Tutorial: Moodle VPL -- Test Function of Student Program Multiple Times

--D. Thiebaut (talk) 22:44, 21 October 2014 (EDT)

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Moodle VPL Tutorials

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This VPL activity tests an assembly program that contains a function (_printHex) that is declared global. The module invalidates the _global label of the student program, links it with a test program (test.asm) which calls _printHex several times with different parameter values. The vpl_validate.sh script checks the correct output of the function.

Vpl_run.sh

#! /bin/bash
   
cat > vpl_execution <<EOF
#! /bin/bash
prog=Hw4_4

# replace the _start label in the student program
# so that the test program will start.
sed -i 's/_start/start/g' \$prog.asm


nasm -f elf test.asm
nasm -f elf  \$prog.asm
ld -melf_i386 -o \$prog \$prog.o test.o
./\$prog | cat -v
EOF
  
chmod +x vpl_execution

vpl_evaluate.sh

#! /bin/bash
   
cat > vpl_execution <<EOF
#! /bin/bash
prog=Hw4_4

# replace the _start label in the student program
# so that the test program will start.
sed -i 's/_start/start/g' \$prog.asm


nasm -f elf test.asm
nasm -f elf  \$prog.asm
ld -melf_i386 -o \$prog \$prog.o test.o

./\$prog | cat -v | grep -i ERROR &> grepLines.out

if [ -s grepLines.out ] ; then 
    echo "Comment :=>> _printHex modifies some of the registers"
    echo "Grade :=>> 40"
    exit
fi

for pattern in 12345678 ABCDEF00 ; do 
   ./\$prog | cat -v | grep -i \$pattern  &> grepLines.out
   if [ ! -s grepLines.out ] ; then 
      echo "Comment :=>> _printHex does not correctly prints \$pattern"
      echo "Grade :=>> 40"
      exit
   fi
done

echo "Comment :=>> Congrats, your _printHex passes the tests."
echo "Grade :=>> 100"


EOF

chmod +x vpl_execution

test.asm

;;; test.asm
;;; D. Thiebaut
extern          _printHex

;;;  ------------------------------------------------------------
;;;  data areas
;;;  ------------------------------------------------------------
                section .data
linefeed        db      10
msg             db      10,"ERROR:",10
                db      "Your _printHex function modifies some of the registers"
                db      10,10,10
MSGLEN          equ     $-msg
        
                section .text
                global  _start

setRegs:        mov     ebx, 0x1234567A
                mov     edx, 0xaaaa5555
                mov     ecx, 0xffff0000
                mov     esi, 0xaaaabbbb
                mov     edi, 0xeeeeffff
                ret

testRegs:       cmp     ebx, 0x1234567A
                jne     bad
                cmp     edx, 0xaaaa5555
                jne     bad
                cmp     ecx, 0xffff0000
                jne     bad
                cmp     esi, 0xaaaabbbb
                jne     bad
                cmp     edi, 0xeeeeffff
                jne     bad
                ret
bad:            mov     eax, 4
                mov     ebx, 1
                mov     ecx, msg
                mov     edx, MSGLEN
                int     0x80
                jmp     exit
        
printLn:        pushad
                mov     ecx, linefeed
                mov     edx, 1
                mov     eax, 4
                mov     ebx, 1
                int     0x80
                popad
                ret
_start:
                mov     eax, 0

                call    setRegs
                call    _printHex
                call    testRegs
                call    printLn

                mov     eax, 0x12345678
                call    _printHex
                call    printLn

                mov     eax, 0xABCDEF00
                call    _printHex
                call    printLn
                
;;;  exit()
exit:   
                mov     eax,1
                mov     ebx,0
                int     0x80    ; final system call

Solution Program: Hw4_4.asm

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