From 2ed641f710b8cbb5b18e8d76ce6cc9f6be799281 Mon Sep 17 00:00:00 2001
From: Georges Hatem <georges@hatem.ws>
Date: Sat, 27 Apr 2024 23:22:08 +0300
Subject: [PATCH 1/2] additional LEMIRE hash function

---
 entries/ghatem-fpc/src/OneBRCproj.lpi | 60 ++++++++++++++++++++++++++-
 entries/ghatem-fpc/src/onebrc.pas     |  6 ++-
 2 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/entries/ghatem-fpc/src/OneBRCproj.lpi b/entries/ghatem-fpc/src/OneBRCproj.lpi
index 853c254..c19cbcd 100644
--- a/entries/ghatem-fpc/src/OneBRCproj.lpi
+++ b/entries/ghatem-fpc/src/OneBRCproj.lpi
@@ -15,7 +15,7 @@
       <UseAppBundle Value="False"/>
       <ResourceType Value="res"/>
     </General>
-    <BuildModes Count="5">
+    <BuildModes Count="7">
       <Item1 Name="Default" Default="True"/>
       <Item2 Name="Debug">
         <CompilerOptions>
@@ -137,6 +137,64 @@
           </Other>
         </CompilerOptions>
       </Item5>
+      <Item6 Name="HashMod">
+        <CompilerOptions>
+          <Version Value="11"/>
+          <PathDelim Value="\"/>
+          <Target>
+            <Filename Value="..\..\..\bin\ghatem"/>
+          </Target>
+          <SearchPaths>
+            <IncludeFiles Value="$(ProjOutDir)"/>
+            <UnitOutputDirectory Value="..\..\..\bin\lib\$(TargetCPU)-$(TargetOS)"/>
+          </SearchPaths>
+          <CodeGeneration>
+            <SmartLinkUnit Value="True"/>
+            <Optimizations>
+              <OptimizationLevel Value="3"/>
+            </Optimizations>
+          </CodeGeneration>
+          <Linking>
+            <Debugging>
+              <GenerateDebugInfo Value="False"/>
+              <RunWithoutDebug Value="True"/>
+            </Debugging>
+            <LinkSmart Value="True"/>
+          </Linking>
+          <Other>
+            <CustomOptions Value="-dRELEASE -dHASHMOD"/>
+          </Other>
+        </CompilerOptions>
+      </Item6>
+      <Item7 Name="LEMIRE">
+        <CompilerOptions>
+          <Version Value="11"/>
+          <PathDelim Value="\"/>
+          <Target>
+            <Filename Value="..\..\..\bin\ghatem"/>
+          </Target>
+          <SearchPaths>
+            <IncludeFiles Value="$(ProjOutDir)"/>
+            <UnitOutputDirectory Value="..\..\..\bin\lib\$(TargetCPU)-$(TargetOS)"/>
+          </SearchPaths>
+          <CodeGeneration>
+            <SmartLinkUnit Value="True"/>
+            <Optimizations>
+              <OptimizationLevel Value="3"/>
+            </Optimizations>
+          </CodeGeneration>
+          <Linking>
+            <Debugging>
+              <GenerateDebugInfo Value="False"/>
+              <RunWithoutDebug Value="True"/>
+            </Debugging>
+            <LinkSmart Value="True"/>
+          </Linking>
+          <Other>
+            <CustomOptions Value="-dRELEASE -dLEMIRE"/>
+          </Other>
+        </CompilerOptions>
+      </Item7>
     </BuildModes>
     <PublishOptions>
       <Version Value="2"/>
diff --git a/entries/ghatem-fpc/src/onebrc.pas b/entries/ghatem-fpc/src/onebrc.pas
index 746c3db..d45e1b1 100644
--- a/entries/ghatem-fpc/src/onebrc.pas
+++ b/entries/ghatem-fpc/src/onebrc.pas
@@ -140,7 +140,11 @@ procedure TMyDictionary.InternalFind(const aKey: Cardinal; out aFound: Boolean;
   vDbl := aKey * cHashConst;
   vDbl := vDbl - Trunc (vDbl);
   vIdx := Trunc (vDbl * cDictSize);
-{$ELSE}
+{$ENDIF}
+{$IFDEF LEMIRE}
+  vIdx := aKey * cDictSize shr 32;
+{$ENDIF}
+{$IFDEF HASHMOD}
   vIdx := aKey mod cDictSize;
 {$ENDIF}
 

From c1857b3e9244a518dac25871cff0dc7bad788421 Mon Sep 17 00:00:00 2001
From: Georges Hatem <georges@hatem.ws>
Date: Sat, 27 Apr 2024 23:24:43 +0300
Subject: [PATCH 2/2] different configurations documentation

---
 entries/ghatem-fpc/README.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/entries/ghatem-fpc/README.md b/entries/ghatem-fpc/README.md
index 0cf1e53..02614d1 100644
--- a/entries/ghatem-fpc/README.md
+++ b/entries/ghatem-fpc/README.md
@@ -6,6 +6,11 @@
 
 ## Usage
  - -t flag to specify the thread-count (default reads the thread-count available on the CPU)
+
+currently there are 3 configurations that can be compiled / run:
+ - `HASHMOD`: uses modulus for hashing, least collisions
+ - `HASHMULT`: alternative hashing, more collisions, faster on my PC, but seemingly slower on test PCs
+ - `LEMIRE`: faster hash function calculation, most collisions it seems, yet the fastest on my PC
  
 ## Hardware + Environment
 host: