CSC231 Homework 2 Solutions 2014
--D. Thiebaut (talk) 13:41, 22 September 2014 (EDT)
Problem 1
;;; -----------------------------------------------------
;;; hw2_1.asm
;;; D. Thiebaut
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf hw2_1.asm
;;; ld -melf_i386 hw2_1.o 231Lib.o -o hw2_1
;;; ./hw2_1
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x dd 0 ; the integer used for IO
msgX db "x = "
z dd 0 ; the integer used for IO
msgZ db "z = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov dword[x], eax
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, dword[x]
call _printDec
call _println
mov eax, dword[x]
add eax, eax
add eax, eax
sub eax, 1
mov dword[z], eax
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, dword[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
Problem 2
;;; -----------------------------------------------------
;;; hw2_2.asm
;;; D. Thiebaut
;;; Simple skeleton program illustrating how to get an
;;; integer from the command line and displaying it back
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf hw2_2.asm
;;; ld -melf_i386 hw2_2.o 231Lib.o -o hw2_2
;;; ./hw2_2
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x dd 0 ; the integer used for IO
msgX db "x = "
z dd 0 ; the integer used for IO
msgZ db "z = "
y dd 0 ; the integer used for IO
msgY db "y = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov dword[x], eax
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov dword[y], eax
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, dword[x]
call _printDec
call _println
;;; print "y = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgY
mov edx, 4
call _printString
mov eax, dword[y]
call _printDec
call _println
;;; compute z = 2 * x - 3 * y + 7
mov eax, dword[x]
add eax, eax
sub eax, dword[y]
sub eax, dword[y]
sub eax, dword[y]
add eax, 7
mov dword[z], eax
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, dword[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
Problem 3
;;; -----------------------------------------------------
;;; hw2_3.asm
;;; D. Thiebaut
;;; Simple skeleton program illustrating how to get an
;;; integer from the command line and displaying it back
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf hw2_3.asm
;;; ld -melf_i386 hw2_3.o 231Lib.o -o hw2_3
;;; ./hw2_3
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x dd 0 ; the integer used for IO
msgX db "x = "
z dd 0 ; the integer used for IO
msgZ db "z = "
y dd 0 ; the integer used for IO
msgY db "y = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov dword[x], eax
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov dword[y], eax
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, dword[x]
call _printDec
call _println
;;; print "y = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgY
mov edx, 4
call _printString
mov eax, dword[y]
call _printDec
call _println
;;; compute z = ( x + y )* 3 + ( x - y ) * 4
mov eax, dword[x]
add eax, dword[y]
mov ebx, eax ; x + y
add ebx, eax ; 2*(x+y)
add ebx, eax ; 3*(x+y)
mov eax, dword[x]
sub eax, dword[y] ; (x-y)
add eax, eax ; 2*(x-y)
add eax, eax ; 4*(x-y)
sub ebx, eax ; 3(x+y) - 4(x-y)
mov dword[z], ebx
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, dword[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
Problem 4
;;; -----------------------------------------------------
;;; hw2_4.asm
;;; D. Thiebaut
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf hw2_4.asm
;;; ld -melf_i386 hw2_4.o 231Lib.o -o hw2_4
;;; ./hw2_4
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x dw 0 ; the integer used for IO
msgX db "x = "
z dw 0 ; the integer used for IO
msgZ db "z = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov word[x], ax
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, 0
mov ax, word[x]
call _printDec
call _println
mov eax, 0
mov ax, word[x]
add ax, ax
add ax, ax
sub ax, 1
mov word[z], ax
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, 0
mov ax, word[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
Problem 5
;;; -----------------------------------------------------
;;; Hw2_5.asm
;;; D. Thiebaut
;;; Simple skeleton program illustrating how to get an
;;; integer from the command line and displaying it back
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf Hw2_5.asm
;;; ld -melf_i386 Hw2_5.o 231Lib.o -o Hw2_5
;;; ./Hw2_5
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x dw 0 ; the integer used for IO
msgX db "x = "
z dw 0 ; the integer used for IO
msgZ db "z = "
y dw 0 ; the integer used for IO
msgY db "y = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov word[x], ax
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov word[y], ax
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, 0
mov ax, word[x]
call _printDec
call _println
;;; print "y = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgY
mov edx, 4
call _printString
mov eax, 0
mov ax, word[y]
call _printDec
call _println
;;; compute z = 2 * x - 3 * y + 7
mov ax, word[x]
add ax, ax
sub ax, word[y]
sub ax, word[y]
sub ax, word[y]
add ax, 7
mov word[z], ax
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, 0
mov ax, word[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
Problem 6
;;; -----------------------------------------------------
;;; Hw2_6.asm
;;; D. Thiebaut
;;; Simple skeleton program illustrating how to get an
;;; integer from the command line and displaying it back
;;;
;;; To assemble, link and run:
;;; nasm -f elf 231Lib.asm
;;; nasm -f elf Hw2_6.asm
;;; ld -melf_i386 Hw2_6.o 231Lib.o -o Hw2_6
;;; ./Hw2_6
;;; -----------------------------------------------------
;;; extern functions that will be linked to this program
;;; contained in 231Lib.asm
extern _printDec
extern _printString
extern _println
extern _getInput
;;; -----------------------------------------------------
;;; data section
;;; -----------------------------------------------------
section .data
x db 0 ; the integer used for IO
msgX db "x = "
z db 0 ; the integer used for IO
msgZ db "z = "
y db 0 ; the integer used for IO
msgY db "y = "
prompt db "> "
;;; -----------------------------------------------------
;;; code section
;;; -----------------------------------------------------
section .text
global _start
_start:
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov byte[x], al
;;; get number from user
mov ecx, prompt
mov edx, 2
call _printString
call _getInput
mov byte[y], al
;;; print "x = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgX
mov edx, 4
call _printString
mov eax, 0
mov al, byte[x]
call _printDec
call _println
;;; print "y = dddd" where dddd is the contents of x
;;; in decimal
mov ecx, msgY
mov edx, 4
call _printString
mov eax, 0
mov al, byte[y]
call _printDec
call _println
;;; compute z = ( x + y )* 3 + ( x - y ) * 4
mov al, byte[x]
add al, byte[y]
mov bl, al ; x + y
add bl, al ; 2*(x+y)
add bl, al ; 3*(x+y)
mov al, byte[x]
sub al, byte[y] ; (x-y)
add al, al ; 2*(x-y)
add al, al ; 4*(x-y)
sub bl, al ; 3(x+y) - 4(x-y)
mov byte[z], bl
mov ecx, msgZ
mov edx, 4
call _printString
mov eax, 0
mov al, byte[z]
call _printDec
call _println
;;; ; exit
mov ebx, 0
mov eax, 1
int 0x80
