From 2abbae77d707203f1ff1ddf03022c2146f35f185 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Wed, 29 May 2024 01:01:16 +0200
Subject: [PATCH] Library: draft memory rearrangements

not clear yet how to handle the classical "realloc" situation
---
 src/lib/several-builder.hpp | 60 ++++++++++++++++++++++++++++++++++---
 wiki/thinkPad.ichthyo.mm    | 30 +++++++++++++++++++
 2 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/src/lib/several-builder.hpp b/src/lib/several-builder.hpp
index 8634322f9..3b2401a8f 100644
--- a/src/lib/several-builder.hpp
+++ b/src/lib/several-builder.hpp
@@ -47,22 +47,27 @@
 #include "lib/iter-explorer.hpp"
 #include "lib/util.hpp"
 
+#include <cstring>
 #include <utility>
 #include <vector>
 
 
 
-
 namespace lib {
   using std::vector;
   using std::forward;
   using std::move;
+  using std::byte;
   
-  namespace {// Allocation managment policies
+  namespace {// Allocation management policies
     
     struct HeapOwn
       {
-        
+        void*
+        realloc (void* data, size_t oldSiz, size_t newSiz)
+          {
+            UNIMPLEMENTED ("adjust memory allocation"); ///////////////////////////OOO Problem Objekte verschieben
+          }
       };
   }
   
@@ -115,7 +120,54 @@ namespace lib {
       void
       adjustStorage (size_t cnt, size_t spread)
         {
-          UNIMPLEMENTED ("allocation");
+          if (cnt*spread > storageSiz_)
+            {// need more storage..
+              Col::data_ = static_cast<typename Col::Bucket> (POL::realloc (Col::data_, storageSiz_, cnt*spread));
+              storageSiz_ = cnt*spread;
+            }
+          ENSURE (Col::data_);
+          if (spread != Col::data_->spread)
+            adjustSpread (spread);
+
+          if (cnt*spread < storageSiz_)
+            {// attempt to shrink storage
+              Col::data_ = static_cast<typename Col::Bucket> (POL::realloc (Col::data_, storageSiz_, cnt*spread));
+              storageSiz_ = cnt*spread;
+            }
+        }
+      
+      /** move existing data to accommodate spread */
+      void
+      adjustSpread (size_t newSpread)
+        {
+          REQUIRE (Col::size_);
+          REQUIRE (Col::data_);
+          REQUIRE (newSpread * Col::size_ <= storageSiz_);
+          size_t oldSpread = Col::data_->spread;
+          if (newSpread > oldSpread)
+            // need to spread out
+            for (size_t i=Col::size_-1; 0<i; --i)
+              shiftStorage (i, oldSpread, newSpread);
+          else
+            // attempt to condense spread
+            for (size_t i=1; i<Col::size_; ++i)
+              shiftStorage (i, oldSpread, newSpread);
+          // data elements now spaced by new spread
+          Col::data_->spread = newSpread;
+        }
+      
+      void
+      shiftStorage (size_t idx, size_t oldSpread, size_t newSpread)
+        {
+          REQUIRE (idx);
+          REQUIRE (oldSpread);
+          REQUIRE (newSpread);
+          REQUIRE (Col::data_);
+          byte* oldPos = Col::data_->storage;
+          byte* newPos = oldPos;
+          oldPos += idx * oldSpread;
+          newPos += idx * newSpread;
+          std::memmove (newPos, oldPos, util::min (oldSpread,newSpread));
         }
       
