Difference between revisions of "CSC231 Homework 2 Solutions 2014"
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=Problem 4= | =Problem 4= | ||
<source lang="asm"> | <source lang="asm"> | ||
| + | ;;; ----------------------------------------------------- | ||
| + | ;;; 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 | ||
</source> | </source> | ||
=Problem 5= | =Problem 5= | ||
