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rtl-generics: speed up quadratic probe function. If the hash table size is a prime number and load factor is < 0.5 then the probe function p(k,i)=(h(k)+sqr(i)) is sufficient.

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git-svn-id: trunk@35627 -
This commit is contained in:
maciej-izak 2017-03-19 16:00:11 +00:00
parent 2357ca1fe6
commit dcf172dee4
1 changed files with 1 additions and 12 deletions
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13
packages/rtl-generics/src/generics.memoryexpanders.pas
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@ -47,12 +47,7 @@ type
{ TQuadraticProbing } { TQuadraticProbing }
TQuadraticProbing = class(TProbeSequence) TQuadraticProbing = class(TProbeSequence)
private
class constructor Create;
public public
class var C1: UInt32;
class var C2: UInt32;
class function Probe(I, Hash: UInt32): UInt32; static; inline; class function Probe(I, Hash: UInt32): UInt32; static; inline;
const MAX_LOAD_FACTOR = 0.5; const MAX_LOAD_FACTOR = 0.5;
@ -214,15 +209,9 @@ end;
{ TQuadraticProbing } { TQuadraticProbing }
class constructor TQuadraticProbing.Create;
begin
C1 := 1;
C2 := 1;
end;
class function TQuadraticProbing.Probe(I, Hash: UInt32): UInt32; class function TQuadraticProbing.Probe(I, Hash: UInt32): UInt32;
begin begin
Result := (Hash + C1 * I {%H-}+ C2 * Sqr(I)); Result := (Hash + Sqr(I));
end; end;
{ TDoubleHashingNoMod } { TDoubleHashingNoMod }