       template<class IT>
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index 22589bb90..59ea1f6b8 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -81870,6 +81870,25 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <node CREATED="1716909012702" ID="ID_1876994172" MODIFIED="1716909016713" TEXT="const-correctness">
 <node CREATED="1716909019405" ID="ID_1406909807" MODIFIED="1716909042294" TEXT="ein const Several&lt;X&gt; ist ein Several&lt;const X&gt;"/>
 </node>
+<node BACKGROUND_COLOR="#f8f1cb" COLOR="#a50125" CREATED="1716936826666" ID="ID_1382882363" MODIFIED="1716936834769" TEXT="Problem: Objekte verschieben">
+<icon BUILTIN="messagebox_warning"/>
+<node CREATED="1716936845950" ID="ID_715653412" MODIFIED="1716936862044" TEXT="eigentlich darf man das nur bei trivial kopierbaren Objekten">
+<node CREATED="1716936929564" ID="ID_707314614" LINK="https://en.cppreference.com/w/cpp/named_req/TriviallyCopyable" MODIFIED="1716936935390" TEXT="TriviallyCopyable"/>
+<node CREATED="1716937009097" ID="ID_284902115" MODIFIED="1716937022112" TEXT="au&#xdf;erdem: es darf keine Verzeigerung geben">
+<icon BUILTIN="stop-sign"/>
+</node>
+</node>
+<node CREATED="1716937025743" ID="ID_323500560" MODIFIED="1716937028858" TEXT="zwei F&#xe4;lle">
+<node CREATED="1716937029830" ID="ID_12032052" MODIFIED="1716937071076" TEXT="Spread ge&#xe4;ndert &#x27f6; in-place"/>
+<node CREATED="1716937071856" ID="ID_783851911" MODIFIED="1716937099960" TEXT="klassische re-Allokation an eine andere Stelle">
+<node CREATED="1716937118530" ID="ID_40686362" MODIFIED="1716937137107" TEXT="hier k&#xf6;nnte man alternativ auch die Objekte move-kopieren"/>
+<node CREATED="1716937138104" ID="ID_1463751078" MODIFIED="1716937157438" TEXT="aber: std::realloc gibt den alten Puffer sofort frei"/>
+</node>
+</node>
+<node BACKGROUND_COLOR="#f0d5c5" COLOR="#990033" CREATED="1716937163164" ID="ID_1513844512" MODIFIED="1716937171050" TEXT="wie geht std::vector damit um?">
+<icon BUILTIN="help"/>
+</node>
+</node>
 <node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1716914864769" ID="ID_966642586" MODIFIED="1716914906125" TEXT="Builder-Operationen">
 <icon BUILTIN="pencil"/>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1716914869721" ID="ID_756769385" MODIFIED="1716914902541" TEXT="basis-Allokation">
@@ -81880,10 +81899,21 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1716914886169" ID="ID_505410227" MODIFIED="1716914902542" TEXT="&#xc4;nderung Spread">
 <icon BUILTIN="flag-yellow"/>
+<node CREATED="1716936092764" ID="ID_618217173" MODIFIED="1716936100479" TEXT="Objekte einzeln verschieben"/>
+<node CREATED="1716936101233" ID="ID_1155209653" MODIFIED="1716936109052" TEXT="per std::memmove"/>
 </node>
 <node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1716914892972" ID="ID_1080699305" MODIFIED="1716914902543" TEXT="Platzieren neuer Daten">
 <icon BUILTIN="flag-yellow"/>
 </node>
+<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1716936138265" ID="ID_344813639" MODIFIED="1716936143886" TEXT="Allokations-Policies">
+<icon BUILTIN="flag-yellow"/>
+<node CREATED="1716936150419" ID="ID_442325434" MODIFIED="1716936174356" TEXT="HeapOwn">
+<node CREATED="1716936175678" ID="ID_1766388404" MODIFIED="1716936183114" TEXT="die C-Funktionen nutzen (wegen realloc)"/>
+<node CREATED="1716936231944" ID="ID_1000807546" LINK="https://en.cppreference.com/w/cpp/memory/c/realloc" MODIFIED="1716936247901" TEXT="Doku std::realloc()">
+<icon BUILTIN="info"/>
+</node>
+</node>
+</node>
 </node>
 </node>
 </node>