I'm trying to write a simple program in Easy68k that stores to negative values, adds them together, and then outputs them in the console. I am having trouble figuring out how to represent the negative numbers. We are asked that they be in hex format and output in decimal. Everything seems correct but the values themselves. I used 2s complement and then converted the two numbers to hex.
First decimal number = -102 Second decimal number = -87
Using 2s complement I converted the two numbers to hex (though I'm not sure if this is even correct): -102 -> 1A -87 -> 29
Here's my code so far:
addr EQU $7CE0
data1 EQU $1A
data2 EQU $29
ORG $1000
START: ; first instruction of program
* Put program code here
MOVE #data2,D1
MOVEA.W #addr,A0
ADD #data1,D1
MOVE D1,(A0)
MOVE.B #3,D0
TRAP #15
* Variables and Strings
* Put variables and constants here
END START ; last line of source
I even tried to just convert binary versions of the negative numbers straight to hex:
-102 -> 11100110 -> E6
-87 -> 11010111 -> D7
Which didn't work either. I also tried storing the binary version and adding them, but got the same result.
Here's the question:
Write a program in assembly to add the two numbers (-102 and -87). Inputs should be in hexadecimal format. Store the result in hexadecimal at an address $7CE0. Print out the result in decimal.(Hint: use the track function task #3). If an error happens, you should also print out the error message as well.
I know I am misrepresenting the two negative numbers, but I just can't figure out how to do it right. I've looked everywhere and found nothing on how to store/add/output negative numbers in 68k. Any help is appreciated, this is for an assignment so I'm not expecting direct answers. Thanks!
