Извлечение битовой маски из integer

function ExtractBits(const Value, Start, Count: Integer): Integer;

const

Mask: array[0..31] of Integer =

($01,$03,$07,$0F,$1F,$3F,$7F,$FF,

$01FF,$03FF,$07FF,$0FFF,$1FFF,$3FFF,$7FFF,$FFFF,

$01FFFF,$03FFFF,$07FFFF,$0FFFFF,

$1FFFFF,$3FFFFF,$7FFFFF,$FFFFFF,

$01FFFFFF,$03FFFFFF,$07FFFFFF,$0FFFFFFF,

$1FFFFFFF,$3FFFFFFF,$7FFFFFFF,$FFFFFFFF);

asm

xchg ECX,EDX

test EDX,EDX

jnz @@isoke

xor EAX,EAX

jmp @@ending

@@isoke:

dec EDX

and EDX,31

shr EAX,cl

and EAX,dword ptr [Mask+EDX*4]

@@ending:

end;