CSC231 Homework 7 2014

--D. Thiebaut (talk) 10:33, 11 November 2014 (EST)

---

Page under construction

This assignment is due on 11/18/14, at 11:55 p.m.

Preparation

• You may want to do some reading about the NEG and NOT instructions

• http://home.myfairpoint.net/fbkotler/nasmdocc.html#section-A.4.189
• http://cs.smith.edu/~thiebaut/ArtOfAssembly/CH06/CH06-2.html#HEADING2-313

Problem #1

• Use the 231Lib.asm library as inspiration and write a function called printInt that prints a 32-bit 2-s complement number on the screen.
• Your function should work similarly to printDec, in that the number to print is passed through eax, and not through the stack!
• Your function should not modify any of the registers, including eax.
• Your function should be made global so that a test program can call it.
• Submit your function in a program called Hw7_1.asm.

Example Test Program

          section .text

          extern  printInt
_start:
          mov     eax, 0
          call    printInt         ; prints 0
  
          mov     eax, 0xff
          call    printInt         ; prints 255

          mov     eax, -1
          call    printInt         ; prints -1

          mov     eax, 0xffffffff
          call    printInt         ; prints -1
          
          mov     eax, 1
          mov     ebx, 0
          int     0x80

Problem #2

• Write a function called printInt16 that prints a 16-bit 2's complement number on the screen.
• Your function should work similarly to printInt, but the number it prints is the number passed in ax (not eax).
• Your function should not modify any of the registers, including ax or the upper part of eax.
• Your function should be made global so that a test program can call it.
• Submit your function to Moodle in a program called Hw7_2.asm.

Example Test Program

          section .text

          extern  printInt16
_start:
          mov     ax, 0
          call    printInt16         ; prints 0
  
          mov     ax, 0xff
          call    printInt16         ; prints 255

          mov     eax, 0x0000ffff
          call    printInt16         ; prints -1

          mov     eax, 0xffff0001
          call    printInt16         ; prints 1
          
          mov     eax, 1
          mov     ebx, 0
          int     0x80