Sheng Jiang 蒋晟

;=====================================================================

; Assignment1.asm – Homework Assignment 1

;

; Author: Sheng_Jiang

; Course: COSC 2425

; Date: 06/08/05

;=====================================================================

.386

.MODEL flat, stdcall

option casemap:none

include windows.inc

include kernel32.inc

include masm32.inc

includelib kernel32.lib

includelib masm32.lib

.DATA

;Playing with flags

FlagTest BYTE 0

SFlagTest SBYTE 0

;Summing up a series of unsigned numbers

DWORDArray DWORD 1,2,3,4,5,6,7,8,9,10

;Sum up all the positive and negative values

SDWORDArray SDWORD 1,-2,3,-4,5,-6,7,-8,9,-10

.CODE

main PROC

int 3

;Data for Playing with flags

mov FlagTest,1;

add FlagTest,255 ;set Carry flag ,FlagTest=0

add FlagTest,1 ;clear Carry flag ,FlagTest=1

sub FlagTest,1 ;set Zero flag ,FlagTest=0

add FlagTest,1 ;clear Zero flag ,FlagTest=1

sub SFlagTest,2 ;set Sign flag ,SFlagTest=-2

add SFlagTest,10 ;clear Sign flag ,SFlagTest=8

add SFlagTest,127 ;set Overflow flag ,SFlagTest=135

mov SFlagTest,0;

sub SFlagTest,100 ;clear Overflow flag,SFlagTest=-100

;Summing up a series of unsigned numbers

mov edi, OFFSET DWORDArray ;Begin

mov ecx, OFFSET DWORDArray+SIZEOF DWORDArray ;End

mov eax, 0 ;Initialize Sum

Sum1 :

add eax, [edi] ;sum

add edi, TYPE(DWORDArray) ;step to next

cmp ecx, edi ;loop test

jne Sum1 ;loop

; eax should be 55(37h) now

;Sum up all the positive and negative values

mov edi, OFFSET SDWORDArray ;Begin

mov ecx, OFFSET SDWORDArray+SIZEOF SDWORDArray;End

mov eax, 0 ;Initialize Sum

mov ebx, 0 ;Initialize Sum

Sum2 :

mov edx, [edi] ;compare edi with 0

cmp edx, 0

jl Sum2Neg ;jump to Sum2Neg, add to ebx if edi is a negative number

add eax, [edi] ;otherwise, add to eax

jmp Sum2Pos ;done, jump to loop point Sum2Pos

Sum2Neg:

add ebx, [edi] ;add to ebx if edi is a negative number

Sum2Pos:

add edi, TYPE(DWORDArray) ;step to next

cmp ecx, edi ;loop test

jne Sum2 ;loop

; eax should be 25(19h) now

; ebx should be -30(ffffffe2h) now

invoke ExitProcess, 0

main ENDP

END main