I'm having trouble figuring out how to compare inputs to negatives in MASM. Usually for positive input integers, I would just use cmp but that doesn't seem to be working for me in this program.
I'm also missing one or two lines in my calcLoop I think, because the program just ends right after the user inputs the positive value, after inputting all the negative values. This program should just add up and average all the values entered, all but one should be negatives between [-100,-1]. Also when I input -100 or -1, these should be allowed but are not.
Any help would be greatly appreciated as I'm still trying to figure out some of the basics of Assembly. Thanks!
Code:
TITLE Program3 (program3.asm)
INCLUDE Irvine32.inc
LENGTHLIMIT = 20
.data
intro BYTE "Program 3: Accumulator by ", 13,10
BYTE "What is your name: ",0
prompt1 BYTE "Oh hello, ",0
enterNumPrompt BYTE "Enter numbers between -100 and -1.",13,10
BYTE "Enter a non-negative now: ",13,10,0
prompt2 BYTE "Enter #: ",0
prompt3 BYTE "Okay, ",0
prompt4 BYTE " numbers.",0
addPrompt BYTE "The sum of the numbers entered is, ",0
roundPrompt BYTE "The rounded average is: "
errorPrompt BYTE "Whoops! Only numbers less than or equal to -1, please",13,10,0
nameInputLimit BYTE 24 DUP(0)
seeya BYTE "Thanks for using the accumulator, "
seeyaName BYTE "!"
numEntered DWORD ?
amountOfNums DWORD ?
result DWORD ?
sumResult DWORD ?
avgResult DWORD ?
.code
main PROC
mov edx, OFFSET intro
call Crlf
call WriteString
mov edx, OFFSET nameInputLimit
mov ecx, SIZEOF nameInputLimit
call ReadString
mov edx, OFFSET prompt1
call WriteString
mov edx, OFFSET nameInputLimit
call WriteString
call Crlf
mov edx, 0000000h
mov edx, OFFSET enterNumPrompt
call WriteString
call Crlf
call Crlf
getLoop:
mov edx, OFFSET prompt2
call WriteString
call ReadInt
cmp eax, -100
jg errorLoop
cmp eax, -1
jl complete
jmp calcLoop
errorLoop:
mov edx, OFFSET errorPrompt
call WriteString
jmp getLoop
calcLoop: ;missing a line or two here I think
mov numEntered, eax
mov eax, result
add eax, numEntered
mov result, eax
jmp getLoop
complete:
call Crlf
mov numEntered, eax
goodbye:
mov edx, OFFSET seeya
call WriteString
exit
; (insert executable instructions here)
exit
main ENDP
; (insert additional procedures here)
END main
Your instructions are correctly chosen, but the program flow needed some fixing.
Just for clarity, these are the relevant comparison instructions.
JG - Greather than? (signed numbers e.g. -128 to 127)
JL - Less than? (signed numbers e.g. -128 to 127)
JA - Above? (unsigned numbers e.g. 0 to 255)
JB - Below? (unsigned numbers e.g. 0 to 255)
Below is a fixed version of your main loop:
...
getLoop:
mov edx, OFFSET prompt2
call WriteString
call ReadInt
; !!!TODO!!! Add an abort condition jumping to 'complete' here!
cmp eax, -100
jl errorloop ; was 'jg errorLoop' - better goto error if less than -100
cmp eax, -1
jg errorloop ; was 'jl complete' - now error on value greater than -1
add result, eax ; more is not necessary
jmp getLoop
errorLoop:
mov edx, OFFSET errorPrompt
call WriteString
jmp getLoop