        the loop should yield something in the order of
 
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;;;        a second delay.
 
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sleep:  push    ecx
 
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        mov    ecx, 2000000000
 
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.for    loop    .for
 
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        pop    ecx
 
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        ret
 
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=Dumping the contents of a score file=
 
=Dumping the contents of a score file=
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This [[CSC231 dumpScore.py |python program]] was used to display the contents of the score file on the screen.
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 +
<code><pre>
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#! /usr/bin/python
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# dumpScores.py
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# D. Thiebaut
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# read binary file of scores where a score is represented by
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# 3 ascii chars followed by a 4-byte integer in little-endian
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# format.
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# Syntax: dumpScore.py score_file_name  message
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#
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import struct
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import sys
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def displayScoreFile( fileName="scores.dat", message="" ):
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    """ reads the score file, unpacks it, and displays it """
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    fmt = 'ccci'  # format of the binary records
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    record_size = struct.calcsize( fmt ) # size of record
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    if len( message ):
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        print "-------------------------------------"
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        print " "* (len( message)/2),message
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        print "-------------------------------------"
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    smallestInitials="???"        # id of smallest score
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    smallest        = 99999999    # to be sure we catch the smallest
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    largestInitials = "???"        # id of largest score
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    largest        = -1          # to catch the largest
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 +
    try:
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        file = open( fileName, "rb" )  # open file
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    except:
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        print "could not open file"
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        return
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 +
    while True:                    # keep reading until the eof
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        block = file.read( 3 )    # read 3 bytes
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        if len( block )==0:        # can't? then break
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            break
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        (i1,i2,i3 ) = struct.unpack( 'ccc', block )
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        block = file.read( 4 )    # unpack as 3 chars, read 4 bytes
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        if block is None:          # can't? then break
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            break
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        score = struct.unpack( 'i', block )[0]
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                                  # unpack as a 32-bit int
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        if ( score > largest ):    # find largest...
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            largest = score
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            largestInitials = i1+i2+i3
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        if ( score < smallest ):  # and smallest...
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            smallest = score
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            smallestInitials = i1+i2+i3
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        print i1+i2+i3, score
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 +
    print "-------------------------------------"
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    print "Smallest score: %s %d" % (smallestInitials, smallest)
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    print "Largest score:  %s %d" % (largestInitials, largest)
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    print "-------------------------------------"
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#--------------------------------------------------------------
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# main program: gets the arguments, which should be the
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# name of the score file followed by a message to be printed
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# in the header of the display.
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#--------------------------------------------------------------
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argv = sys.argv
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if len( argv ) == 1:
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    file = raw_input( "score file? " )
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else:
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    file = argv[1]
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if len( argv ) > 2:
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    msg = ' '.join( argv[2:] )
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else:
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    msg = file
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displayScoreFile( file, msg )
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 +
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</pre></code>
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</onlydft>
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[[Category:CSC231]]

Latest revision as of 19:34, 14 September 2010

--D. Thiebaut 19:53, 4 December 2008 (UTC)


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