Expert: Brian Sill - 11/2/2009

Question
Plz help me write a program in Assembly Language to find the maximum number and the minimum number from an array of ten positive numbers. Store the minimum number in AX and maximum number in DX.

[Hint: Use the conditional jumps]  

Answer
Lily,
 Delphi creates very fast native code, so creating this in assembly seems like overkill. If you were searching for the min and max in an array of 1,000, or 10,000 then perhaps you may be able to gain some speed from Assembly. Also, the Assembly code can be gleaned from similar Delphi code. For example:

procedure MinMax(Input: Array of LongInt; var Min, Max: LongInt);
var
 I: LongInt;
begin
 Min:=Input[Low(Input)];
 Max:=Min;
 for I:=Low(Input)+1 to High(Input) do
 begin
   if (Input[I]<Min) then Min:=Input[I];
   if (Input[I]>Max) then Max:=Input[I];
 end;
end;

Now if you create a program that uses this procedure, and set a breakpoint on the first line above, and then run it, and check the CPU window when it stops, you'll see the Assembly code that Delphi created, and then if you see somewhere that the speed could be improved, you can copy that code, and re-implement it in assembly.

Sincerely,
Brian

PS. You'll have to change the types to WORD in order to get the compiler to create numbers that will fit in the registers you've listed above.