CODEWITHSUNDEEP
delphi
user1593881
user1593881

Reputation:

Combine two bytes in delphi

Provided that I have two bytes variables in Delphi:

var 
    b1,b2,result:byte;
begin
    b1:=$05;
    b2:=$04;
    result:=??? // $54
end;

How would I then combine the two to produce a byte of value $54?

Upvotes: 1

Views: 892

Answers (2)

Johan
Johan

Reputation: 76753

The best way would be to:

interface

function combine(a,b: integer): integer; inline;  //allows inlining in other units

implementation

function combine(a,b: cardinal): cardinal; inline;
begin
  Assert((a <= $f));
  Assert((b <= $f));
  Result:= a * 16 + b;
end;

Working with byte registers slows down the processor due to partial register stalls.
The asserts will get eliminated in release mode.

If performance matters never use anything but integers (or cardinals).

I have no idea why people are talking about VMT's or dll's. It's a simple inline method that does not even generate a call.

Upvotes: 1

Andrea Korinski
Andrea Korinski

Reputation: 275

The most trivial way is

result := b1 * $10 + b2

"Advanced" way:

result := b1 shl 4 + b2

Upvotes: 3

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